xref: /openbmc/linux/drivers/acpi/acpi_video.c (revision 2f164822)
1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  *  video.c - ACPI Video Driver
4  *
5  *  Copyright (C) 2004 Luming Yu <luming.yu@intel.com>
6  *  Copyright (C) 2004 Bruno Ducrot <ducrot@poupinou.org>
7  *  Copyright (C) 2006 Thomas Tuttle <linux-kernel@ttuttle.net>
8  */
9 
10 #define pr_fmt(fmt) "ACPI: video: " fmt
11 
12 #include <linux/kernel.h>
13 #include <linux/module.h>
14 #include <linux/init.h>
15 #include <linux/types.h>
16 #include <linux/list.h>
17 #include <linux/mutex.h>
18 #include <linux/input.h>
19 #include <linux/backlight.h>
20 #include <linux/thermal.h>
21 #include <linux/sort.h>
22 #include <linux/pci.h>
23 #include <linux/pci_ids.h>
24 #include <linux/slab.h>
25 #include <linux/dmi.h>
26 #include <linux/suspend.h>
27 #include <linux/acpi.h>
28 #include <acpi/video.h>
29 #include <linux/uaccess.h>
30 
31 #define ACPI_VIDEO_BUS_NAME		"Video Bus"
32 #define ACPI_VIDEO_DEVICE_NAME		"Video Device"
33 
34 #define MAX_NAME_LEN	20
35 
36 MODULE_AUTHOR("Bruno Ducrot");
37 MODULE_DESCRIPTION("ACPI Video Driver");
38 MODULE_LICENSE("GPL");
39 
40 static bool brightness_switch_enabled = true;
41 module_param(brightness_switch_enabled, bool, 0644);
42 
43 /*
44  * By default, we don't allow duplicate ACPI video bus devices
45  * under the same VGA controller
46  */
47 static bool allow_duplicates;
48 module_param(allow_duplicates, bool, 0644);
49 
50 #define REPORT_OUTPUT_KEY_EVENTS		0x01
51 #define REPORT_BRIGHTNESS_KEY_EVENTS		0x02
52 static int report_key_events = -1;
53 module_param(report_key_events, int, 0644);
54 MODULE_PARM_DESC(report_key_events,
55 	"0: none, 1: output changes, 2: brightness changes, 3: all");
56 
57 static int hw_changes_brightness = -1;
58 module_param(hw_changes_brightness, int, 0644);
59 MODULE_PARM_DESC(hw_changes_brightness,
60 	"Set this to 1 on buggy hw which changes the brightness itself when "
61 	"a hotkey is pressed: -1: auto, 0: normal 1: hw-changes-brightness");
62 
63 /*
64  * Whether the struct acpi_video_device_attrib::device_id_scheme bit should be
65  * assumed even if not actually set.
66  */
67 static bool device_id_scheme = false;
68 module_param(device_id_scheme, bool, 0444);
69 
70 static int only_lcd = -1;
71 module_param(only_lcd, int, 0444);
72 
73 static int register_backlight_delay;
74 module_param(register_backlight_delay, int, 0444);
75 MODULE_PARM_DESC(register_backlight_delay,
76 	"Delay in seconds before doing fallback (non GPU driver triggered) "
77 	"backlight registration, set to 0 to disable.");
78 
79 static bool may_report_brightness_keys;
80 static int register_count;
81 static DEFINE_MUTEX(register_count_mutex);
82 static DEFINE_MUTEX(video_list_lock);
83 static LIST_HEAD(video_bus_head);
84 static int acpi_video_bus_add(struct acpi_device *device);
85 static void acpi_video_bus_remove(struct acpi_device *device);
86 static void acpi_video_bus_notify(struct acpi_device *device, u32 event);
87 static void acpi_video_bus_register_backlight_work(struct work_struct *ignored);
88 static DECLARE_DELAYED_WORK(video_bus_register_backlight_work,
89 			    acpi_video_bus_register_backlight_work);
90 
91 /*
92  * Indices in the _BCL method response: the first two items are special,
93  * the rest are all supported levels.
94  *
95  * See page 575 of the ACPI spec 3.0
96  */
97 enum acpi_video_level_idx {
98 	ACPI_VIDEO_AC_LEVEL,		/* level when machine has full power */
99 	ACPI_VIDEO_BATTERY_LEVEL,	/* level when machine is on batteries */
100 	ACPI_VIDEO_FIRST_LEVEL,		/* actual supported levels begin here */
101 };
102 
103 static const struct acpi_device_id video_device_ids[] = {
104 	{ACPI_VIDEO_HID, 0},
105 	{"", 0},
106 };
107 MODULE_DEVICE_TABLE(acpi, video_device_ids);
108 
109 static struct acpi_driver acpi_video_bus = {
110 	.name = "video",
111 	.class = ACPI_VIDEO_CLASS,
112 	.ids = video_device_ids,
113 	.ops = {
114 		.add = acpi_video_bus_add,
115 		.remove = acpi_video_bus_remove,
116 		.notify = acpi_video_bus_notify,
117 		},
118 };
119 
120 struct acpi_video_bus_flags {
121 	u8 multihead:1;		/* can switch video heads */
122 	u8 rom:1;		/* can retrieve a video rom */
123 	u8 post:1;		/* can configure the head to */
124 	u8 reserved:5;
125 };
126 
127 struct acpi_video_bus_cap {
128 	u8 _DOS:1;		/* Enable/Disable output switching */
129 	u8 _DOD:1;		/* Enumerate all devices attached to display adapter */
130 	u8 _ROM:1;		/* Get ROM Data */
131 	u8 _GPD:1;		/* Get POST Device */
132 	u8 _SPD:1;		/* Set POST Device */
133 	u8 _VPO:1;		/* Video POST Options */
134 	u8 reserved:2;
135 };
136 
137 struct acpi_video_device_attrib {
138 	u32 display_index:4;	/* A zero-based instance of the Display */
139 	u32 display_port_attachment:4;	/* This field differentiates the display type */
140 	u32 display_type:4;	/* Describe the specific type in use */
141 	u32 vendor_specific:4;	/* Chipset Vendor Specific */
142 	u32 bios_can_detect:1;	/* BIOS can detect the device */
143 	u32 depend_on_vga:1;	/* Non-VGA output device whose power is related to
144 				   the VGA device. */
145 	u32 pipe_id:3;		/* For VGA multiple-head devices. */
146 	u32 reserved:10;	/* Must be 0 */
147 
148 	/*
149 	 * The device ID might not actually follow the scheme described by this
150 	 * struct acpi_video_device_attrib. If it does, then this bit
151 	 * device_id_scheme is set; otherwise, other fields should be ignored.
152 	 *
153 	 * (but also see the global flag device_id_scheme)
154 	 */
155 	u32 device_id_scheme:1;
156 };
157 
158 struct acpi_video_enumerated_device {
159 	union {
160 		u32 int_val;
161 		struct acpi_video_device_attrib attrib;
162 	} value;
163 	struct acpi_video_device *bind_info;
164 };
165 
166 struct acpi_video_bus {
167 	struct acpi_device *device;
168 	bool backlight_registered;
169 	u8 dos_setting;
170 	struct acpi_video_enumerated_device *attached_array;
171 	u8 attached_count;
172 	u8 child_count;
173 	struct acpi_video_bus_cap cap;
174 	struct acpi_video_bus_flags flags;
175 	struct list_head video_device_list;
176 	struct mutex device_list_lock;	/* protects video_device_list */
177 	struct list_head entry;
178 	struct input_dev *input;
179 	char phys[32];	/* for input device */
180 	struct notifier_block pm_nb;
181 };
182 
183 struct acpi_video_device_flags {
184 	u8 crt:1;
185 	u8 lcd:1;
186 	u8 tvout:1;
187 	u8 dvi:1;
188 	u8 bios:1;
189 	u8 unknown:1;
190 	u8 notify:1;
191 	u8 reserved:1;
192 };
193 
194 struct acpi_video_device_cap {
195 	u8 _ADR:1;		/* Return the unique ID */
196 	u8 _BCL:1;		/* Query list of brightness control levels supported */
197 	u8 _BCM:1;		/* Set the brightness level */
198 	u8 _BQC:1;		/* Get current brightness level */
199 	u8 _BCQ:1;		/* Some buggy BIOS uses _BCQ instead of _BQC */
200 	u8 _DDC:1;		/* Return the EDID for this device */
201 };
202 
203 struct acpi_video_device {
204 	unsigned long device_id;
205 	struct acpi_video_device_flags flags;
206 	struct acpi_video_device_cap cap;
207 	struct list_head entry;
208 	struct delayed_work switch_brightness_work;
209 	int switch_brightness_event;
210 	struct acpi_video_bus *video;
211 	struct acpi_device *dev;
212 	struct acpi_video_device_brightness *brightness;
213 	struct backlight_device *backlight;
214 	struct thermal_cooling_device *cooling_dev;
215 };
216 
217 static void acpi_video_device_notify(acpi_handle handle, u32 event, void *data);
218 static void acpi_video_device_rebind(struct acpi_video_bus *video);
219 static void acpi_video_device_bind(struct acpi_video_bus *video,
220 				   struct acpi_video_device *device);
221 static int acpi_video_device_enumerate(struct acpi_video_bus *video);
222 static int acpi_video_device_lcd_set_level(struct acpi_video_device *device,
223 			int level);
224 static int acpi_video_device_lcd_get_level_current(
225 			struct acpi_video_device *device,
226 			unsigned long long *level, bool raw);
227 static int acpi_video_get_next_level(struct acpi_video_device *device,
228 				     u32 level_current, u32 event);
229 static void acpi_video_switch_brightness(struct work_struct *work);
230 
231 /* backlight device sysfs support */
232 static int acpi_video_get_brightness(struct backlight_device *bd)
233 {
234 	unsigned long long cur_level;
235 	int i;
236 	struct acpi_video_device *vd = bl_get_data(bd);
237 
238 	if (acpi_video_device_lcd_get_level_current(vd, &cur_level, false))
239 		return -EINVAL;
240 	for (i = ACPI_VIDEO_FIRST_LEVEL; i < vd->brightness->count; i++) {
241 		if (vd->brightness->levels[i] == cur_level)
242 			return i - ACPI_VIDEO_FIRST_LEVEL;
243 	}
244 	return 0;
245 }
246 
247 static int acpi_video_set_brightness(struct backlight_device *bd)
248 {
249 	int request_level = bd->props.brightness + ACPI_VIDEO_FIRST_LEVEL;
250 	struct acpi_video_device *vd = bl_get_data(bd);
251 
252 	cancel_delayed_work(&vd->switch_brightness_work);
253 	return acpi_video_device_lcd_set_level(vd,
254 				vd->brightness->levels[request_level]);
255 }
256 
257 static const struct backlight_ops acpi_backlight_ops = {
258 	.get_brightness = acpi_video_get_brightness,
259 	.update_status  = acpi_video_set_brightness,
260 };
261 
262 /* thermal cooling device callbacks */
263 static int video_get_max_state(struct thermal_cooling_device *cooling_dev,
264 			       unsigned long *state)
265 {
266 	struct acpi_device *device = cooling_dev->devdata;
267 	struct acpi_video_device *video = acpi_driver_data(device);
268 
269 	*state = video->brightness->count - ACPI_VIDEO_FIRST_LEVEL - 1;
270 	return 0;
271 }
272 
273 static int video_get_cur_state(struct thermal_cooling_device *cooling_dev,
274 			       unsigned long *state)
275 {
276 	struct acpi_device *device = cooling_dev->devdata;
277 	struct acpi_video_device *video = acpi_driver_data(device);
278 	unsigned long long level;
279 	int offset;
280 
281 	if (acpi_video_device_lcd_get_level_current(video, &level, false))
282 		return -EINVAL;
283 	for (offset = ACPI_VIDEO_FIRST_LEVEL; offset < video->brightness->count;
284 	     offset++)
285 		if (level == video->brightness->levels[offset]) {
286 			*state = video->brightness->count - offset - 1;
287 			return 0;
288 		}
289 
290 	return -EINVAL;
291 }
292 
293 static int
294 video_set_cur_state(struct thermal_cooling_device *cooling_dev, unsigned long state)
295 {
296 	struct acpi_device *device = cooling_dev->devdata;
297 	struct acpi_video_device *video = acpi_driver_data(device);
298 	int level;
299 
300 	if (state >= video->brightness->count - ACPI_VIDEO_FIRST_LEVEL)
301 		return -EINVAL;
302 
303 	state = video->brightness->count - state;
304 	level = video->brightness->levels[state - 1];
305 	return acpi_video_device_lcd_set_level(video, level);
306 }
307 
308 static const struct thermal_cooling_device_ops video_cooling_ops = {
309 	.get_max_state = video_get_max_state,
310 	.get_cur_state = video_get_cur_state,
311 	.set_cur_state = video_set_cur_state,
312 };
313 
314 /*
315  * --------------------------------------------------------------------------
316  *                             Video Management
317  * --------------------------------------------------------------------------
318  */
319 
320 static int
321 acpi_video_device_lcd_query_levels(acpi_handle handle,
322 				   union acpi_object **levels)
323 {
324 	int status;
325 	struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
326 	union acpi_object *obj;
327 
328 
329 	*levels = NULL;
330 
331 	status = acpi_evaluate_object(handle, "_BCL", NULL, &buffer);
332 	if (ACPI_FAILURE(status))
333 		return status;
334 	obj = (union acpi_object *)buffer.pointer;
335 	if (!obj || (obj->type != ACPI_TYPE_PACKAGE)) {
336 		acpi_handle_info(handle, "Invalid _BCL data\n");
337 		status = -EFAULT;
338 		goto err;
339 	}
340 
341 	*levels = obj;
342 
343 	return 0;
344 
345 err:
346 	kfree(buffer.pointer);
347 
348 	return status;
349 }
350 
351 static int
352 acpi_video_device_lcd_set_level(struct acpi_video_device *device, int level)
353 {
354 	int status;
355 	int state;
356 
357 	status = acpi_execute_simple_method(device->dev->handle,
358 					    "_BCM", level);
359 	if (ACPI_FAILURE(status)) {
360 		acpi_handle_info(device->dev->handle, "_BCM evaluation failed\n");
361 		return -EIO;
362 	}
363 
364 	device->brightness->curr = level;
365 	for (state = ACPI_VIDEO_FIRST_LEVEL; state < device->brightness->count;
366 	     state++)
367 		if (level == device->brightness->levels[state]) {
368 			if (device->backlight)
369 				device->backlight->props.brightness =
370 					state - ACPI_VIDEO_FIRST_LEVEL;
371 			return 0;
372 		}
373 
374 	acpi_handle_info(device->dev->handle, "Current brightness invalid\n");
375 	return -EINVAL;
376 }
377 
378 /*
379  * For some buggy _BQC methods, we need to add a constant value to
380  * the _BQC return value to get the actual current brightness level
381  */
382 
383 static int bqc_offset_aml_bug_workaround;
384 static int video_set_bqc_offset(const struct dmi_system_id *d)
385 {
386 	bqc_offset_aml_bug_workaround = 9;
387 	return 0;
388 }
389 
390 static int video_set_device_id_scheme(const struct dmi_system_id *d)
391 {
392 	device_id_scheme = true;
393 	return 0;
394 }
395 
396 static int video_enable_only_lcd(const struct dmi_system_id *d)
397 {
398 	only_lcd = true;
399 	return 0;
400 }
401 
402 static int video_set_report_key_events(const struct dmi_system_id *id)
403 {
404 	if (report_key_events == -1)
405 		report_key_events = (uintptr_t)id->driver_data;
406 	return 0;
407 }
408 
409 static int video_hw_changes_brightness(
410 	const struct dmi_system_id *d)
411 {
412 	if (hw_changes_brightness == -1)
413 		hw_changes_brightness = 1;
414 	return 0;
415 }
416 
417 static const struct dmi_system_id video_dmi_table[] = {
418 	/*
419 	 * Broken _BQC workaround http://bugzilla.kernel.org/show_bug.cgi?id=13121
420 	 */
421 	{
422 	 .callback = video_set_bqc_offset,
423 	 .ident = "Acer Aspire 5720",
424 	 .matches = {
425 		DMI_MATCH(DMI_BOARD_VENDOR, "Acer"),
426 		DMI_MATCH(DMI_PRODUCT_NAME, "Aspire 5720"),
427 		},
428 	},
429 	{
430 	 .callback = video_set_bqc_offset,
431 	 .ident = "Acer Aspire 5710Z",
432 	 .matches = {
433 		DMI_MATCH(DMI_BOARD_VENDOR, "Acer"),
434 		DMI_MATCH(DMI_PRODUCT_NAME, "Aspire 5710Z"),
435 		},
436 	},
437 	{
438 	 .callback = video_set_bqc_offset,
439 	 .ident = "eMachines E510",
440 	 .matches = {
441 		DMI_MATCH(DMI_BOARD_VENDOR, "EMACHINES"),
442 		DMI_MATCH(DMI_PRODUCT_NAME, "eMachines E510"),
443 		},
444 	},
445 	{
446 	 .callback = video_set_bqc_offset,
447 	 .ident = "Acer Aspire 5315",
448 	 .matches = {
449 		DMI_MATCH(DMI_BOARD_VENDOR, "Acer"),
450 		DMI_MATCH(DMI_PRODUCT_NAME, "Aspire 5315"),
451 		},
452 	},
453 	{
454 	 .callback = video_set_bqc_offset,
455 	 .ident = "Acer Aspire 7720",
456 	 .matches = {
457 		DMI_MATCH(DMI_BOARD_VENDOR, "Acer"),
458 		DMI_MATCH(DMI_PRODUCT_NAME, "Aspire 7720"),
459 		},
460 	},
461 
462 	/*
463 	 * Some machine's _DOD IDs don't have bit 31(Device ID Scheme) set
464 	 * but the IDs actually follow the Device ID Scheme.
465 	 */
466 	{
467 	 /* https://bugzilla.kernel.org/show_bug.cgi?id=104121 */
468 	 .callback = video_set_device_id_scheme,
469 	 .ident = "ESPRIMO Mobile M9410",
470 	 .matches = {
471 		DMI_MATCH(DMI_SYS_VENDOR, "FUJITSU SIEMENS"),
472 		DMI_MATCH(DMI_PRODUCT_NAME, "ESPRIMO Mobile M9410"),
473 		},
474 	},
475 	/*
476 	 * Some machines have multiple video output devices, but only the one
477 	 * that is the type of LCD can do the backlight control so we should not
478 	 * register backlight interface for other video output devices.
479 	 */
480 	{
481 	 /* https://bugzilla.kernel.org/show_bug.cgi?id=104121 */
482 	 .callback = video_enable_only_lcd,
483 	 .ident = "ESPRIMO Mobile M9410",
484 	 .matches = {
485 		DMI_MATCH(DMI_SYS_VENDOR, "FUJITSU SIEMENS"),
486 		DMI_MATCH(DMI_PRODUCT_NAME, "ESPRIMO Mobile M9410"),
487 		},
488 	},
489 	/*
490 	 * Some machines report wrong key events on the acpi-bus, suppress
491 	 * key event reporting on these.  Note this is only intended to work
492 	 * around events which are plain wrong. In some cases we get double
493 	 * events, in this case acpi-video is considered the canonical source
494 	 * and the events from the other source should be filtered. E.g.
495 	 * by calling acpi_video_handles_brightness_key_presses() from the
496 	 * vendor acpi/wmi driver or by using /lib/udev/hwdb.d/60-keyboard.hwdb
497 	 */
498 	{
499 	 .callback = video_set_report_key_events,
500 	 .driver_data = (void *)((uintptr_t)REPORT_OUTPUT_KEY_EVENTS),
501 	 .ident = "Dell Vostro V131",
502 	 .matches = {
503 		DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
504 		DMI_MATCH(DMI_PRODUCT_NAME, "Vostro V131"),
505 		},
506 	},
507 	{
508 	 .callback = video_set_report_key_events,
509 	 .driver_data = (void *)((uintptr_t)REPORT_BRIGHTNESS_KEY_EVENTS),
510 	 .ident = "Dell Vostro 3350",
511 	 .matches = {
512 		DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
513 		DMI_MATCH(DMI_PRODUCT_NAME, "Vostro 3350"),
514 		},
515 	},
516 	/*
517 	 * Some machines change the brightness themselves when a brightness
518 	 * hotkey gets pressed, despite us telling them not to. In this case
519 	 * acpi_video_device_notify() should only call backlight_force_update(
520 	 * BACKLIGHT_UPDATE_HOTKEY) and not do anything else.
521 	 */
522 	{
523 	 /* https://bugzilla.kernel.org/show_bug.cgi?id=204077 */
524 	 .callback = video_hw_changes_brightness,
525 	 .ident = "Packard Bell EasyNote MZ35",
526 	 .matches = {
527 		DMI_MATCH(DMI_SYS_VENDOR, "Packard Bell"),
528 		DMI_MATCH(DMI_PRODUCT_NAME, "EasyNote MZ35"),
529 		},
530 	},
531 	{}
532 };
533 
534 static unsigned long long
535 acpi_video_bqc_value_to_level(struct acpi_video_device *device,
536 			      unsigned long long bqc_value)
537 {
538 	unsigned long long level;
539 
540 	if (device->brightness->flags._BQC_use_index) {
541 		/*
542 		 * _BQC returns an index that doesn't account for the first 2
543 		 * items with special meaning (see enum acpi_video_level_idx),
544 		 * so we need to compensate for that by offsetting ourselves
545 		 */
546 		if (device->brightness->flags._BCL_reversed)
547 			bqc_value = device->brightness->count -
548 				ACPI_VIDEO_FIRST_LEVEL - 1 - bqc_value;
549 
550 		level = device->brightness->levels[bqc_value +
551 						   ACPI_VIDEO_FIRST_LEVEL];
552 	} else {
553 		level = bqc_value;
554 	}
555 
556 	level += bqc_offset_aml_bug_workaround;
557 
558 	return level;
559 }
560 
561 static int
562 acpi_video_device_lcd_get_level_current(struct acpi_video_device *device,
563 					unsigned long long *level, bool raw)
564 {
565 	acpi_status status = AE_OK;
566 	int i;
567 
568 	if (device->cap._BQC || device->cap._BCQ) {
569 		char *buf = device->cap._BQC ? "_BQC" : "_BCQ";
570 
571 		status = acpi_evaluate_integer(device->dev->handle, buf,
572 						NULL, level);
573 		if (ACPI_SUCCESS(status)) {
574 			if (raw) {
575 				/*
576 				 * Caller has indicated he wants the raw
577 				 * value returned by _BQC, so don't furtherly
578 				 * mess with the value.
579 				 */
580 				return 0;
581 			}
582 
583 			*level = acpi_video_bqc_value_to_level(device, *level);
584 
585 			for (i = ACPI_VIDEO_FIRST_LEVEL;
586 			     i < device->brightness->count; i++)
587 				if (device->brightness->levels[i] == *level) {
588 					device->brightness->curr = *level;
589 					return 0;
590 				}
591 			/*
592 			 * BQC returned an invalid level.
593 			 * Stop using it.
594 			 */
595 			acpi_handle_info(device->dev->handle,
596 					 "%s returned an invalid level", buf);
597 			device->cap._BQC = device->cap._BCQ = 0;
598 		} else {
599 			/*
600 			 * Fixme:
601 			 * should we return an error or ignore this failure?
602 			 * dev->brightness->curr is a cached value which stores
603 			 * the correct current backlight level in most cases.
604 			 * ACPI video backlight still works w/ buggy _BQC.
605 			 * http://bugzilla.kernel.org/show_bug.cgi?id=12233
606 			 */
607 			acpi_handle_info(device->dev->handle,
608 					 "%s evaluation failed", buf);
609 			device->cap._BQC = device->cap._BCQ = 0;
610 		}
611 	}
612 
613 	*level = device->brightness->curr;
614 	return 0;
615 }
616 
617 static int
618 acpi_video_device_EDID(struct acpi_video_device *device,
619 		       union acpi_object **edid, ssize_t length)
620 {
621 	int status;
622 	struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
623 	union acpi_object *obj;
624 	union acpi_object arg0 = { ACPI_TYPE_INTEGER };
625 	struct acpi_object_list args = { 1, &arg0 };
626 
627 
628 	*edid = NULL;
629 
630 	if (!device)
631 		return -ENODEV;
632 	if (length == 128)
633 		arg0.integer.value = 1;
634 	else if (length == 256)
635 		arg0.integer.value = 2;
636 	else
637 		return -EINVAL;
638 
639 	status = acpi_evaluate_object(device->dev->handle, "_DDC", &args, &buffer);
640 	if (ACPI_FAILURE(status))
641 		return -ENODEV;
642 
643 	obj = buffer.pointer;
644 
645 	if (obj && obj->type == ACPI_TYPE_BUFFER)
646 		*edid = obj;
647 	else {
648 		acpi_handle_info(device->dev->handle, "Invalid _DDC data\n");
649 		status = -EFAULT;
650 		kfree(obj);
651 	}
652 
653 	return status;
654 }
655 
656 /* bus */
657 
658 /*
659  *  Arg:
660  *	video		: video bus device pointer
661  *	bios_flag	:
662  *		0.	The system BIOS should NOT automatically switch(toggle)
663  *			the active display output.
664  *		1.	The system BIOS should automatically switch (toggle) the
665  *			active display output. No switch event.
666  *		2.	The _DGS value should be locked.
667  *		3.	The system BIOS should not automatically switch (toggle) the
668  *			active display output, but instead generate the display switch
669  *			event notify code.
670  *	lcd_flag	:
671  *		0.	The system BIOS should automatically control the brightness level
672  *			of the LCD when:
673  *			- the power changes from AC to DC (ACPI appendix B)
674  *			- a brightness hotkey gets pressed (implied by Win7/8 backlight docs)
675  *		1.	The system BIOS should NOT automatically control the brightness
676  *			level of the LCD when:
677  *			- the power changes from AC to DC (ACPI appendix B)
678  *			- a brightness hotkey gets pressed (implied by Win7/8 backlight docs)
679  *  Return Value:
680  *		-EINVAL	wrong arg.
681  */
682 
683 static int
684 acpi_video_bus_DOS(struct acpi_video_bus *video, int bios_flag, int lcd_flag)
685 {
686 	acpi_status status;
687 
688 	if (!video->cap._DOS)
689 		return 0;
690 
691 	if (bios_flag < 0 || bios_flag > 3 || lcd_flag < 0 || lcd_flag > 1)
692 		return -EINVAL;
693 	video->dos_setting = (lcd_flag << 2) | bios_flag;
694 	status = acpi_execute_simple_method(video->device->handle, "_DOS",
695 					    (lcd_flag << 2) | bios_flag);
696 	if (ACPI_FAILURE(status))
697 		return -EIO;
698 
699 	return 0;
700 }
701 
702 /*
703  * Simple comparison function used to sort backlight levels.
704  */
705 
706 static int
707 acpi_video_cmp_level(const void *a, const void *b)
708 {
709 	return *(int *)a - *(int *)b;
710 }
711 
712 /*
713  * Decides if _BQC/_BCQ for this system is usable
714  *
715  * We do this by changing the level first and then read out the current
716  * brightness level, if the value does not match, find out if it is using
717  * index. If not, clear the _BQC/_BCQ capability.
718  */
719 static int acpi_video_bqc_quirk(struct acpi_video_device *device,
720 				int max_level, int current_level)
721 {
722 	struct acpi_video_device_brightness *br = device->brightness;
723 	int result;
724 	unsigned long long level;
725 	int test_level;
726 
727 	/* don't mess with existing known broken systems */
728 	if (bqc_offset_aml_bug_workaround)
729 		return 0;
730 
731 	/*
732 	 * Some systems always report current brightness level as maximum
733 	 * through _BQC, we need to test another value for them. However,
734 	 * there is a subtlety:
735 	 *
736 	 * If the _BCL package ordering is descending, the first level
737 	 * (br->levels[2]) is likely to be 0, and if the number of levels
738 	 * matches the number of steps, we might confuse a returned level to
739 	 * mean the index.
740 	 *
741 	 * For example:
742 	 *
743 	 *     current_level = max_level = 100
744 	 *     test_level = 0
745 	 *     returned level = 100
746 	 *
747 	 * In this case 100 means the level, not the index, and _BCM failed.
748 	 * Still, if the _BCL package ordering is descending, the index of
749 	 * level 0 is also 100, so we assume _BQC is indexed, when it's not.
750 	 *
751 	 * This causes all _BQC calls to return bogus values causing weird
752 	 * behavior from the user's perspective.  For example:
753 	 *
754 	 * xbacklight -set 10; xbacklight -set 20;
755 	 *
756 	 * would flash to 90% and then slowly down to the desired level (20).
757 	 *
758 	 * The solution is simple; test anything other than the first level
759 	 * (e.g. 1).
760 	 */
761 	test_level = current_level == max_level
762 		? br->levels[ACPI_VIDEO_FIRST_LEVEL + 1]
763 		: max_level;
764 
765 	result = acpi_video_device_lcd_set_level(device, test_level);
766 	if (result)
767 		return result;
768 
769 	result = acpi_video_device_lcd_get_level_current(device, &level, true);
770 	if (result)
771 		return result;
772 
773 	if (level != test_level) {
774 		/* buggy _BQC found, need to find out if it uses index */
775 		if (level < br->count) {
776 			if (br->flags._BCL_reversed)
777 				level = br->count - ACPI_VIDEO_FIRST_LEVEL - 1 - level;
778 			if (br->levels[level + ACPI_VIDEO_FIRST_LEVEL] == test_level)
779 				br->flags._BQC_use_index = 1;
780 		}
781 
782 		if (!br->flags._BQC_use_index)
783 			device->cap._BQC = device->cap._BCQ = 0;
784 	}
785 
786 	return 0;
787 }
788 
789 int acpi_video_get_levels(struct acpi_device *device,
790 			  struct acpi_video_device_brightness **dev_br,
791 			  int *pmax_level)
792 {
793 	union acpi_object *obj = NULL;
794 	int i, max_level = 0, count = 0, level_ac_battery = 0;
795 	union acpi_object *o;
796 	struct acpi_video_device_brightness *br = NULL;
797 	int result = 0;
798 	u32 value;
799 
800 	if (ACPI_FAILURE(acpi_video_device_lcd_query_levels(device->handle, &obj))) {
801 		acpi_handle_debug(device->handle,
802 				  "Could not query available LCD brightness level\n");
803 		result = -ENODEV;
804 		goto out;
805 	}
806 
807 	if (obj->package.count < ACPI_VIDEO_FIRST_LEVEL) {
808 		result = -EINVAL;
809 		goto out;
810 	}
811 
812 	br = kzalloc(sizeof(*br), GFP_KERNEL);
813 	if (!br) {
814 		result = -ENOMEM;
815 		goto out;
816 	}
817 
818 	/*
819 	 * Note that we have to reserve 2 extra items (ACPI_VIDEO_FIRST_LEVEL),
820 	 * in order to account for buggy BIOS which don't export the first two
821 	 * special levels (see below)
822 	 */
823 	br->levels = kmalloc_array(obj->package.count + ACPI_VIDEO_FIRST_LEVEL,
824 				   sizeof(*br->levels),
825 				   GFP_KERNEL);
826 	if (!br->levels) {
827 		result = -ENOMEM;
828 		goto out_free;
829 	}
830 
831 	for (i = 0; i < obj->package.count; i++) {
832 		o = (union acpi_object *)&obj->package.elements[i];
833 		if (o->type != ACPI_TYPE_INTEGER) {
834 			acpi_handle_info(device->handle, "Invalid data\n");
835 			continue;
836 		}
837 		value = (u32) o->integer.value;
838 		/* Skip duplicate entries */
839 		if (count > ACPI_VIDEO_FIRST_LEVEL
840 		    && br->levels[count - 1] == value)
841 			continue;
842 
843 		br->levels[count] = value;
844 
845 		if (br->levels[count] > max_level)
846 			max_level = br->levels[count];
847 		count++;
848 	}
849 
850 	/*
851 	 * some buggy BIOS don't export the levels
852 	 * when machine is on AC/Battery in _BCL package.
853 	 * In this case, the first two elements in _BCL packages
854 	 * are also supported brightness levels that OS should take care of.
855 	 */
856 	for (i = ACPI_VIDEO_FIRST_LEVEL; i < count; i++) {
857 		if (br->levels[i] == br->levels[ACPI_VIDEO_AC_LEVEL])
858 			level_ac_battery++;
859 		if (br->levels[i] == br->levels[ACPI_VIDEO_BATTERY_LEVEL])
860 			level_ac_battery++;
861 	}
862 
863 	if (level_ac_battery < ACPI_VIDEO_FIRST_LEVEL) {
864 		level_ac_battery = ACPI_VIDEO_FIRST_LEVEL - level_ac_battery;
865 		br->flags._BCL_no_ac_battery_levels = 1;
866 		for (i = (count - 1 + level_ac_battery);
867 		     i >= ACPI_VIDEO_FIRST_LEVEL; i--)
868 			br->levels[i] = br->levels[i - level_ac_battery];
869 		count += level_ac_battery;
870 	} else if (level_ac_battery > ACPI_VIDEO_FIRST_LEVEL)
871 		acpi_handle_info(device->handle,
872 				 "Too many duplicates in _BCL package");
873 
874 	/* Check if the _BCL package is in a reversed order */
875 	if (max_level == br->levels[ACPI_VIDEO_FIRST_LEVEL]) {
876 		br->flags._BCL_reversed = 1;
877 		sort(&br->levels[ACPI_VIDEO_FIRST_LEVEL],
878 		     count - ACPI_VIDEO_FIRST_LEVEL,
879 		     sizeof(br->levels[ACPI_VIDEO_FIRST_LEVEL]),
880 		     acpi_video_cmp_level, NULL);
881 	} else if (max_level != br->levels[count - 1])
882 		acpi_handle_info(device->handle,
883 				 "Found unordered _BCL package");
884 
885 	br->count = count;
886 	*dev_br = br;
887 	if (pmax_level)
888 		*pmax_level = max_level;
889 
890 out:
891 	kfree(obj);
892 	return result;
893 out_free:
894 	kfree(br);
895 	goto out;
896 }
897 EXPORT_SYMBOL(acpi_video_get_levels);
898 
899 /*
900  *  Arg:
901  *	device	: video output device (LCD, CRT, ..)
902  *
903  *  Return Value:
904  *	Maximum brightness level
905  *
906  *  Allocate and initialize device->brightness.
907  */
908 
909 static int
910 acpi_video_init_brightness(struct acpi_video_device *device)
911 {
912 	int i, max_level = 0;
913 	unsigned long long level, level_old;
914 	struct acpi_video_device_brightness *br = NULL;
915 	int result;
916 
917 	result = acpi_video_get_levels(device->dev, &br, &max_level);
918 	if (result)
919 		return result;
920 	device->brightness = br;
921 
922 	/* _BQC uses INDEX while _BCL uses VALUE in some laptops */
923 	br->curr = level = max_level;
924 
925 	if (!device->cap._BQC)
926 		goto set_level;
927 
928 	result = acpi_video_device_lcd_get_level_current(device,
929 							 &level_old, true);
930 	if (result)
931 		goto out_free_levels;
932 
933 	result = acpi_video_bqc_quirk(device, max_level, level_old);
934 	if (result)
935 		goto out_free_levels;
936 	/*
937 	 * cap._BQC may get cleared due to _BQC is found to be broken
938 	 * in acpi_video_bqc_quirk, so check again here.
939 	 */
940 	if (!device->cap._BQC)
941 		goto set_level;
942 
943 	level = acpi_video_bqc_value_to_level(device, level_old);
944 	/*
945 	 * On some buggy laptops, _BQC returns an uninitialized
946 	 * value when invoked for the first time, i.e.
947 	 * level_old is invalid (no matter whether it's a level
948 	 * or an index). Set the backlight to max_level in this case.
949 	 */
950 	for (i = ACPI_VIDEO_FIRST_LEVEL; i < br->count; i++)
951 		if (level == br->levels[i])
952 			break;
953 	if (i == br->count || !level)
954 		level = max_level;
955 
956 set_level:
957 	result = acpi_video_device_lcd_set_level(device, level);
958 	if (result)
959 		goto out_free_levels;
960 
961 	acpi_handle_debug(device->dev->handle, "found %d brightness levels\n",
962 			  br->count - ACPI_VIDEO_FIRST_LEVEL);
963 
964 	return 0;
965 
966 out_free_levels:
967 	kfree(br->levels);
968 	kfree(br);
969 	device->brightness = NULL;
970 	return result;
971 }
972 
973 /*
974  *  Arg:
975  *	device	: video output device (LCD, CRT, ..)
976  *
977  *  Return Value:
978  *	None
979  *
980  *  Find out all required AML methods defined under the output
981  *  device.
982  */
983 
984 static void acpi_video_device_find_cap(struct acpi_video_device *device)
985 {
986 	if (acpi_has_method(device->dev->handle, "_ADR"))
987 		device->cap._ADR = 1;
988 	if (acpi_has_method(device->dev->handle, "_BCL"))
989 		device->cap._BCL = 1;
990 	if (acpi_has_method(device->dev->handle, "_BCM"))
991 		device->cap._BCM = 1;
992 	if (acpi_has_method(device->dev->handle, "_BQC")) {
993 		device->cap._BQC = 1;
994 	} else if (acpi_has_method(device->dev->handle, "_BCQ")) {
995 		acpi_handle_info(device->dev->handle,
996 				 "_BCQ is used instead of _BQC\n");
997 		device->cap._BCQ = 1;
998 	}
999 
1000 	if (acpi_has_method(device->dev->handle, "_DDC"))
1001 		device->cap._DDC = 1;
1002 }
1003 
1004 /*
1005  *  Arg:
1006  *	device	: video output device (VGA)
1007  *
1008  *  Return Value:
1009  *	None
1010  *
1011  *  Find out all required AML methods defined under the video bus device.
1012  */
1013 
1014 static void acpi_video_bus_find_cap(struct acpi_video_bus *video)
1015 {
1016 	if (acpi_has_method(video->device->handle, "_DOS"))
1017 		video->cap._DOS = 1;
1018 	if (acpi_has_method(video->device->handle, "_DOD"))
1019 		video->cap._DOD = 1;
1020 	if (acpi_has_method(video->device->handle, "_ROM"))
1021 		video->cap._ROM = 1;
1022 	if (acpi_has_method(video->device->handle, "_GPD"))
1023 		video->cap._GPD = 1;
1024 	if (acpi_has_method(video->device->handle, "_SPD"))
1025 		video->cap._SPD = 1;
1026 	if (acpi_has_method(video->device->handle, "_VPO"))
1027 		video->cap._VPO = 1;
1028 }
1029 
1030 /*
1031  * Check whether the video bus device has required AML method to
1032  * support the desired features
1033  */
1034 
1035 static int acpi_video_bus_check(struct acpi_video_bus *video)
1036 {
1037 	acpi_status status = -ENOENT;
1038 	struct pci_dev *dev;
1039 
1040 	if (!video)
1041 		return -EINVAL;
1042 
1043 	dev = acpi_get_pci_dev(video->device->handle);
1044 	if (!dev)
1045 		return -ENODEV;
1046 	pci_dev_put(dev);
1047 
1048 	/*
1049 	 * Since there is no HID, CID and so on for VGA driver, we have
1050 	 * to check well known required nodes.
1051 	 */
1052 
1053 	/* Does this device support video switching? */
1054 	if (video->cap._DOS || video->cap._DOD) {
1055 		if (!video->cap._DOS) {
1056 			pr_info(FW_BUG "ACPI(%s) defines _DOD but not _DOS\n",
1057 				acpi_device_bid(video->device));
1058 		}
1059 		video->flags.multihead = 1;
1060 		status = 0;
1061 	}
1062 
1063 	/* Does this device support retrieving a video ROM? */
1064 	if (video->cap._ROM) {
1065 		video->flags.rom = 1;
1066 		status = 0;
1067 	}
1068 
1069 	/* Does this device support configuring which video device to POST? */
1070 	if (video->cap._GPD && video->cap._SPD && video->cap._VPO) {
1071 		video->flags.post = 1;
1072 		status = 0;
1073 	}
1074 
1075 	return status;
1076 }
1077 
1078 /*
1079  * --------------------------------------------------------------------------
1080  *                               Driver Interface
1081  * --------------------------------------------------------------------------
1082  */
1083 
1084 /* device interface */
1085 static struct acpi_video_device_attrib *
1086 acpi_video_get_device_attr(struct acpi_video_bus *video, unsigned long device_id)
1087 {
1088 	struct acpi_video_enumerated_device *ids;
1089 	int i;
1090 
1091 	for (i = 0; i < video->attached_count; i++) {
1092 		ids = &video->attached_array[i];
1093 		if ((ids->value.int_val & 0xffff) == device_id)
1094 			return &ids->value.attrib;
1095 	}
1096 
1097 	return NULL;
1098 }
1099 
1100 static int
1101 acpi_video_get_device_type(struct acpi_video_bus *video,
1102 			   unsigned long device_id)
1103 {
1104 	struct acpi_video_enumerated_device *ids;
1105 	int i;
1106 
1107 	for (i = 0; i < video->attached_count; i++) {
1108 		ids = &video->attached_array[i];
1109 		if ((ids->value.int_val & 0xffff) == device_id)
1110 			return ids->value.int_val;
1111 	}
1112 
1113 	return 0;
1114 }
1115 
1116 static int acpi_video_bus_get_one_device(struct acpi_device *device, void *arg)
1117 {
1118 	struct acpi_video_bus *video = arg;
1119 	struct acpi_video_device_attrib *attribute;
1120 	struct acpi_video_device *data;
1121 	unsigned long long device_id;
1122 	acpi_status status;
1123 	int device_type;
1124 
1125 	status = acpi_evaluate_integer(device->handle, "_ADR", NULL, &device_id);
1126 	/* Skip devices without _ADR instead of failing. */
1127 	if (ACPI_FAILURE(status))
1128 		goto exit;
1129 
1130 	data = kzalloc(sizeof(struct acpi_video_device), GFP_KERNEL);
1131 	if (!data) {
1132 		dev_dbg(&device->dev, "Cannot attach\n");
1133 		return -ENOMEM;
1134 	}
1135 
1136 	strcpy(acpi_device_name(device), ACPI_VIDEO_DEVICE_NAME);
1137 	strcpy(acpi_device_class(device), ACPI_VIDEO_CLASS);
1138 	device->driver_data = data;
1139 
1140 	data->device_id = device_id;
1141 	data->video = video;
1142 	data->dev = device;
1143 	INIT_DELAYED_WORK(&data->switch_brightness_work,
1144 			  acpi_video_switch_brightness);
1145 
1146 	attribute = acpi_video_get_device_attr(video, device_id);
1147 
1148 	if (attribute && (attribute->device_id_scheme || device_id_scheme)) {
1149 		switch (attribute->display_type) {
1150 		case ACPI_VIDEO_DISPLAY_CRT:
1151 			data->flags.crt = 1;
1152 			break;
1153 		case ACPI_VIDEO_DISPLAY_TV:
1154 			data->flags.tvout = 1;
1155 			break;
1156 		case ACPI_VIDEO_DISPLAY_DVI:
1157 			data->flags.dvi = 1;
1158 			break;
1159 		case ACPI_VIDEO_DISPLAY_LCD:
1160 			data->flags.lcd = 1;
1161 			break;
1162 		default:
1163 			data->flags.unknown = 1;
1164 			break;
1165 		}
1166 		if (attribute->bios_can_detect)
1167 			data->flags.bios = 1;
1168 	} else {
1169 		/* Check for legacy IDs */
1170 		device_type = acpi_video_get_device_type(video, device_id);
1171 		/* Ignore bits 16 and 18-20 */
1172 		switch (device_type & 0xffe2ffff) {
1173 		case ACPI_VIDEO_DISPLAY_LEGACY_MONITOR:
1174 			data->flags.crt = 1;
1175 			break;
1176 		case ACPI_VIDEO_DISPLAY_LEGACY_PANEL:
1177 			data->flags.lcd = 1;
1178 			break;
1179 		case ACPI_VIDEO_DISPLAY_LEGACY_TV:
1180 			data->flags.tvout = 1;
1181 			break;
1182 		default:
1183 			data->flags.unknown = 1;
1184 		}
1185 	}
1186 
1187 	acpi_video_device_bind(video, data);
1188 	acpi_video_device_find_cap(data);
1189 
1190 	if (data->cap._BCM && data->cap._BCL)
1191 		may_report_brightness_keys = true;
1192 
1193 	mutex_lock(&video->device_list_lock);
1194 	list_add_tail(&data->entry, &video->video_device_list);
1195 	mutex_unlock(&video->device_list_lock);
1196 
1197 exit:
1198 	video->child_count++;
1199 	return 0;
1200 }
1201 
1202 /*
1203  *  Arg:
1204  *	video	: video bus device
1205  *
1206  *  Return:
1207  *	none
1208  *
1209  *  Enumerate the video device list of the video bus,
1210  *  bind the ids with the corresponding video devices
1211  *  under the video bus.
1212  */
1213 
1214 static void acpi_video_device_rebind(struct acpi_video_bus *video)
1215 {
1216 	struct acpi_video_device *dev;
1217 
1218 	mutex_lock(&video->device_list_lock);
1219 
1220 	list_for_each_entry(dev, &video->video_device_list, entry)
1221 		acpi_video_device_bind(video, dev);
1222 
1223 	mutex_unlock(&video->device_list_lock);
1224 }
1225 
1226 /*
1227  *  Arg:
1228  *	video	: video bus device
1229  *	device	: video output device under the video
1230  *		bus
1231  *
1232  *  Return:
1233  *	none
1234  *
1235  *  Bind the ids with the corresponding video devices
1236  *  under the video bus.
1237  */
1238 
1239 static void
1240 acpi_video_device_bind(struct acpi_video_bus *video,
1241 		       struct acpi_video_device *device)
1242 {
1243 	struct acpi_video_enumerated_device *ids;
1244 	int i;
1245 
1246 	for (i = 0; i < video->attached_count; i++) {
1247 		ids = &video->attached_array[i];
1248 		if (device->device_id == (ids->value.int_val & 0xffff)) {
1249 			ids->bind_info = device;
1250 			acpi_handle_debug(video->device->handle, "%s: %d\n",
1251 					  __func__, i);
1252 		}
1253 	}
1254 }
1255 
1256 static bool acpi_video_device_in_dod(struct acpi_video_device *device)
1257 {
1258 	struct acpi_video_bus *video = device->video;
1259 	int i;
1260 
1261 	/*
1262 	 * If we have a broken _DOD or we have more than 8 output devices
1263 	 * under the graphics controller node that we can't proper deal with
1264 	 * in the operation region code currently, no need to test.
1265 	 */
1266 	if (!video->attached_count || video->child_count > 8)
1267 		return true;
1268 
1269 	for (i = 0; i < video->attached_count; i++) {
1270 		if ((video->attached_array[i].value.int_val & 0xfff) ==
1271 		    (device->device_id & 0xfff))
1272 			return true;
1273 	}
1274 
1275 	return false;
1276 }
1277 
1278 /*
1279  *  Arg:
1280  *	video	: video bus device
1281  *
1282  *  Return:
1283  *	< 0	: error
1284  *
1285  *  Call _DOD to enumerate all devices attached to display adapter
1286  *
1287  */
1288 
1289 static int acpi_video_device_enumerate(struct acpi_video_bus *video)
1290 {
1291 	int status;
1292 	int count;
1293 	int i;
1294 	struct acpi_video_enumerated_device *active_list;
1295 	struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
1296 	union acpi_object *dod = NULL;
1297 	union acpi_object *obj;
1298 
1299 	if (!video->cap._DOD)
1300 		return AE_NOT_EXIST;
1301 
1302 	status = acpi_evaluate_object(video->device->handle, "_DOD", NULL, &buffer);
1303 	if (ACPI_FAILURE(status)) {
1304 		acpi_handle_info(video->device->handle,
1305 				 "_DOD evaluation failed: %s\n",
1306 				 acpi_format_exception(status));
1307 		return status;
1308 	}
1309 
1310 	dod = buffer.pointer;
1311 	if (!dod || (dod->type != ACPI_TYPE_PACKAGE)) {
1312 		acpi_handle_info(video->device->handle, "Invalid _DOD data\n");
1313 		status = -EFAULT;
1314 		goto out;
1315 	}
1316 
1317 	acpi_handle_debug(video->device->handle, "Found %d video heads in _DOD\n",
1318 			  dod->package.count);
1319 
1320 	active_list = kcalloc(1 + dod->package.count,
1321 			      sizeof(struct acpi_video_enumerated_device),
1322 			      GFP_KERNEL);
1323 	if (!active_list) {
1324 		status = -ENOMEM;
1325 		goto out;
1326 	}
1327 
1328 	count = 0;
1329 	for (i = 0; i < dod->package.count; i++) {
1330 		obj = &dod->package.elements[i];
1331 
1332 		if (obj->type != ACPI_TYPE_INTEGER) {
1333 			acpi_handle_info(video->device->handle,
1334 					 "Invalid _DOD data in element %d\n", i);
1335 			continue;
1336 		}
1337 
1338 		active_list[count].value.int_val = obj->integer.value;
1339 		active_list[count].bind_info = NULL;
1340 
1341 		acpi_handle_debug(video->device->handle,
1342 				  "_DOD element[%d] = %d\n", i,
1343 				  (int)obj->integer.value);
1344 
1345 		count++;
1346 	}
1347 
1348 	kfree(video->attached_array);
1349 
1350 	video->attached_array = active_list;
1351 	video->attached_count = count;
1352 
1353 out:
1354 	kfree(buffer.pointer);
1355 	return status;
1356 }
1357 
1358 static int
1359 acpi_video_get_next_level(struct acpi_video_device *device,
1360 			  u32 level_current, u32 event)
1361 {
1362 	int min, max, min_above, max_below, i, l, delta = 255;
1363 	max = max_below = 0;
1364 	min = min_above = 255;
1365 	/* Find closest level to level_current */
1366 	for (i = ACPI_VIDEO_FIRST_LEVEL; i < device->brightness->count; i++) {
1367 		l = device->brightness->levels[i];
1368 		if (abs(l - level_current) < abs(delta)) {
1369 			delta = l - level_current;
1370 			if (!delta)
1371 				break;
1372 		}
1373 	}
1374 	/* Adjust level_current to closest available level */
1375 	level_current += delta;
1376 	for (i = ACPI_VIDEO_FIRST_LEVEL; i < device->brightness->count; i++) {
1377 		l = device->brightness->levels[i];
1378 		if (l < min)
1379 			min = l;
1380 		if (l > max)
1381 			max = l;
1382 		if (l < min_above && l > level_current)
1383 			min_above = l;
1384 		if (l > max_below && l < level_current)
1385 			max_below = l;
1386 	}
1387 
1388 	switch (event) {
1389 	case ACPI_VIDEO_NOTIFY_CYCLE_BRIGHTNESS:
1390 		return (level_current < max) ? min_above : min;
1391 	case ACPI_VIDEO_NOTIFY_INC_BRIGHTNESS:
1392 		return (level_current < max) ? min_above : max;
1393 	case ACPI_VIDEO_NOTIFY_DEC_BRIGHTNESS:
1394 		return (level_current > min) ? max_below : min;
1395 	case ACPI_VIDEO_NOTIFY_ZERO_BRIGHTNESS:
1396 	case ACPI_VIDEO_NOTIFY_DISPLAY_OFF:
1397 		return 0;
1398 	default:
1399 		return level_current;
1400 	}
1401 }
1402 
1403 static void
1404 acpi_video_switch_brightness(struct work_struct *work)
1405 {
1406 	struct acpi_video_device *device = container_of(to_delayed_work(work),
1407 			     struct acpi_video_device, switch_brightness_work);
1408 	unsigned long long level_current, level_next;
1409 	int event = device->switch_brightness_event;
1410 	int result = -EINVAL;
1411 
1412 	/* no warning message if acpi_backlight=vendor or a quirk is used */
1413 	if (!device->backlight)
1414 		return;
1415 
1416 	if (!device->brightness)
1417 		goto out;
1418 
1419 	result = acpi_video_device_lcd_get_level_current(device,
1420 							 &level_current,
1421 							 false);
1422 	if (result)
1423 		goto out;
1424 
1425 	level_next = acpi_video_get_next_level(device, level_current, event);
1426 
1427 	result = acpi_video_device_lcd_set_level(device, level_next);
1428 
1429 	if (!result)
1430 		backlight_force_update(device->backlight,
1431 				       BACKLIGHT_UPDATE_HOTKEY);
1432 
1433 out:
1434 	if (result)
1435 		acpi_handle_info(device->dev->handle,
1436 				 "Failed to switch brightness\n");
1437 }
1438 
1439 int acpi_video_get_edid(struct acpi_device *device, int type, int device_id,
1440 			void **edid)
1441 {
1442 	struct acpi_video_bus *video;
1443 	struct acpi_video_device *video_device;
1444 	union acpi_object *buffer = NULL;
1445 	acpi_status status;
1446 	int i, length;
1447 
1448 	if (!device || !acpi_driver_data(device))
1449 		return -EINVAL;
1450 
1451 	video = acpi_driver_data(device);
1452 
1453 	for (i = 0; i < video->attached_count; i++) {
1454 		video_device = video->attached_array[i].bind_info;
1455 		length = 256;
1456 
1457 		if (!video_device)
1458 			continue;
1459 
1460 		if (!video_device->cap._DDC)
1461 			continue;
1462 
1463 		if (type) {
1464 			switch (type) {
1465 			case ACPI_VIDEO_DISPLAY_CRT:
1466 				if (!video_device->flags.crt)
1467 					continue;
1468 				break;
1469 			case ACPI_VIDEO_DISPLAY_TV:
1470 				if (!video_device->flags.tvout)
1471 					continue;
1472 				break;
1473 			case ACPI_VIDEO_DISPLAY_DVI:
1474 				if (!video_device->flags.dvi)
1475 					continue;
1476 				break;
1477 			case ACPI_VIDEO_DISPLAY_LCD:
1478 				if (!video_device->flags.lcd)
1479 					continue;
1480 				break;
1481 			}
1482 		} else if (video_device->device_id != device_id) {
1483 			continue;
1484 		}
1485 
1486 		status = acpi_video_device_EDID(video_device, &buffer, length);
1487 
1488 		if (ACPI_FAILURE(status) || !buffer ||
1489 		    buffer->type != ACPI_TYPE_BUFFER) {
1490 			length = 128;
1491 			status = acpi_video_device_EDID(video_device, &buffer,
1492 							length);
1493 			if (ACPI_FAILURE(status) || !buffer ||
1494 			    buffer->type != ACPI_TYPE_BUFFER) {
1495 				continue;
1496 			}
1497 		}
1498 
1499 		*edid = buffer->buffer.pointer;
1500 		return length;
1501 	}
1502 
1503 	return -ENODEV;
1504 }
1505 EXPORT_SYMBOL(acpi_video_get_edid);
1506 
1507 static int
1508 acpi_video_bus_get_devices(struct acpi_video_bus *video,
1509 			   struct acpi_device *device)
1510 {
1511 	/*
1512 	 * There are systems where video module known to work fine regardless
1513 	 * of broken _DOD and ignoring returned value here doesn't cause
1514 	 * any issues later.
1515 	 */
1516 	acpi_video_device_enumerate(video);
1517 
1518 	return acpi_dev_for_each_child(device, acpi_video_bus_get_one_device, video);
1519 }
1520 
1521 /* acpi_video interface */
1522 
1523 /*
1524  * Win8 requires setting bit2 of _DOS to let firmware know it shouldn't
1525  * perform any automatic brightness change on receiving a notification.
1526  */
1527 static int acpi_video_bus_start_devices(struct acpi_video_bus *video)
1528 {
1529 	return acpi_video_bus_DOS(video, 0,
1530 				  acpi_osi_is_win8() ? 1 : 0);
1531 }
1532 
1533 static int acpi_video_bus_stop_devices(struct acpi_video_bus *video)
1534 {
1535 	return acpi_video_bus_DOS(video, 0,
1536 				  acpi_osi_is_win8() ? 0 : 1);
1537 }
1538 
1539 static void acpi_video_bus_notify(struct acpi_device *device, u32 event)
1540 {
1541 	struct acpi_video_bus *video = acpi_driver_data(device);
1542 	struct input_dev *input;
1543 	int keycode = 0;
1544 
1545 	if (!video || !video->input)
1546 		return;
1547 
1548 	input = video->input;
1549 
1550 	switch (event) {
1551 	case ACPI_VIDEO_NOTIFY_SWITCH:	/* User requested a switch,
1552 					 * most likely via hotkey. */
1553 		keycode = KEY_SWITCHVIDEOMODE;
1554 		break;
1555 
1556 	case ACPI_VIDEO_NOTIFY_PROBE:	/* User plugged in or removed a video
1557 					 * connector. */
1558 		acpi_video_device_enumerate(video);
1559 		acpi_video_device_rebind(video);
1560 		keycode = KEY_SWITCHVIDEOMODE;
1561 		break;
1562 
1563 	case ACPI_VIDEO_NOTIFY_CYCLE:	/* Cycle Display output hotkey pressed. */
1564 		keycode = KEY_SWITCHVIDEOMODE;
1565 		break;
1566 	case ACPI_VIDEO_NOTIFY_NEXT_OUTPUT:	/* Next Display output hotkey pressed. */
1567 		keycode = KEY_VIDEO_NEXT;
1568 		break;
1569 	case ACPI_VIDEO_NOTIFY_PREV_OUTPUT:	/* previous Display output hotkey pressed. */
1570 		keycode = KEY_VIDEO_PREV;
1571 		break;
1572 
1573 	default:
1574 		acpi_handle_debug(device->handle, "Unsupported event [0x%x]\n",
1575 				  event);
1576 		break;
1577 	}
1578 
1579 	if (acpi_notifier_call_chain(device, event, 0))
1580 		/* Something vetoed the keypress. */
1581 		keycode = 0;
1582 
1583 	if (keycode && (report_key_events & REPORT_OUTPUT_KEY_EVENTS)) {
1584 		input_report_key(input, keycode, 1);
1585 		input_sync(input);
1586 		input_report_key(input, keycode, 0);
1587 		input_sync(input);
1588 	}
1589 }
1590 
1591 static void brightness_switch_event(struct acpi_video_device *video_device,
1592 				    u32 event)
1593 {
1594 	if (!brightness_switch_enabled)
1595 		return;
1596 
1597 	video_device->switch_brightness_event = event;
1598 	schedule_delayed_work(&video_device->switch_brightness_work, HZ / 10);
1599 }
1600 
1601 static void acpi_video_device_notify(acpi_handle handle, u32 event, void *data)
1602 {
1603 	struct acpi_video_device *video_device = data;
1604 	struct acpi_device *device = NULL;
1605 	struct acpi_video_bus *bus;
1606 	struct input_dev *input;
1607 	int keycode = 0;
1608 
1609 	if (!video_device)
1610 		return;
1611 
1612 	device = video_device->dev;
1613 	bus = video_device->video;
1614 	input = bus->input;
1615 
1616 	if (hw_changes_brightness > 0) {
1617 		if (video_device->backlight)
1618 			backlight_force_update(video_device->backlight,
1619 					       BACKLIGHT_UPDATE_HOTKEY);
1620 		acpi_notifier_call_chain(device, event, 0);
1621 		return;
1622 	}
1623 
1624 	switch (event) {
1625 	case ACPI_VIDEO_NOTIFY_CYCLE_BRIGHTNESS:	/* Cycle brightness */
1626 		brightness_switch_event(video_device, event);
1627 		keycode = KEY_BRIGHTNESS_CYCLE;
1628 		break;
1629 	case ACPI_VIDEO_NOTIFY_INC_BRIGHTNESS:	/* Increase brightness */
1630 		brightness_switch_event(video_device, event);
1631 		keycode = KEY_BRIGHTNESSUP;
1632 		break;
1633 	case ACPI_VIDEO_NOTIFY_DEC_BRIGHTNESS:	/* Decrease brightness */
1634 		brightness_switch_event(video_device, event);
1635 		keycode = KEY_BRIGHTNESSDOWN;
1636 		break;
1637 	case ACPI_VIDEO_NOTIFY_ZERO_BRIGHTNESS:	/* zero brightness */
1638 		brightness_switch_event(video_device, event);
1639 		keycode = KEY_BRIGHTNESS_ZERO;
1640 		break;
1641 	case ACPI_VIDEO_NOTIFY_DISPLAY_OFF:	/* display device off */
1642 		brightness_switch_event(video_device, event);
1643 		keycode = KEY_DISPLAY_OFF;
1644 		break;
1645 	default:
1646 		acpi_handle_debug(handle, "Unsupported event [0x%x]\n", event);
1647 		break;
1648 	}
1649 
1650 	if (keycode)
1651 		may_report_brightness_keys = true;
1652 
1653 	acpi_notifier_call_chain(device, event, 0);
1654 
1655 	if (keycode && (report_key_events & REPORT_BRIGHTNESS_KEY_EVENTS)) {
1656 		input_report_key(input, keycode, 1);
1657 		input_sync(input);
1658 		input_report_key(input, keycode, 0);
1659 		input_sync(input);
1660 	}
1661 }
1662 
1663 static int acpi_video_resume(struct notifier_block *nb,
1664 				unsigned long val, void *ign)
1665 {
1666 	struct acpi_video_bus *video;
1667 	struct acpi_video_device *video_device;
1668 	int i;
1669 
1670 	switch (val) {
1671 	case PM_POST_HIBERNATION:
1672 	case PM_POST_SUSPEND:
1673 	case PM_POST_RESTORE:
1674 		video = container_of(nb, struct acpi_video_bus, pm_nb);
1675 
1676 		dev_info(&video->device->dev, "Restoring backlight state\n");
1677 
1678 		for (i = 0; i < video->attached_count; i++) {
1679 			video_device = video->attached_array[i].bind_info;
1680 			if (video_device && video_device->brightness)
1681 				acpi_video_device_lcd_set_level(video_device,
1682 						video_device->brightness->curr);
1683 		}
1684 
1685 		return NOTIFY_OK;
1686 	}
1687 	return NOTIFY_DONE;
1688 }
1689 
1690 static acpi_status
1691 acpi_video_bus_match(acpi_handle handle, u32 level, void *context,
1692 			void **return_value)
1693 {
1694 	struct acpi_device *device = context;
1695 	struct acpi_device *sibling;
1696 
1697 	if (handle == device->handle)
1698 		return AE_CTRL_TERMINATE;
1699 
1700 	sibling = acpi_fetch_acpi_dev(handle);
1701 	if (!sibling)
1702 		return AE_OK;
1703 
1704 	if (!strcmp(acpi_device_name(sibling), ACPI_VIDEO_BUS_NAME))
1705 			return AE_ALREADY_EXISTS;
1706 
1707 	return AE_OK;
1708 }
1709 
1710 static void acpi_video_dev_register_backlight(struct acpi_video_device *device)
1711 {
1712 	struct backlight_properties props;
1713 	struct pci_dev *pdev;
1714 	acpi_handle acpi_parent;
1715 	struct device *parent = NULL;
1716 	int result;
1717 	static int count;
1718 	char *name;
1719 
1720 	result = acpi_video_init_brightness(device);
1721 	if (result)
1722 		return;
1723 
1724 	name = kasprintf(GFP_KERNEL, "acpi_video%d", count);
1725 	if (!name)
1726 		return;
1727 	count++;
1728 
1729 	acpi_get_parent(device->dev->handle, &acpi_parent);
1730 
1731 	pdev = acpi_get_pci_dev(acpi_parent);
1732 	if (pdev) {
1733 		parent = &pdev->dev;
1734 		pci_dev_put(pdev);
1735 	}
1736 
1737 	memset(&props, 0, sizeof(struct backlight_properties));
1738 	props.type = BACKLIGHT_FIRMWARE;
1739 	props.max_brightness =
1740 		device->brightness->count - ACPI_VIDEO_FIRST_LEVEL - 1;
1741 	device->backlight = backlight_device_register(name,
1742 						      parent,
1743 						      device,
1744 						      &acpi_backlight_ops,
1745 						      &props);
1746 	kfree(name);
1747 	if (IS_ERR(device->backlight)) {
1748 		device->backlight = NULL;
1749 		return;
1750 	}
1751 
1752 	/*
1753 	 * Save current brightness level in case we have to restore it
1754 	 * before acpi_video_device_lcd_set_level() is called next time.
1755 	 */
1756 	device->backlight->props.brightness =
1757 			acpi_video_get_brightness(device->backlight);
1758 
1759 	device->cooling_dev = thermal_cooling_device_register("LCD",
1760 				device->dev, &video_cooling_ops);
1761 	if (IS_ERR(device->cooling_dev)) {
1762 		/*
1763 		 * Set cooling_dev to NULL so we don't crash trying to free it.
1764 		 * Also, why the hell we are returning early and not attempt to
1765 		 * register video output if cooling device registration failed?
1766 		 * -- dtor
1767 		 */
1768 		device->cooling_dev = NULL;
1769 		return;
1770 	}
1771 
1772 	dev_info(&device->dev->dev, "registered as cooling_device%d\n",
1773 		 device->cooling_dev->id);
1774 	result = sysfs_create_link(&device->dev->dev.kobj,
1775 			&device->cooling_dev->device.kobj,
1776 			"thermal_cooling");
1777 	if (result)
1778 		pr_info("sysfs link creation failed\n");
1779 
1780 	result = sysfs_create_link(&device->cooling_dev->device.kobj,
1781 			&device->dev->dev.kobj, "device");
1782 	if (result)
1783 		pr_info("Reverse sysfs link creation failed\n");
1784 }
1785 
1786 static void acpi_video_run_bcl_for_osi(struct acpi_video_bus *video)
1787 {
1788 	struct acpi_video_device *dev;
1789 	union acpi_object *levels;
1790 
1791 	mutex_lock(&video->device_list_lock);
1792 	list_for_each_entry(dev, &video->video_device_list, entry) {
1793 		if (!acpi_video_device_lcd_query_levels(dev->dev->handle, &levels))
1794 			kfree(levels);
1795 	}
1796 	mutex_unlock(&video->device_list_lock);
1797 }
1798 
1799 static bool acpi_video_should_register_backlight(struct acpi_video_device *dev)
1800 {
1801 	/*
1802 	 * Do not create backlight device for video output
1803 	 * device that is not in the enumerated list.
1804 	 */
1805 	if (!acpi_video_device_in_dod(dev)) {
1806 		dev_dbg(&dev->dev->dev, "not in _DOD list, ignore\n");
1807 		return false;
1808 	}
1809 
1810 	if (only_lcd)
1811 		return dev->flags.lcd;
1812 	return true;
1813 }
1814 
1815 static int acpi_video_bus_register_backlight(struct acpi_video_bus *video)
1816 {
1817 	struct acpi_video_device *dev;
1818 
1819 	if (video->backlight_registered)
1820 		return 0;
1821 
1822 	if (acpi_video_get_backlight_type() != acpi_backlight_video)
1823 		return 0;
1824 
1825 	mutex_lock(&video->device_list_lock);
1826 	list_for_each_entry(dev, &video->video_device_list, entry) {
1827 		if (acpi_video_should_register_backlight(dev))
1828 			acpi_video_dev_register_backlight(dev);
1829 	}
1830 	mutex_unlock(&video->device_list_lock);
1831 
1832 	video->backlight_registered = true;
1833 
1834 	video->pm_nb.notifier_call = acpi_video_resume;
1835 	video->pm_nb.priority = 0;
1836 	return register_pm_notifier(&video->pm_nb);
1837 }
1838 
1839 static void acpi_video_dev_unregister_backlight(struct acpi_video_device *device)
1840 {
1841 	if (device->backlight) {
1842 		backlight_device_unregister(device->backlight);
1843 		device->backlight = NULL;
1844 	}
1845 	if (device->brightness) {
1846 		kfree(device->brightness->levels);
1847 		kfree(device->brightness);
1848 		device->brightness = NULL;
1849 	}
1850 	if (device->cooling_dev) {
1851 		sysfs_remove_link(&device->dev->dev.kobj, "thermal_cooling");
1852 		sysfs_remove_link(&device->cooling_dev->device.kobj, "device");
1853 		thermal_cooling_device_unregister(device->cooling_dev);
1854 		device->cooling_dev = NULL;
1855 	}
1856 }
1857 
1858 static int acpi_video_bus_unregister_backlight(struct acpi_video_bus *video)
1859 {
1860 	struct acpi_video_device *dev;
1861 	int error;
1862 
1863 	if (!video->backlight_registered)
1864 		return 0;
1865 
1866 	error = unregister_pm_notifier(&video->pm_nb);
1867 
1868 	mutex_lock(&video->device_list_lock);
1869 	list_for_each_entry(dev, &video->video_device_list, entry)
1870 		acpi_video_dev_unregister_backlight(dev);
1871 	mutex_unlock(&video->device_list_lock);
1872 
1873 	video->backlight_registered = false;
1874 
1875 	return error;
1876 }
1877 
1878 static void acpi_video_dev_add_notify_handler(struct acpi_video_device *device)
1879 {
1880 	acpi_status status;
1881 	struct acpi_device *adev = device->dev;
1882 
1883 	status = acpi_install_notify_handler(adev->handle, ACPI_DEVICE_NOTIFY,
1884 					     acpi_video_device_notify, device);
1885 	if (ACPI_FAILURE(status))
1886 		dev_err(&adev->dev, "Error installing notify handler\n");
1887 	else
1888 		device->flags.notify = 1;
1889 }
1890 
1891 static int acpi_video_bus_add_notify_handler(struct acpi_video_bus *video)
1892 {
1893 	struct input_dev *input;
1894 	struct acpi_video_device *dev;
1895 	int error;
1896 
1897 	video->input = input = input_allocate_device();
1898 	if (!input) {
1899 		error = -ENOMEM;
1900 		goto out;
1901 	}
1902 
1903 	error = acpi_video_bus_start_devices(video);
1904 	if (error)
1905 		goto err_free_input;
1906 
1907 	snprintf(video->phys, sizeof(video->phys),
1908 			"%s/video/input0", acpi_device_hid(video->device));
1909 
1910 	input->name = acpi_device_name(video->device);
1911 	input->phys = video->phys;
1912 	input->id.bustype = BUS_HOST;
1913 	input->id.product = 0x06;
1914 	input->dev.parent = &video->device->dev;
1915 	input->evbit[0] = BIT(EV_KEY);
1916 	set_bit(KEY_SWITCHVIDEOMODE, input->keybit);
1917 	set_bit(KEY_VIDEO_NEXT, input->keybit);
1918 	set_bit(KEY_VIDEO_PREV, input->keybit);
1919 	set_bit(KEY_BRIGHTNESS_CYCLE, input->keybit);
1920 	set_bit(KEY_BRIGHTNESSUP, input->keybit);
1921 	set_bit(KEY_BRIGHTNESSDOWN, input->keybit);
1922 	set_bit(KEY_BRIGHTNESS_ZERO, input->keybit);
1923 	set_bit(KEY_DISPLAY_OFF, input->keybit);
1924 
1925 	error = input_register_device(input);
1926 	if (error)
1927 		goto err_stop_dev;
1928 
1929 	mutex_lock(&video->device_list_lock);
1930 	list_for_each_entry(dev, &video->video_device_list, entry)
1931 		acpi_video_dev_add_notify_handler(dev);
1932 	mutex_unlock(&video->device_list_lock);
1933 
1934 	return 0;
1935 
1936 err_stop_dev:
1937 	acpi_video_bus_stop_devices(video);
1938 err_free_input:
1939 	input_free_device(input);
1940 	video->input = NULL;
1941 out:
1942 	return error;
1943 }
1944 
1945 static void acpi_video_dev_remove_notify_handler(struct acpi_video_device *dev)
1946 {
1947 	if (dev->flags.notify) {
1948 		acpi_remove_notify_handler(dev->dev->handle, ACPI_DEVICE_NOTIFY,
1949 					   acpi_video_device_notify);
1950 		dev->flags.notify = 0;
1951 	}
1952 }
1953 
1954 static void acpi_video_bus_remove_notify_handler(struct acpi_video_bus *video)
1955 {
1956 	struct acpi_video_device *dev;
1957 
1958 	mutex_lock(&video->device_list_lock);
1959 	list_for_each_entry(dev, &video->video_device_list, entry)
1960 		acpi_video_dev_remove_notify_handler(dev);
1961 	mutex_unlock(&video->device_list_lock);
1962 
1963 	acpi_video_bus_stop_devices(video);
1964 	input_unregister_device(video->input);
1965 	video->input = NULL;
1966 }
1967 
1968 static int acpi_video_bus_put_devices(struct acpi_video_bus *video)
1969 {
1970 	struct acpi_video_device *dev, *next;
1971 
1972 	mutex_lock(&video->device_list_lock);
1973 	list_for_each_entry_safe(dev, next, &video->video_device_list, entry) {
1974 		list_del(&dev->entry);
1975 		kfree(dev);
1976 	}
1977 	mutex_unlock(&video->device_list_lock);
1978 
1979 	return 0;
1980 }
1981 
1982 static int instance;
1983 
1984 static int acpi_video_bus_add(struct acpi_device *device)
1985 {
1986 	struct acpi_video_bus *video;
1987 	bool auto_detect;
1988 	int error;
1989 	acpi_status status;
1990 
1991 	status = acpi_walk_namespace(ACPI_TYPE_DEVICE,
1992 				acpi_dev_parent(device)->handle, 1,
1993 				acpi_video_bus_match, NULL,
1994 				device, NULL);
1995 	if (status == AE_ALREADY_EXISTS) {
1996 		pr_info(FW_BUG
1997 			"Duplicate ACPI video bus devices for the"
1998 			" same VGA controller, please try module "
1999 			"parameter \"video.allow_duplicates=1\""
2000 			"if the current driver doesn't work.\n");
2001 		if (!allow_duplicates)
2002 			return -ENODEV;
2003 	}
2004 
2005 	video = kzalloc(sizeof(struct acpi_video_bus), GFP_KERNEL);
2006 	if (!video)
2007 		return -ENOMEM;
2008 
2009 	/* a hack to fix the duplicate name "VID" problem on T61 */
2010 	if (!strcmp(device->pnp.bus_id, "VID")) {
2011 		if (instance)
2012 			device->pnp.bus_id[3] = '0' + instance;
2013 		instance++;
2014 	}
2015 	/* a hack to fix the duplicate name "VGA" problem on Pa 3553 */
2016 	if (!strcmp(device->pnp.bus_id, "VGA")) {
2017 		if (instance)
2018 			device->pnp.bus_id[3] = '0' + instance;
2019 		instance++;
2020 	}
2021 
2022 	video->device = device;
2023 	strcpy(acpi_device_name(device), ACPI_VIDEO_BUS_NAME);
2024 	strcpy(acpi_device_class(device), ACPI_VIDEO_CLASS);
2025 	device->driver_data = video;
2026 
2027 	acpi_video_bus_find_cap(video);
2028 	error = acpi_video_bus_check(video);
2029 	if (error)
2030 		goto err_free_video;
2031 
2032 	mutex_init(&video->device_list_lock);
2033 	INIT_LIST_HEAD(&video->video_device_list);
2034 
2035 	error = acpi_video_bus_get_devices(video, device);
2036 	if (error)
2037 		goto err_put_video;
2038 
2039 	pr_info("%s [%s] (multi-head: %s  rom: %s  post: %s)\n",
2040 	       ACPI_VIDEO_DEVICE_NAME, acpi_device_bid(device),
2041 	       video->flags.multihead ? "yes" : "no",
2042 	       video->flags.rom ? "yes" : "no",
2043 	       video->flags.post ? "yes" : "no");
2044 	mutex_lock(&video_list_lock);
2045 	list_add_tail(&video->entry, &video_bus_head);
2046 	mutex_unlock(&video_list_lock);
2047 
2048 	/*
2049 	 * If backlight-type auto-detection is used then a native backlight may
2050 	 * show up later and this may change the result from video to native.
2051 	 * Therefor normally the userspace visible /sys/class/backlight device
2052 	 * gets registered separately by the GPU driver calling
2053 	 * acpi_video_register_backlight() when an internal panel is detected.
2054 	 * Register the backlight now when not using auto-detection, so that
2055 	 * when the kernel cmdline or DMI-quirks are used the backlight will
2056 	 * get registered even if acpi_video_register_backlight() is not called.
2057 	 */
2058 	acpi_video_run_bcl_for_osi(video);
2059 	if (__acpi_video_get_backlight_type(false, &auto_detect) == acpi_backlight_video &&
2060 	    !auto_detect)
2061 		acpi_video_bus_register_backlight(video);
2062 
2063 	acpi_video_bus_add_notify_handler(video);
2064 
2065 	return 0;
2066 
2067 err_put_video:
2068 	acpi_video_bus_put_devices(video);
2069 	kfree(video->attached_array);
2070 err_free_video:
2071 	kfree(video);
2072 	device->driver_data = NULL;
2073 
2074 	return error;
2075 }
2076 
2077 static void acpi_video_bus_remove(struct acpi_device *device)
2078 {
2079 	struct acpi_video_bus *video = NULL;
2080 
2081 
2082 	if (!device || !acpi_driver_data(device))
2083 		return;
2084 
2085 	video = acpi_driver_data(device);
2086 
2087 	mutex_lock(&video_list_lock);
2088 	list_del(&video->entry);
2089 	mutex_unlock(&video_list_lock);
2090 
2091 	acpi_video_bus_remove_notify_handler(video);
2092 	acpi_video_bus_unregister_backlight(video);
2093 	acpi_video_bus_put_devices(video);
2094 
2095 	kfree(video->attached_array);
2096 	kfree(video);
2097 }
2098 
2099 static void acpi_video_bus_register_backlight_work(struct work_struct *ignored)
2100 {
2101 	acpi_video_register_backlight();
2102 }
2103 
2104 static int __init is_i740(struct pci_dev *dev)
2105 {
2106 	if (dev->device == 0x00D1)
2107 		return 1;
2108 	if (dev->device == 0x7000)
2109 		return 1;
2110 	return 0;
2111 }
2112 
2113 static int __init intel_opregion_present(void)
2114 {
2115 	int opregion = 0;
2116 	struct pci_dev *dev = NULL;
2117 	u32 address;
2118 
2119 	for_each_pci_dev(dev) {
2120 		if ((dev->class >> 8) != PCI_CLASS_DISPLAY_VGA)
2121 			continue;
2122 		if (dev->vendor != PCI_VENDOR_ID_INTEL)
2123 			continue;
2124 		/* We don't want to poke around undefined i740 registers */
2125 		if (is_i740(dev))
2126 			continue;
2127 		pci_read_config_dword(dev, 0xfc, &address);
2128 		if (!address)
2129 			continue;
2130 		opregion = 1;
2131 	}
2132 	return opregion;
2133 }
2134 
2135 /* Check if the chassis-type indicates there is no builtin LCD panel */
2136 static bool dmi_is_desktop(void)
2137 {
2138 	const char *chassis_type;
2139 	unsigned long type;
2140 
2141 	chassis_type = dmi_get_system_info(DMI_CHASSIS_TYPE);
2142 	if (!chassis_type)
2143 		return false;
2144 
2145 	if (kstrtoul(chassis_type, 10, &type) != 0)
2146 		return false;
2147 
2148 	switch (type) {
2149 	case 0x03: /* Desktop */
2150 	case 0x04: /* Low Profile Desktop */
2151 	case 0x05: /* Pizza Box */
2152 	case 0x06: /* Mini Tower */
2153 	case 0x07: /* Tower */
2154 	case 0x10: /* Lunch Box */
2155 	case 0x11: /* Main Server Chassis */
2156 		return true;
2157 	}
2158 
2159 	return false;
2160 }
2161 
2162 /*
2163  * We're seeing a lot of bogus backlight interfaces on newer machines
2164  * without a LCD such as desktops, servers and HDMI sticks. Checking the
2165  * lcd flag fixes this, enable this by default on any machines which are:
2166  * 1.  Win8 ready (where we also prefer the native backlight driver, so
2167  *     normally the acpi_video code should not register there anyways); *and*
2168  * 2.1 Report a desktop/server DMI chassis-type, or
2169  * 2.2 Are an ACPI-reduced-hardware platform (and thus won't use the EC for
2170        backlight control)
2171  */
2172 static bool should_check_lcd_flag(void)
2173 {
2174 	if (!acpi_osi_is_win8())
2175 		return false;
2176 
2177 	if (dmi_is_desktop())
2178 		return true;
2179 
2180 	if (acpi_reduced_hardware())
2181 		return true;
2182 
2183 	return false;
2184 }
2185 
2186 /*
2187  * At least one graphics driver has reported that no LCD is connected
2188  * via the native interface. cancel the registration for fallback acpi_video0.
2189  * If another driver still deems this necessary, it can explicitly register it.
2190  */
2191 void acpi_video_report_nolcd(void)
2192 {
2193 	cancel_delayed_work(&video_bus_register_backlight_work);
2194 }
2195 EXPORT_SYMBOL(acpi_video_report_nolcd);
2196 
2197 int acpi_video_register(void)
2198 {
2199 	int ret = 0;
2200 
2201 	mutex_lock(&register_count_mutex);
2202 	if (register_count) {
2203 		/*
2204 		 * if the function of acpi_video_register is already called,
2205 		 * don't register the acpi_video_bus again and return no error.
2206 		 */
2207 		goto leave;
2208 	}
2209 
2210 	if (only_lcd == -1)
2211 		only_lcd = should_check_lcd_flag();
2212 
2213 	dmi_check_system(video_dmi_table);
2214 
2215 	ret = acpi_bus_register_driver(&acpi_video_bus);
2216 	if (ret)
2217 		goto leave;
2218 
2219 	/*
2220 	 * When the acpi_video_bus is loaded successfully, increase
2221 	 * the counter reference.
2222 	 */
2223 	register_count = 1;
2224 
2225 	/*
2226 	 * acpi_video_bus_add() skips registering the userspace visible
2227 	 * backlight_device. The intend is for this to be registered by the
2228 	 * drm/kms driver calling acpi_video_register_backlight() *after* it is
2229 	 * done setting up its own native backlight device. The delayed work
2230 	 * ensures that acpi_video_register_backlight() always gets called
2231 	 * eventually, in case there is no drm/kms driver or it is disabled.
2232 	 */
2233 	if (register_backlight_delay)
2234 		schedule_delayed_work(&video_bus_register_backlight_work,
2235 				      register_backlight_delay * HZ);
2236 
2237 leave:
2238 	mutex_unlock(&register_count_mutex);
2239 	return ret;
2240 }
2241 EXPORT_SYMBOL(acpi_video_register);
2242 
2243 void acpi_video_unregister(void)
2244 {
2245 	mutex_lock(&register_count_mutex);
2246 	if (register_count) {
2247 		cancel_delayed_work_sync(&video_bus_register_backlight_work);
2248 		acpi_bus_unregister_driver(&acpi_video_bus);
2249 		register_count = 0;
2250 		may_report_brightness_keys = false;
2251 	}
2252 	mutex_unlock(&register_count_mutex);
2253 }
2254 EXPORT_SYMBOL(acpi_video_unregister);
2255 
2256 void acpi_video_register_backlight(void)
2257 {
2258 	struct acpi_video_bus *video;
2259 
2260 	mutex_lock(&video_list_lock);
2261 	list_for_each_entry(video, &video_bus_head, entry)
2262 		acpi_video_bus_register_backlight(video);
2263 	mutex_unlock(&video_list_lock);
2264 }
2265 EXPORT_SYMBOL(acpi_video_register_backlight);
2266 
2267 bool acpi_video_handles_brightness_key_presses(void)
2268 {
2269 	return may_report_brightness_keys &&
2270 	       (report_key_events & REPORT_BRIGHTNESS_KEY_EVENTS);
2271 }
2272 EXPORT_SYMBOL(acpi_video_handles_brightness_key_presses);
2273 
2274 /*
2275  * This is kind of nasty. Hardware using Intel chipsets may require
2276  * the video opregion code to be run first in order to initialise
2277  * state before any ACPI video calls are made. To handle this we defer
2278  * registration of the video class until the opregion code has run.
2279  */
2280 
2281 static int __init acpi_video_init(void)
2282 {
2283 	/*
2284 	 * Let the module load even if ACPI is disabled (e.g. due to
2285 	 * a broken BIOS) so that i915.ko can still be loaded on such
2286 	 * old systems without an AcpiOpRegion.
2287 	 *
2288 	 * acpi_video_register() will report -ENODEV later as well due
2289 	 * to acpi_disabled when i915.ko tries to register itself afterwards.
2290 	 */
2291 	if (acpi_disabled)
2292 		return 0;
2293 
2294 	if (intel_opregion_present())
2295 		return 0;
2296 
2297 	return acpi_video_register();
2298 }
2299 
2300 static void __exit acpi_video_exit(void)
2301 {
2302 	acpi_video_unregister();
2303 }
2304 
2305 module_init(acpi_video_init);
2306 module_exit(acpi_video_exit);
2307