xref: /openbmc/linux/drivers/acpi/acpi_video.c (revision 9cfc5c90)
1 /*
2  *  video.c - ACPI Video Driver
3  *
4  *  Copyright (C) 2004 Luming Yu <luming.yu@intel.com>
5  *  Copyright (C) 2004 Bruno Ducrot <ducrot@poupinou.org>
6  *  Copyright (C) 2006 Thomas Tuttle <linux-kernel@ttuttle.net>
7  *
8  * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
9  *
10  *  This program is free software; you can redistribute it and/or modify
11  *  it under the terms of the GNU General Public License as published by
12  *  the Free Software Foundation; either version 2 of the License, or (at
13  *  your option) any later version.
14  *
15  *  This program is distributed in the hope that it will be useful, but
16  *  WITHOUT ANY WARRANTY; without even the implied warranty of
17  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
18  *  General Public License for more details.
19  *
20  * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
21  */
22 
23 #include <linux/kernel.h>
24 #include <linux/module.h>
25 #include <linux/init.h>
26 #include <linux/types.h>
27 #include <linux/list.h>
28 #include <linux/mutex.h>
29 #include <linux/input.h>
30 #include <linux/backlight.h>
31 #include <linux/thermal.h>
32 #include <linux/sort.h>
33 #include <linux/pci.h>
34 #include <linux/pci_ids.h>
35 #include <linux/slab.h>
36 #include <linux/dmi.h>
37 #include <linux/suspend.h>
38 #include <linux/acpi.h>
39 #include <acpi/video.h>
40 #include <asm/uaccess.h>
41 
42 #define PREFIX "ACPI: "
43 
44 #define ACPI_VIDEO_BUS_NAME		"Video Bus"
45 #define ACPI_VIDEO_DEVICE_NAME		"Video Device"
46 #define ACPI_VIDEO_NOTIFY_SWITCH	0x80
47 #define ACPI_VIDEO_NOTIFY_PROBE		0x81
48 #define ACPI_VIDEO_NOTIFY_CYCLE		0x82
49 #define ACPI_VIDEO_NOTIFY_NEXT_OUTPUT	0x83
50 #define ACPI_VIDEO_NOTIFY_PREV_OUTPUT	0x84
51 
52 #define ACPI_VIDEO_NOTIFY_CYCLE_BRIGHTNESS	0x85
53 #define	ACPI_VIDEO_NOTIFY_INC_BRIGHTNESS	0x86
54 #define ACPI_VIDEO_NOTIFY_DEC_BRIGHTNESS	0x87
55 #define ACPI_VIDEO_NOTIFY_ZERO_BRIGHTNESS	0x88
56 #define ACPI_VIDEO_NOTIFY_DISPLAY_OFF		0x89
57 
58 #define MAX_NAME_LEN	20
59 
60 #define _COMPONENT		ACPI_VIDEO_COMPONENT
61 ACPI_MODULE_NAME("video");
62 
63 MODULE_AUTHOR("Bruno Ducrot");
64 MODULE_DESCRIPTION("ACPI Video Driver");
65 MODULE_LICENSE("GPL");
66 
67 static bool brightness_switch_enabled = 1;
68 module_param(brightness_switch_enabled, bool, 0644);
69 
70 /*
71  * By default, we don't allow duplicate ACPI video bus devices
72  * under the same VGA controller
73  */
74 static bool allow_duplicates;
75 module_param(allow_duplicates, bool, 0644);
76 
77 static int disable_backlight_sysfs_if = -1;
78 module_param(disable_backlight_sysfs_if, int, 0444);
79 
80 static bool device_id_scheme = false;
81 module_param(device_id_scheme, bool, 0444);
82 
83 static bool only_lcd = false;
84 module_param(only_lcd, bool, 0444);
85 
86 static int register_count;
87 static DEFINE_MUTEX(register_count_mutex);
88 static struct mutex video_list_lock;
89 static struct list_head video_bus_head;
90 static int acpi_video_bus_add(struct acpi_device *device);
91 static int acpi_video_bus_remove(struct acpi_device *device);
92 static void acpi_video_bus_notify(struct acpi_device *device, u32 event);
93 void acpi_video_detect_exit(void);
94 
95 static const struct acpi_device_id video_device_ids[] = {
96 	{ACPI_VIDEO_HID, 0},
97 	{"", 0},
98 };
99 MODULE_DEVICE_TABLE(acpi, video_device_ids);
100 
101 static struct acpi_driver acpi_video_bus = {
102 	.name = "video",
103 	.class = ACPI_VIDEO_CLASS,
104 	.ids = video_device_ids,
105 	.ops = {
106 		.add = acpi_video_bus_add,
107 		.remove = acpi_video_bus_remove,
108 		.notify = acpi_video_bus_notify,
109 		},
110 };
111 
112 struct acpi_video_bus_flags {
113 	u8 multihead:1;		/* can switch video heads */
114 	u8 rom:1;		/* can retrieve a video rom */
115 	u8 post:1;		/* can configure the head to */
116 	u8 reserved:5;
117 };
118 
119 struct acpi_video_bus_cap {
120 	u8 _DOS:1;		/* Enable/Disable output switching */
121 	u8 _DOD:1;		/* Enumerate all devices attached to display adapter */
122 	u8 _ROM:1;		/* Get ROM Data */
123 	u8 _GPD:1;		/* Get POST Device */
124 	u8 _SPD:1;		/* Set POST Device */
125 	u8 _VPO:1;		/* Video POST Options */
126 	u8 reserved:2;
127 };
128 
129 struct acpi_video_device_attrib {
130 	u32 display_index:4;	/* A zero-based instance of the Display */
131 	u32 display_port_attachment:4;	/* This field differentiates the display type */
132 	u32 display_type:4;	/* Describe the specific type in use */
133 	u32 vendor_specific:4;	/* Chipset Vendor Specific */
134 	u32 bios_can_detect:1;	/* BIOS can detect the device */
135 	u32 depend_on_vga:1;	/* Non-VGA output device whose power is related to
136 				   the VGA device. */
137 	u32 pipe_id:3;		/* For VGA multiple-head devices. */
138 	u32 reserved:10;	/* Must be 0 */
139 	u32 device_id_scheme:1;	/* Device ID Scheme */
140 };
141 
142 struct acpi_video_enumerated_device {
143 	union {
144 		u32 int_val;
145 		struct acpi_video_device_attrib attrib;
146 	} value;
147 	struct acpi_video_device *bind_info;
148 };
149 
150 struct acpi_video_bus {
151 	struct acpi_device *device;
152 	bool backlight_registered;
153 	u8 dos_setting;
154 	struct acpi_video_enumerated_device *attached_array;
155 	u8 attached_count;
156 	u8 child_count;
157 	struct acpi_video_bus_cap cap;
158 	struct acpi_video_bus_flags flags;
159 	struct list_head video_device_list;
160 	struct mutex device_list_lock;	/* protects video_device_list */
161 	struct list_head entry;
162 	struct input_dev *input;
163 	char phys[32];	/* for input device */
164 	struct notifier_block pm_nb;
165 };
166 
167 struct acpi_video_device_flags {
168 	u8 crt:1;
169 	u8 lcd:1;
170 	u8 tvout:1;
171 	u8 dvi:1;
172 	u8 bios:1;
173 	u8 unknown:1;
174 	u8 notify:1;
175 	u8 reserved:1;
176 };
177 
178 struct acpi_video_device_cap {
179 	u8 _ADR:1;		/* Return the unique ID */
180 	u8 _BCL:1;		/* Query list of brightness control levels supported */
181 	u8 _BCM:1;		/* Set the brightness level */
182 	u8 _BQC:1;		/* Get current brightness level */
183 	u8 _BCQ:1;		/* Some buggy BIOS uses _BCQ instead of _BQC */
184 	u8 _DDC:1;		/* Return the EDID for this device */
185 };
186 
187 struct acpi_video_brightness_flags {
188 	u8 _BCL_no_ac_battery_levels:1;	/* no AC/Battery levels in _BCL */
189 	u8 _BCL_reversed:1;		/* _BCL package is in a reversed order */
190 	u8 _BQC_use_index:1;		/* _BQC returns an index value */
191 };
192 
193 struct acpi_video_device_brightness {
194 	int curr;
195 	int count;
196 	int *levels;
197 	struct acpi_video_brightness_flags flags;
198 };
199 
200 struct acpi_video_device {
201 	unsigned long device_id;
202 	struct acpi_video_device_flags flags;
203 	struct acpi_video_device_cap cap;
204 	struct list_head entry;
205 	struct delayed_work switch_brightness_work;
206 	int switch_brightness_event;
207 	struct acpi_video_bus *video;
208 	struct acpi_device *dev;
209 	struct acpi_video_device_brightness *brightness;
210 	struct backlight_device *backlight;
211 	struct thermal_cooling_device *cooling_dev;
212 };
213 
214 static const char device_decode[][30] = {
215 	"motherboard VGA device",
216 	"PCI VGA device",
217 	"AGP VGA device",
218 	"UNKNOWN",
219 };
220 
221 static void acpi_video_device_notify(acpi_handle handle, u32 event, void *data);
222 static void acpi_video_device_rebind(struct acpi_video_bus *video);
223 static void acpi_video_device_bind(struct acpi_video_bus *video,
224 				   struct acpi_video_device *device);
225 static int acpi_video_device_enumerate(struct acpi_video_bus *video);
226 static int acpi_video_device_lcd_set_level(struct acpi_video_device *device,
227 			int level);
228 static int acpi_video_device_lcd_get_level_current(
229 			struct acpi_video_device *device,
230 			unsigned long long *level, bool raw);
231 static int acpi_video_get_next_level(struct acpi_video_device *device,
232 				     u32 level_current, u32 event);
233 static void acpi_video_switch_brightness(struct work_struct *work);
234 
235 /* backlight device sysfs support */
236 static int acpi_video_get_brightness(struct backlight_device *bd)
237 {
238 	unsigned long long cur_level;
239 	int i;
240 	struct acpi_video_device *vd = bl_get_data(bd);
241 
242 	if (acpi_video_device_lcd_get_level_current(vd, &cur_level, false))
243 		return -EINVAL;
244 	for (i = 2; i < vd->brightness->count; i++) {
245 		if (vd->brightness->levels[i] == cur_level)
246 			/*
247 			 * The first two entries are special - see page 575
248 			 * of the ACPI spec 3.0
249 			 */
250 			return i - 2;
251 	}
252 	return 0;
253 }
254 
255 static int acpi_video_set_brightness(struct backlight_device *bd)
256 {
257 	int request_level = bd->props.brightness + 2;
258 	struct acpi_video_device *vd = bl_get_data(bd);
259 
260 	cancel_delayed_work(&vd->switch_brightness_work);
261 	return acpi_video_device_lcd_set_level(vd,
262 				vd->brightness->levels[request_level]);
263 }
264 
265 static const struct backlight_ops acpi_backlight_ops = {
266 	.get_brightness = acpi_video_get_brightness,
267 	.update_status  = acpi_video_set_brightness,
268 };
269 
270 /* thermal cooling device callbacks */
271 static int video_get_max_state(struct thermal_cooling_device *cooling_dev, unsigned
272 			       long *state)
273 {
274 	struct acpi_device *device = cooling_dev->devdata;
275 	struct acpi_video_device *video = acpi_driver_data(device);
276 
277 	*state = video->brightness->count - 3;
278 	return 0;
279 }
280 
281 static int video_get_cur_state(struct thermal_cooling_device *cooling_dev, unsigned
282 			       long *state)
283 {
284 	struct acpi_device *device = cooling_dev->devdata;
285 	struct acpi_video_device *video = acpi_driver_data(device);
286 	unsigned long long level;
287 	int offset;
288 
289 	if (acpi_video_device_lcd_get_level_current(video, &level, false))
290 		return -EINVAL;
291 	for (offset = 2; offset < video->brightness->count; offset++)
292 		if (level == video->brightness->levels[offset]) {
293 			*state = video->brightness->count - offset - 1;
294 			return 0;
295 		}
296 
297 	return -EINVAL;
298 }
299 
300 static int
301 video_set_cur_state(struct thermal_cooling_device *cooling_dev, unsigned long state)
302 {
303 	struct acpi_device *device = cooling_dev->devdata;
304 	struct acpi_video_device *video = acpi_driver_data(device);
305 	int level;
306 
307 	if (state >= video->brightness->count - 2)
308 		return -EINVAL;
309 
310 	state = video->brightness->count - state;
311 	level = video->brightness->levels[state - 1];
312 	return acpi_video_device_lcd_set_level(video, level);
313 }
314 
315 static const struct thermal_cooling_device_ops video_cooling_ops = {
316 	.get_max_state = video_get_max_state,
317 	.get_cur_state = video_get_cur_state,
318 	.set_cur_state = video_set_cur_state,
319 };
320 
321 /*
322  * --------------------------------------------------------------------------
323  *                             Video Management
324  * --------------------------------------------------------------------------
325  */
326 
327 static int
328 acpi_video_device_lcd_query_levels(struct acpi_video_device *device,
329 				   union acpi_object **levels)
330 {
331 	int status;
332 	struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
333 	union acpi_object *obj;
334 
335 
336 	*levels = NULL;
337 
338 	status = acpi_evaluate_object(device->dev->handle, "_BCL", NULL, &buffer);
339 	if (!ACPI_SUCCESS(status))
340 		return status;
341 	obj = (union acpi_object *)buffer.pointer;
342 	if (!obj || (obj->type != ACPI_TYPE_PACKAGE)) {
343 		printk(KERN_ERR PREFIX "Invalid _BCL data\n");
344 		status = -EFAULT;
345 		goto err;
346 	}
347 
348 	*levels = obj;
349 
350 	return 0;
351 
352 err:
353 	kfree(buffer.pointer);
354 
355 	return status;
356 }
357 
358 static int
359 acpi_video_device_lcd_set_level(struct acpi_video_device *device, int level)
360 {
361 	int status;
362 	int state;
363 
364 	status = acpi_execute_simple_method(device->dev->handle,
365 					    "_BCM", level);
366 	if (ACPI_FAILURE(status)) {
367 		ACPI_ERROR((AE_INFO, "Evaluating _BCM failed"));
368 		return -EIO;
369 	}
370 
371 	device->brightness->curr = level;
372 	for (state = 2; state < device->brightness->count; state++)
373 		if (level == device->brightness->levels[state]) {
374 			if (device->backlight)
375 				device->backlight->props.brightness = state - 2;
376 			return 0;
377 		}
378 
379 	ACPI_ERROR((AE_INFO, "Current brightness invalid"));
380 	return -EINVAL;
381 }
382 
383 /*
384  * For some buggy _BQC methods, we need to add a constant value to
385  * the _BQC return value to get the actual current brightness level
386  */
387 
388 static int bqc_offset_aml_bug_workaround;
389 static int video_set_bqc_offset(const struct dmi_system_id *d)
390 {
391 	bqc_offset_aml_bug_workaround = 9;
392 	return 0;
393 }
394 
395 static int video_disable_backlight_sysfs_if(
396 	const struct dmi_system_id *d)
397 {
398 	if (disable_backlight_sysfs_if == -1)
399 		disable_backlight_sysfs_if = 1;
400 	return 0;
401 }
402 
403 static int video_set_device_id_scheme(const struct dmi_system_id *d)
404 {
405 	device_id_scheme = true;
406 	return 0;
407 }
408 
409 static int video_enable_only_lcd(const struct dmi_system_id *d)
410 {
411 	only_lcd = true;
412 	return 0;
413 }
414 
415 static struct dmi_system_id video_dmi_table[] = {
416 	/*
417 	 * Broken _BQC workaround http://bugzilla.kernel.org/show_bug.cgi?id=13121
418 	 */
419 	{
420 	 .callback = video_set_bqc_offset,
421 	 .ident = "Acer Aspire 5720",
422 	 .matches = {
423 		DMI_MATCH(DMI_BOARD_VENDOR, "Acer"),
424 		DMI_MATCH(DMI_PRODUCT_NAME, "Aspire 5720"),
425 		},
426 	},
427 	{
428 	 .callback = video_set_bqc_offset,
429 	 .ident = "Acer Aspire 5710Z",
430 	 .matches = {
431 		DMI_MATCH(DMI_BOARD_VENDOR, "Acer"),
432 		DMI_MATCH(DMI_PRODUCT_NAME, "Aspire 5710Z"),
433 		},
434 	},
435 	{
436 	 .callback = video_set_bqc_offset,
437 	 .ident = "eMachines E510",
438 	 .matches = {
439 		DMI_MATCH(DMI_BOARD_VENDOR, "EMACHINES"),
440 		DMI_MATCH(DMI_PRODUCT_NAME, "eMachines E510"),
441 		},
442 	},
443 	{
444 	 .callback = video_set_bqc_offset,
445 	 .ident = "Acer Aspire 5315",
446 	 .matches = {
447 		DMI_MATCH(DMI_BOARD_VENDOR, "Acer"),
448 		DMI_MATCH(DMI_PRODUCT_NAME, "Aspire 5315"),
449 		},
450 	},
451 	{
452 	 .callback = video_set_bqc_offset,
453 	 .ident = "Acer Aspire 7720",
454 	 .matches = {
455 		DMI_MATCH(DMI_BOARD_VENDOR, "Acer"),
456 		DMI_MATCH(DMI_PRODUCT_NAME, "Aspire 7720"),
457 		},
458 	},
459 
460 	/*
461 	 * Some machines have a broken acpi-video interface for brightness
462 	 * control, but still need an acpi_video_device_lcd_set_level() call
463 	 * on resume to turn the backlight power on.  We Enable backlight
464 	 * control on these systems, but do not register a backlight sysfs
465 	 * as brightness control does not work.
466 	 */
467 	{
468 	 /* https://bugs.freedesktop.org/show_bug.cgi?id=82634 */
469 	 .callback = video_disable_backlight_sysfs_if,
470 	 .ident = "Toshiba Portege R830",
471 	 .matches = {
472 		DMI_MATCH(DMI_SYS_VENDOR, "TOSHIBA"),
473 		DMI_MATCH(DMI_PRODUCT_NAME, "PORTEGE R830"),
474 		},
475 	},
476 	/*
477 	 * Some machine's _DOD IDs don't have bit 31(Device ID Scheme) set
478 	 * but the IDs actually follow the Device ID Scheme.
479 	 */
480 	{
481 	 /* https://bugzilla.kernel.org/show_bug.cgi?id=104121 */
482 	 .callback = video_set_device_id_scheme,
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 have multiple video output devices, but only the one
491 	 * that is the type of LCD can do the backlight control so we should not
492 	 * register backlight interface for other video output devices.
493 	 */
494 	{
495 	 /* https://bugzilla.kernel.org/show_bug.cgi?id=104121 */
496 	 .callback = video_enable_only_lcd,
497 	 .ident = "ESPRIMO Mobile M9410",
498 	 .matches = {
499 		DMI_MATCH(DMI_SYS_VENDOR, "FUJITSU SIEMENS"),
500 		DMI_MATCH(DMI_PRODUCT_NAME, "ESPRIMO Mobile M9410"),
501 		},
502 	},
503 	{}
504 };
505 
506 static unsigned long long
507 acpi_video_bqc_value_to_level(struct acpi_video_device *device,
508 			      unsigned long long bqc_value)
509 {
510 	unsigned long long level;
511 
512 	if (device->brightness->flags._BQC_use_index) {
513 		/*
514 		 * _BQC returns an index that doesn't account for
515 		 * the first 2 items with special meaning, so we need
516 		 * to compensate for that by offsetting ourselves
517 		 */
518 		if (device->brightness->flags._BCL_reversed)
519 			bqc_value = device->brightness->count - 3 - bqc_value;
520 
521 		level = device->brightness->levels[bqc_value + 2];
522 	} else {
523 		level = bqc_value;
524 	}
525 
526 	level += bqc_offset_aml_bug_workaround;
527 
528 	return level;
529 }
530 
531 static int
532 acpi_video_device_lcd_get_level_current(struct acpi_video_device *device,
533 					unsigned long long *level, bool raw)
534 {
535 	acpi_status status = AE_OK;
536 	int i;
537 
538 	if (device->cap._BQC || device->cap._BCQ) {
539 		char *buf = device->cap._BQC ? "_BQC" : "_BCQ";
540 
541 		status = acpi_evaluate_integer(device->dev->handle, buf,
542 						NULL, level);
543 		if (ACPI_SUCCESS(status)) {
544 			if (raw) {
545 				/*
546 				 * Caller has indicated he wants the raw
547 				 * value returned by _BQC, so don't furtherly
548 				 * mess with the value.
549 				 */
550 				return 0;
551 			}
552 
553 			*level = acpi_video_bqc_value_to_level(device, *level);
554 
555 			for (i = 2; i < device->brightness->count; i++)
556 				if (device->brightness->levels[i] == *level) {
557 					device->brightness->curr = *level;
558 					return 0;
559 				}
560 			/*
561 			 * BQC returned an invalid level.
562 			 * Stop using it.
563 			 */
564 			ACPI_WARNING((AE_INFO,
565 				      "%s returned an invalid level",
566 				      buf));
567 			device->cap._BQC = device->cap._BCQ = 0;
568 		} else {
569 			/*
570 			 * Fixme:
571 			 * should we return an error or ignore this failure?
572 			 * dev->brightness->curr is a cached value which stores
573 			 * the correct current backlight level in most cases.
574 			 * ACPI video backlight still works w/ buggy _BQC.
575 			 * http://bugzilla.kernel.org/show_bug.cgi?id=12233
576 			 */
577 			ACPI_WARNING((AE_INFO, "Evaluating %s failed", buf));
578 			device->cap._BQC = device->cap._BCQ = 0;
579 		}
580 	}
581 
582 	*level = device->brightness->curr;
583 	return 0;
584 }
585 
586 static int
587 acpi_video_device_EDID(struct acpi_video_device *device,
588 		       union acpi_object **edid, ssize_t length)
589 {
590 	int status;
591 	struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
592 	union acpi_object *obj;
593 	union acpi_object arg0 = { ACPI_TYPE_INTEGER };
594 	struct acpi_object_list args = { 1, &arg0 };
595 
596 
597 	*edid = NULL;
598 
599 	if (!device)
600 		return -ENODEV;
601 	if (length == 128)
602 		arg0.integer.value = 1;
603 	else if (length == 256)
604 		arg0.integer.value = 2;
605 	else
606 		return -EINVAL;
607 
608 	status = acpi_evaluate_object(device->dev->handle, "_DDC", &args, &buffer);
609 	if (ACPI_FAILURE(status))
610 		return -ENODEV;
611 
612 	obj = buffer.pointer;
613 
614 	if (obj && obj->type == ACPI_TYPE_BUFFER)
615 		*edid = obj;
616 	else {
617 		printk(KERN_ERR PREFIX "Invalid _DDC data\n");
618 		status = -EFAULT;
619 		kfree(obj);
620 	}
621 
622 	return status;
623 }
624 
625 /* bus */
626 
627 /*
628  *  Arg:
629  *	video		: video bus device pointer
630  *	bios_flag	:
631  *		0.	The system BIOS should NOT automatically switch(toggle)
632  *			the active display output.
633  *		1.	The system BIOS should automatically switch (toggle) the
634  *			active display output. No switch event.
635  *		2.	The _DGS value should be locked.
636  *		3.	The system BIOS should not automatically switch (toggle) the
637  *			active display output, but instead generate the display switch
638  *			event notify code.
639  *	lcd_flag	:
640  *		0.	The system BIOS should automatically control the brightness level
641  *			of the LCD when the power changes from AC to DC
642  *		1.	The system BIOS should NOT automatically control the brightness
643  *			level of the LCD when the power changes from AC to DC.
644  *  Return Value:
645  *		-EINVAL	wrong arg.
646  */
647 
648 static int
649 acpi_video_bus_DOS(struct acpi_video_bus *video, int bios_flag, int lcd_flag)
650 {
651 	acpi_status status;
652 
653 	if (!video->cap._DOS)
654 		return 0;
655 
656 	if (bios_flag < 0 || bios_flag > 3 || lcd_flag < 0 || lcd_flag > 1)
657 		return -EINVAL;
658 	video->dos_setting = (lcd_flag << 2) | bios_flag;
659 	status = acpi_execute_simple_method(video->device->handle, "_DOS",
660 					    (lcd_flag << 2) | bios_flag);
661 	if (ACPI_FAILURE(status))
662 		return -EIO;
663 
664 	return 0;
665 }
666 
667 /*
668  * Simple comparison function used to sort backlight levels.
669  */
670 
671 static int
672 acpi_video_cmp_level(const void *a, const void *b)
673 {
674 	return *(int *)a - *(int *)b;
675 }
676 
677 /*
678  * Decides if _BQC/_BCQ for this system is usable
679  *
680  * We do this by changing the level first and then read out the current
681  * brightness level, if the value does not match, find out if it is using
682  * index. If not, clear the _BQC/_BCQ capability.
683  */
684 static int acpi_video_bqc_quirk(struct acpi_video_device *device,
685 				int max_level, int current_level)
686 {
687 	struct acpi_video_device_brightness *br = device->brightness;
688 	int result;
689 	unsigned long long level;
690 	int test_level;
691 
692 	/* don't mess with existing known broken systems */
693 	if (bqc_offset_aml_bug_workaround)
694 		return 0;
695 
696 	/*
697 	 * Some systems always report current brightness level as maximum
698 	 * through _BQC, we need to test another value for them.
699 	 */
700 	test_level = current_level == max_level ? br->levels[3] : max_level;
701 
702 	result = acpi_video_device_lcd_set_level(device, test_level);
703 	if (result)
704 		return result;
705 
706 	result = acpi_video_device_lcd_get_level_current(device, &level, true);
707 	if (result)
708 		return result;
709 
710 	if (level != test_level) {
711 		/* buggy _BQC found, need to find out if it uses index */
712 		if (level < br->count) {
713 			if (br->flags._BCL_reversed)
714 				level = br->count - 3 - level;
715 			if (br->levels[level + 2] == test_level)
716 				br->flags._BQC_use_index = 1;
717 		}
718 
719 		if (!br->flags._BQC_use_index)
720 			device->cap._BQC = device->cap._BCQ = 0;
721 	}
722 
723 	return 0;
724 }
725 
726 
727 /*
728  *  Arg:
729  *	device	: video output device (LCD, CRT, ..)
730  *
731  *  Return Value:
732  *	Maximum brightness level
733  *
734  *  Allocate and initialize device->brightness.
735  */
736 
737 static int
738 acpi_video_init_brightness(struct acpi_video_device *device)
739 {
740 	union acpi_object *obj = NULL;
741 	int i, max_level = 0, count = 0, level_ac_battery = 0;
742 	unsigned long long level, level_old;
743 	union acpi_object *o;
744 	struct acpi_video_device_brightness *br = NULL;
745 	int result = -EINVAL;
746 	u32 value;
747 
748 	if (!ACPI_SUCCESS(acpi_video_device_lcd_query_levels(device, &obj))) {
749 		ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Could not query available "
750 						"LCD brightness level\n"));
751 		goto out;
752 	}
753 
754 	if (obj->package.count < 2)
755 		goto out;
756 
757 	br = kzalloc(sizeof(*br), GFP_KERNEL);
758 	if (!br) {
759 		printk(KERN_ERR "can't allocate memory\n");
760 		result = -ENOMEM;
761 		goto out;
762 	}
763 
764 	br->levels = kmalloc((obj->package.count + 2) * sizeof *(br->levels),
765 				GFP_KERNEL);
766 	if (!br->levels) {
767 		result = -ENOMEM;
768 		goto out_free;
769 	}
770 
771 	for (i = 0; i < obj->package.count; i++) {
772 		o = (union acpi_object *)&obj->package.elements[i];
773 		if (o->type != ACPI_TYPE_INTEGER) {
774 			printk(KERN_ERR PREFIX "Invalid data\n");
775 			continue;
776 		}
777 		value = (u32) o->integer.value;
778 		/* Skip duplicate entries */
779 		if (count > 2 && br->levels[count - 1] == value)
780 			continue;
781 
782 		br->levels[count] = value;
783 
784 		if (br->levels[count] > max_level)
785 			max_level = br->levels[count];
786 		count++;
787 	}
788 
789 	/*
790 	 * some buggy BIOS don't export the levels
791 	 * when machine is on AC/Battery in _BCL package.
792 	 * In this case, the first two elements in _BCL packages
793 	 * are also supported brightness levels that OS should take care of.
794 	 */
795 	for (i = 2; i < count; i++) {
796 		if (br->levels[i] == br->levels[0])
797 			level_ac_battery++;
798 		if (br->levels[i] == br->levels[1])
799 			level_ac_battery++;
800 	}
801 
802 	if (level_ac_battery < 2) {
803 		level_ac_battery = 2 - level_ac_battery;
804 		br->flags._BCL_no_ac_battery_levels = 1;
805 		for (i = (count - 1 + level_ac_battery); i >= 2; i--)
806 			br->levels[i] = br->levels[i - level_ac_battery];
807 		count += level_ac_battery;
808 	} else if (level_ac_battery > 2)
809 		ACPI_ERROR((AE_INFO, "Too many duplicates in _BCL package"));
810 
811 	/* Check if the _BCL package is in a reversed order */
812 	if (max_level == br->levels[2]) {
813 		br->flags._BCL_reversed = 1;
814 		sort(&br->levels[2], count - 2, sizeof(br->levels[2]),
815 			acpi_video_cmp_level, NULL);
816 	} else if (max_level != br->levels[count - 1])
817 		ACPI_ERROR((AE_INFO,
818 			    "Found unordered _BCL package"));
819 
820 	br->count = count;
821 	device->brightness = br;
822 
823 	/* _BQC uses INDEX while _BCL uses VALUE in some laptops */
824 	br->curr = level = max_level;
825 
826 	if (!device->cap._BQC)
827 		goto set_level;
828 
829 	result = acpi_video_device_lcd_get_level_current(device,
830 							 &level_old, true);
831 	if (result)
832 		goto out_free_levels;
833 
834 	result = acpi_video_bqc_quirk(device, max_level, level_old);
835 	if (result)
836 		goto out_free_levels;
837 	/*
838 	 * cap._BQC may get cleared due to _BQC is found to be broken
839 	 * in acpi_video_bqc_quirk, so check again here.
840 	 */
841 	if (!device->cap._BQC)
842 		goto set_level;
843 
844 	level = acpi_video_bqc_value_to_level(device, level_old);
845 	/*
846 	 * On some buggy laptops, _BQC returns an uninitialized
847 	 * value when invoked for the first time, i.e.
848 	 * level_old is invalid (no matter whether it's a level
849 	 * or an index). Set the backlight to max_level in this case.
850 	 */
851 	for (i = 2; i < br->count; i++)
852 		if (level == br->levels[i])
853 			break;
854 	if (i == br->count || !level)
855 		level = max_level;
856 
857 set_level:
858 	result = acpi_video_device_lcd_set_level(device, level);
859 	if (result)
860 		goto out_free_levels;
861 
862 	ACPI_DEBUG_PRINT((ACPI_DB_INFO,
863 			  "found %d brightness levels\n", count - 2));
864 	kfree(obj);
865 	return result;
866 
867 out_free_levels:
868 	kfree(br->levels);
869 out_free:
870 	kfree(br);
871 out:
872 	device->brightness = NULL;
873 	kfree(obj);
874 	return result;
875 }
876 
877 /*
878  *  Arg:
879  *	device	: video output device (LCD, CRT, ..)
880  *
881  *  Return Value:
882  *	None
883  *
884  *  Find out all required AML methods defined under the output
885  *  device.
886  */
887 
888 static void acpi_video_device_find_cap(struct acpi_video_device *device)
889 {
890 	if (acpi_has_method(device->dev->handle, "_ADR"))
891 		device->cap._ADR = 1;
892 	if (acpi_has_method(device->dev->handle, "_BCL"))
893 		device->cap._BCL = 1;
894 	if (acpi_has_method(device->dev->handle, "_BCM"))
895 		device->cap._BCM = 1;
896 	if (acpi_has_method(device->dev->handle, "_BQC")) {
897 		device->cap._BQC = 1;
898 	} else if (acpi_has_method(device->dev->handle, "_BCQ")) {
899 		printk(KERN_WARNING FW_BUG "_BCQ is used instead of _BQC\n");
900 		device->cap._BCQ = 1;
901 	}
902 
903 	if (acpi_has_method(device->dev->handle, "_DDC"))
904 		device->cap._DDC = 1;
905 }
906 
907 /*
908  *  Arg:
909  *	device	: video output device (VGA)
910  *
911  *  Return Value:
912  *	None
913  *
914  *  Find out all required AML methods defined under the video bus device.
915  */
916 
917 static void acpi_video_bus_find_cap(struct acpi_video_bus *video)
918 {
919 	if (acpi_has_method(video->device->handle, "_DOS"))
920 		video->cap._DOS = 1;
921 	if (acpi_has_method(video->device->handle, "_DOD"))
922 		video->cap._DOD = 1;
923 	if (acpi_has_method(video->device->handle, "_ROM"))
924 		video->cap._ROM = 1;
925 	if (acpi_has_method(video->device->handle, "_GPD"))
926 		video->cap._GPD = 1;
927 	if (acpi_has_method(video->device->handle, "_SPD"))
928 		video->cap._SPD = 1;
929 	if (acpi_has_method(video->device->handle, "_VPO"))
930 		video->cap._VPO = 1;
931 }
932 
933 /*
934  * Check whether the video bus device has required AML method to
935  * support the desired features
936  */
937 
938 static int acpi_video_bus_check(struct acpi_video_bus *video)
939 {
940 	acpi_status status = -ENOENT;
941 	struct pci_dev *dev;
942 
943 	if (!video)
944 		return -EINVAL;
945 
946 	dev = acpi_get_pci_dev(video->device->handle);
947 	if (!dev)
948 		return -ENODEV;
949 	pci_dev_put(dev);
950 
951 	/*
952 	 * Since there is no HID, CID and so on for VGA driver, we have
953 	 * to check well known required nodes.
954 	 */
955 
956 	/* Does this device support video switching? */
957 	if (video->cap._DOS || video->cap._DOD) {
958 		if (!video->cap._DOS) {
959 			printk(KERN_WARNING FW_BUG
960 				"ACPI(%s) defines _DOD but not _DOS\n",
961 				acpi_device_bid(video->device));
962 		}
963 		video->flags.multihead = 1;
964 		status = 0;
965 	}
966 
967 	/* Does this device support retrieving a video ROM? */
968 	if (video->cap._ROM) {
969 		video->flags.rom = 1;
970 		status = 0;
971 	}
972 
973 	/* Does this device support configuring which video device to POST? */
974 	if (video->cap._GPD && video->cap._SPD && video->cap._VPO) {
975 		video->flags.post = 1;
976 		status = 0;
977 	}
978 
979 	return status;
980 }
981 
982 /*
983  * --------------------------------------------------------------------------
984  *                               Driver Interface
985  * --------------------------------------------------------------------------
986  */
987 
988 /* device interface */
989 static struct acpi_video_device_attrib *
990 acpi_video_get_device_attr(struct acpi_video_bus *video, unsigned long device_id)
991 {
992 	struct acpi_video_enumerated_device *ids;
993 	int i;
994 
995 	for (i = 0; i < video->attached_count; i++) {
996 		ids = &video->attached_array[i];
997 		if ((ids->value.int_val & 0xffff) == device_id)
998 			return &ids->value.attrib;
999 	}
1000 
1001 	return NULL;
1002 }
1003 
1004 static int
1005 acpi_video_get_device_type(struct acpi_video_bus *video,
1006 			   unsigned long device_id)
1007 {
1008 	struct acpi_video_enumerated_device *ids;
1009 	int i;
1010 
1011 	for (i = 0; i < video->attached_count; i++) {
1012 		ids = &video->attached_array[i];
1013 		if ((ids->value.int_val & 0xffff) == device_id)
1014 			return ids->value.int_val;
1015 	}
1016 
1017 	return 0;
1018 }
1019 
1020 static int
1021 acpi_video_bus_get_one_device(struct acpi_device *device,
1022 			      struct acpi_video_bus *video)
1023 {
1024 	unsigned long long device_id;
1025 	int status, device_type;
1026 	struct acpi_video_device *data;
1027 	struct acpi_video_device_attrib *attribute;
1028 
1029 	status =
1030 	    acpi_evaluate_integer(device->handle, "_ADR", NULL, &device_id);
1031 	/* Some device omits _ADR, we skip them instead of fail */
1032 	if (ACPI_FAILURE(status))
1033 		return 0;
1034 
1035 	data = kzalloc(sizeof(struct acpi_video_device), GFP_KERNEL);
1036 	if (!data)
1037 		return -ENOMEM;
1038 
1039 	strcpy(acpi_device_name(device), ACPI_VIDEO_DEVICE_NAME);
1040 	strcpy(acpi_device_class(device), ACPI_VIDEO_CLASS);
1041 	device->driver_data = data;
1042 
1043 	data->device_id = device_id;
1044 	data->video = video;
1045 	data->dev = device;
1046 	INIT_DELAYED_WORK(&data->switch_brightness_work,
1047 			  acpi_video_switch_brightness);
1048 
1049 	attribute = acpi_video_get_device_attr(video, device_id);
1050 
1051 	if (attribute && (attribute->device_id_scheme || device_id_scheme)) {
1052 		switch (attribute->display_type) {
1053 		case ACPI_VIDEO_DISPLAY_CRT:
1054 			data->flags.crt = 1;
1055 			break;
1056 		case ACPI_VIDEO_DISPLAY_TV:
1057 			data->flags.tvout = 1;
1058 			break;
1059 		case ACPI_VIDEO_DISPLAY_DVI:
1060 			data->flags.dvi = 1;
1061 			break;
1062 		case ACPI_VIDEO_DISPLAY_LCD:
1063 			data->flags.lcd = 1;
1064 			break;
1065 		default:
1066 			data->flags.unknown = 1;
1067 			break;
1068 		}
1069 		if (attribute->bios_can_detect)
1070 			data->flags.bios = 1;
1071 	} else {
1072 		/* Check for legacy IDs */
1073 		device_type = acpi_video_get_device_type(video, device_id);
1074 		/* Ignore bits 16 and 18-20 */
1075 		switch (device_type & 0xffe2ffff) {
1076 		case ACPI_VIDEO_DISPLAY_LEGACY_MONITOR:
1077 			data->flags.crt = 1;
1078 			break;
1079 		case ACPI_VIDEO_DISPLAY_LEGACY_PANEL:
1080 			data->flags.lcd = 1;
1081 			break;
1082 		case ACPI_VIDEO_DISPLAY_LEGACY_TV:
1083 			data->flags.tvout = 1;
1084 			break;
1085 		default:
1086 			data->flags.unknown = 1;
1087 		}
1088 	}
1089 
1090 	acpi_video_device_bind(video, data);
1091 	acpi_video_device_find_cap(data);
1092 
1093 	mutex_lock(&video->device_list_lock);
1094 	list_add_tail(&data->entry, &video->video_device_list);
1095 	mutex_unlock(&video->device_list_lock);
1096 
1097 	return status;
1098 }
1099 
1100 /*
1101  *  Arg:
1102  *	video	: video bus device
1103  *
1104  *  Return:
1105  *	none
1106  *
1107  *  Enumerate the video device list of the video bus,
1108  *  bind the ids with the corresponding video devices
1109  *  under the video bus.
1110  */
1111 
1112 static void acpi_video_device_rebind(struct acpi_video_bus *video)
1113 {
1114 	struct acpi_video_device *dev;
1115 
1116 	mutex_lock(&video->device_list_lock);
1117 
1118 	list_for_each_entry(dev, &video->video_device_list, entry)
1119 		acpi_video_device_bind(video, dev);
1120 
1121 	mutex_unlock(&video->device_list_lock);
1122 }
1123 
1124 /*
1125  *  Arg:
1126  *	video	: video bus device
1127  *	device	: video output device under the video
1128  *		bus
1129  *
1130  *  Return:
1131  *	none
1132  *
1133  *  Bind the ids with the corresponding video devices
1134  *  under the video bus.
1135  */
1136 
1137 static void
1138 acpi_video_device_bind(struct acpi_video_bus *video,
1139 		       struct acpi_video_device *device)
1140 {
1141 	struct acpi_video_enumerated_device *ids;
1142 	int i;
1143 
1144 	for (i = 0; i < video->attached_count; i++) {
1145 		ids = &video->attached_array[i];
1146 		if (device->device_id == (ids->value.int_val & 0xffff)) {
1147 			ids->bind_info = device;
1148 			ACPI_DEBUG_PRINT((ACPI_DB_INFO, "device_bind %d\n", i));
1149 		}
1150 	}
1151 }
1152 
1153 static bool acpi_video_device_in_dod(struct acpi_video_device *device)
1154 {
1155 	struct acpi_video_bus *video = device->video;
1156 	int i;
1157 
1158 	/*
1159 	 * If we have a broken _DOD or we have more than 8 output devices
1160 	 * under the graphics controller node that we can't proper deal with
1161 	 * in the operation region code currently, no need to test.
1162 	 */
1163 	if (!video->attached_count || video->child_count > 8)
1164 		return true;
1165 
1166 	for (i = 0; i < video->attached_count; i++) {
1167 		if ((video->attached_array[i].value.int_val & 0xfff) ==
1168 		    (device->device_id & 0xfff))
1169 			return true;
1170 	}
1171 
1172 	return false;
1173 }
1174 
1175 /*
1176  *  Arg:
1177  *	video	: video bus device
1178  *
1179  *  Return:
1180  *	< 0	: error
1181  *
1182  *  Call _DOD to enumerate all devices attached to display adapter
1183  *
1184  */
1185 
1186 static int acpi_video_device_enumerate(struct acpi_video_bus *video)
1187 {
1188 	int status;
1189 	int count;
1190 	int i;
1191 	struct acpi_video_enumerated_device *active_list;
1192 	struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
1193 	union acpi_object *dod = NULL;
1194 	union acpi_object *obj;
1195 
1196 	status = acpi_evaluate_object(video->device->handle, "_DOD", NULL, &buffer);
1197 	if (!ACPI_SUCCESS(status)) {
1198 		ACPI_EXCEPTION((AE_INFO, status, "Evaluating _DOD"));
1199 		return status;
1200 	}
1201 
1202 	dod = buffer.pointer;
1203 	if (!dod || (dod->type != ACPI_TYPE_PACKAGE)) {
1204 		ACPI_EXCEPTION((AE_INFO, status, "Invalid _DOD data"));
1205 		status = -EFAULT;
1206 		goto out;
1207 	}
1208 
1209 	ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Found %d video heads in _DOD\n",
1210 			  dod->package.count));
1211 
1212 	active_list = kcalloc(1 + dod->package.count,
1213 			      sizeof(struct acpi_video_enumerated_device),
1214 			      GFP_KERNEL);
1215 	if (!active_list) {
1216 		status = -ENOMEM;
1217 		goto out;
1218 	}
1219 
1220 	count = 0;
1221 	for (i = 0; i < dod->package.count; i++) {
1222 		obj = &dod->package.elements[i];
1223 
1224 		if (obj->type != ACPI_TYPE_INTEGER) {
1225 			printk(KERN_ERR PREFIX
1226 				"Invalid _DOD data in element %d\n", i);
1227 			continue;
1228 		}
1229 
1230 		active_list[count].value.int_val = obj->integer.value;
1231 		active_list[count].bind_info = NULL;
1232 		ACPI_DEBUG_PRINT((ACPI_DB_INFO, "dod element[%d] = %d\n", i,
1233 				  (int)obj->integer.value));
1234 		count++;
1235 	}
1236 
1237 	kfree(video->attached_array);
1238 
1239 	video->attached_array = active_list;
1240 	video->attached_count = count;
1241 
1242 out:
1243 	kfree(buffer.pointer);
1244 	return status;
1245 }
1246 
1247 static int
1248 acpi_video_get_next_level(struct acpi_video_device *device,
1249 			  u32 level_current, u32 event)
1250 {
1251 	int min, max, min_above, max_below, i, l, delta = 255;
1252 	max = max_below = 0;
1253 	min = min_above = 255;
1254 	/* Find closest level to level_current */
1255 	for (i = 2; i < device->brightness->count; i++) {
1256 		l = device->brightness->levels[i];
1257 		if (abs(l - level_current) < abs(delta)) {
1258 			delta = l - level_current;
1259 			if (!delta)
1260 				break;
1261 		}
1262 	}
1263 	/* Ajust level_current to closest available level */
1264 	level_current += delta;
1265 	for (i = 2; i < device->brightness->count; i++) {
1266 		l = device->brightness->levels[i];
1267 		if (l < min)
1268 			min = l;
1269 		if (l > max)
1270 			max = l;
1271 		if (l < min_above && l > level_current)
1272 			min_above = l;
1273 		if (l > max_below && l < level_current)
1274 			max_below = l;
1275 	}
1276 
1277 	switch (event) {
1278 	case ACPI_VIDEO_NOTIFY_CYCLE_BRIGHTNESS:
1279 		return (level_current < max) ? min_above : min;
1280 	case ACPI_VIDEO_NOTIFY_INC_BRIGHTNESS:
1281 		return (level_current < max) ? min_above : max;
1282 	case ACPI_VIDEO_NOTIFY_DEC_BRIGHTNESS:
1283 		return (level_current > min) ? max_below : min;
1284 	case ACPI_VIDEO_NOTIFY_ZERO_BRIGHTNESS:
1285 	case ACPI_VIDEO_NOTIFY_DISPLAY_OFF:
1286 		return 0;
1287 	default:
1288 		return level_current;
1289 	}
1290 }
1291 
1292 static void
1293 acpi_video_switch_brightness(struct work_struct *work)
1294 {
1295 	struct acpi_video_device *device = container_of(to_delayed_work(work),
1296 			     struct acpi_video_device, switch_brightness_work);
1297 	unsigned long long level_current, level_next;
1298 	int event = device->switch_brightness_event;
1299 	int result = -EINVAL;
1300 
1301 	/* no warning message if acpi_backlight=vendor or a quirk is used */
1302 	if (!device->backlight)
1303 		return;
1304 
1305 	if (!device->brightness)
1306 		goto out;
1307 
1308 	result = acpi_video_device_lcd_get_level_current(device,
1309 							 &level_current,
1310 							 false);
1311 	if (result)
1312 		goto out;
1313 
1314 	level_next = acpi_video_get_next_level(device, level_current, event);
1315 
1316 	result = acpi_video_device_lcd_set_level(device, level_next);
1317 
1318 	if (!result)
1319 		backlight_force_update(device->backlight,
1320 				       BACKLIGHT_UPDATE_HOTKEY);
1321 
1322 out:
1323 	if (result)
1324 		printk(KERN_ERR PREFIX "Failed to switch the brightness\n");
1325 }
1326 
1327 int acpi_video_get_edid(struct acpi_device *device, int type, int device_id,
1328 			void **edid)
1329 {
1330 	struct acpi_video_bus *video;
1331 	struct acpi_video_device *video_device;
1332 	union acpi_object *buffer = NULL;
1333 	acpi_status status;
1334 	int i, length;
1335 
1336 	if (!device || !acpi_driver_data(device))
1337 		return -EINVAL;
1338 
1339 	video = acpi_driver_data(device);
1340 
1341 	for (i = 0; i < video->attached_count; i++) {
1342 		video_device = video->attached_array[i].bind_info;
1343 		length = 256;
1344 
1345 		if (!video_device)
1346 			continue;
1347 
1348 		if (!video_device->cap._DDC)
1349 			continue;
1350 
1351 		if (type) {
1352 			switch (type) {
1353 			case ACPI_VIDEO_DISPLAY_CRT:
1354 				if (!video_device->flags.crt)
1355 					continue;
1356 				break;
1357 			case ACPI_VIDEO_DISPLAY_TV:
1358 				if (!video_device->flags.tvout)
1359 					continue;
1360 				break;
1361 			case ACPI_VIDEO_DISPLAY_DVI:
1362 				if (!video_device->flags.dvi)
1363 					continue;
1364 				break;
1365 			case ACPI_VIDEO_DISPLAY_LCD:
1366 				if (!video_device->flags.lcd)
1367 					continue;
1368 				break;
1369 			}
1370 		} else if (video_device->device_id != device_id) {
1371 			continue;
1372 		}
1373 
1374 		status = acpi_video_device_EDID(video_device, &buffer, length);
1375 
1376 		if (ACPI_FAILURE(status) || !buffer ||
1377 		    buffer->type != ACPI_TYPE_BUFFER) {
1378 			length = 128;
1379 			status = acpi_video_device_EDID(video_device, &buffer,
1380 							length);
1381 			if (ACPI_FAILURE(status) || !buffer ||
1382 			    buffer->type != ACPI_TYPE_BUFFER) {
1383 				continue;
1384 			}
1385 		}
1386 
1387 		*edid = buffer->buffer.pointer;
1388 		return length;
1389 	}
1390 
1391 	return -ENODEV;
1392 }
1393 EXPORT_SYMBOL(acpi_video_get_edid);
1394 
1395 static int
1396 acpi_video_bus_get_devices(struct acpi_video_bus *video,
1397 			   struct acpi_device *device)
1398 {
1399 	int status = 0;
1400 	struct acpi_device *dev;
1401 
1402 	/*
1403 	 * There are systems where video module known to work fine regardless
1404 	 * of broken _DOD and ignoring returned value here doesn't cause
1405 	 * any issues later.
1406 	 */
1407 	acpi_video_device_enumerate(video);
1408 
1409 	list_for_each_entry(dev, &device->children, node) {
1410 
1411 		status = acpi_video_bus_get_one_device(dev, video);
1412 		if (status) {
1413 			dev_err(&dev->dev, "Can't attach device\n");
1414 			break;
1415 		}
1416 		video->child_count++;
1417 	}
1418 	return status;
1419 }
1420 
1421 /* acpi_video interface */
1422 
1423 /*
1424  * Win8 requires setting bit2 of _DOS to let firmware know it shouldn't
1425  * preform any automatic brightness change on receiving a notification.
1426  */
1427 static int acpi_video_bus_start_devices(struct acpi_video_bus *video)
1428 {
1429 	return acpi_video_bus_DOS(video, 0,
1430 				  acpi_osi_is_win8() ? 1 : 0);
1431 }
1432 
1433 static int acpi_video_bus_stop_devices(struct acpi_video_bus *video)
1434 {
1435 	return acpi_video_bus_DOS(video, 0,
1436 				  acpi_osi_is_win8() ? 0 : 1);
1437 }
1438 
1439 static void acpi_video_bus_notify(struct acpi_device *device, u32 event)
1440 {
1441 	struct acpi_video_bus *video = acpi_driver_data(device);
1442 	struct input_dev *input;
1443 	int keycode = 0;
1444 
1445 	if (!video || !video->input)
1446 		return;
1447 
1448 	input = video->input;
1449 
1450 	switch (event) {
1451 	case ACPI_VIDEO_NOTIFY_SWITCH:	/* User requested a switch,
1452 					 * most likely via hotkey. */
1453 		keycode = KEY_SWITCHVIDEOMODE;
1454 		break;
1455 
1456 	case ACPI_VIDEO_NOTIFY_PROBE:	/* User plugged in or removed a video
1457 					 * connector. */
1458 		acpi_video_device_enumerate(video);
1459 		acpi_video_device_rebind(video);
1460 		keycode = KEY_SWITCHVIDEOMODE;
1461 		break;
1462 
1463 	case ACPI_VIDEO_NOTIFY_CYCLE:	/* Cycle Display output hotkey pressed. */
1464 		keycode = KEY_SWITCHVIDEOMODE;
1465 		break;
1466 	case ACPI_VIDEO_NOTIFY_NEXT_OUTPUT:	/* Next Display output hotkey pressed. */
1467 		keycode = KEY_VIDEO_NEXT;
1468 		break;
1469 	case ACPI_VIDEO_NOTIFY_PREV_OUTPUT:	/* previous Display output hotkey pressed. */
1470 		keycode = KEY_VIDEO_PREV;
1471 		break;
1472 
1473 	default:
1474 		ACPI_DEBUG_PRINT((ACPI_DB_INFO,
1475 				  "Unsupported event [0x%x]\n", event));
1476 		break;
1477 	}
1478 
1479 	if (acpi_notifier_call_chain(device, event, 0))
1480 		/* Something vetoed the keypress. */
1481 		keycode = 0;
1482 
1483 	if (keycode) {
1484 		input_report_key(input, keycode, 1);
1485 		input_sync(input);
1486 		input_report_key(input, keycode, 0);
1487 		input_sync(input);
1488 	}
1489 
1490 	return;
1491 }
1492 
1493 static void brightness_switch_event(struct acpi_video_device *video_device,
1494 				    u32 event)
1495 {
1496 	if (!brightness_switch_enabled)
1497 		return;
1498 
1499 	video_device->switch_brightness_event = event;
1500 	schedule_delayed_work(&video_device->switch_brightness_work, HZ / 10);
1501 }
1502 
1503 static void acpi_video_device_notify(acpi_handle handle, u32 event, void *data)
1504 {
1505 	struct acpi_video_device *video_device = data;
1506 	struct acpi_device *device = NULL;
1507 	struct acpi_video_bus *bus;
1508 	struct input_dev *input;
1509 	int keycode = 0;
1510 
1511 	if (!video_device)
1512 		return;
1513 
1514 	device = video_device->dev;
1515 	bus = video_device->video;
1516 	input = bus->input;
1517 
1518 	switch (event) {
1519 	case ACPI_VIDEO_NOTIFY_CYCLE_BRIGHTNESS:	/* Cycle brightness */
1520 		brightness_switch_event(video_device, event);
1521 		keycode = KEY_BRIGHTNESS_CYCLE;
1522 		break;
1523 	case ACPI_VIDEO_NOTIFY_INC_BRIGHTNESS:	/* Increase brightness */
1524 		brightness_switch_event(video_device, event);
1525 		keycode = KEY_BRIGHTNESSUP;
1526 		break;
1527 	case ACPI_VIDEO_NOTIFY_DEC_BRIGHTNESS:	/* Decrease brightness */
1528 		brightness_switch_event(video_device, event);
1529 		keycode = KEY_BRIGHTNESSDOWN;
1530 		break;
1531 	case ACPI_VIDEO_NOTIFY_ZERO_BRIGHTNESS:	/* zero brightness */
1532 		brightness_switch_event(video_device, event);
1533 		keycode = KEY_BRIGHTNESS_ZERO;
1534 		break;
1535 	case ACPI_VIDEO_NOTIFY_DISPLAY_OFF:	/* display device off */
1536 		brightness_switch_event(video_device, event);
1537 		keycode = KEY_DISPLAY_OFF;
1538 		break;
1539 	default:
1540 		ACPI_DEBUG_PRINT((ACPI_DB_INFO,
1541 				  "Unsupported event [0x%x]\n", event));
1542 		break;
1543 	}
1544 
1545 	acpi_notifier_call_chain(device, event, 0);
1546 
1547 	if (keycode) {
1548 		input_report_key(input, keycode, 1);
1549 		input_sync(input);
1550 		input_report_key(input, keycode, 0);
1551 		input_sync(input);
1552 	}
1553 
1554 	return;
1555 }
1556 
1557 static int acpi_video_resume(struct notifier_block *nb,
1558 				unsigned long val, void *ign)
1559 {
1560 	struct acpi_video_bus *video;
1561 	struct acpi_video_device *video_device;
1562 	int i;
1563 
1564 	switch (val) {
1565 	case PM_HIBERNATION_PREPARE:
1566 	case PM_SUSPEND_PREPARE:
1567 	case PM_RESTORE_PREPARE:
1568 		return NOTIFY_DONE;
1569 	}
1570 
1571 	video = container_of(nb, struct acpi_video_bus, pm_nb);
1572 
1573 	dev_info(&video->device->dev, "Restoring backlight state\n");
1574 
1575 	for (i = 0; i < video->attached_count; i++) {
1576 		video_device = video->attached_array[i].bind_info;
1577 		if (video_device && video_device->brightness)
1578 			acpi_video_device_lcd_set_level(video_device,
1579 					video_device->brightness->curr);
1580 	}
1581 
1582 	return NOTIFY_OK;
1583 }
1584 
1585 static acpi_status
1586 acpi_video_bus_match(acpi_handle handle, u32 level, void *context,
1587 			void **return_value)
1588 {
1589 	struct acpi_device *device = context;
1590 	struct acpi_device *sibling;
1591 	int result;
1592 
1593 	if (handle == device->handle)
1594 		return AE_CTRL_TERMINATE;
1595 
1596 	result = acpi_bus_get_device(handle, &sibling);
1597 	if (result)
1598 		return AE_OK;
1599 
1600 	if (!strcmp(acpi_device_name(sibling), ACPI_VIDEO_BUS_NAME))
1601 			return AE_ALREADY_EXISTS;
1602 
1603 	return AE_OK;
1604 }
1605 
1606 static void acpi_video_dev_register_backlight(struct acpi_video_device *device)
1607 {
1608 	struct backlight_properties props;
1609 	struct pci_dev *pdev;
1610 	acpi_handle acpi_parent;
1611 	struct device *parent = NULL;
1612 	int result;
1613 	static int count;
1614 	char *name;
1615 
1616 	result = acpi_video_init_brightness(device);
1617 	if (result)
1618 		return;
1619 
1620 	if (disable_backlight_sysfs_if > 0)
1621 		return;
1622 
1623 	name = kasprintf(GFP_KERNEL, "acpi_video%d", count);
1624 	if (!name)
1625 		return;
1626 	count++;
1627 
1628 	acpi_get_parent(device->dev->handle, &acpi_parent);
1629 
1630 	pdev = acpi_get_pci_dev(acpi_parent);
1631 	if (pdev) {
1632 		parent = &pdev->dev;
1633 		pci_dev_put(pdev);
1634 	}
1635 
1636 	memset(&props, 0, sizeof(struct backlight_properties));
1637 	props.type = BACKLIGHT_FIRMWARE;
1638 	props.max_brightness = device->brightness->count - 3;
1639 	device->backlight = backlight_device_register(name,
1640 						      parent,
1641 						      device,
1642 						      &acpi_backlight_ops,
1643 						      &props);
1644 	kfree(name);
1645 	if (IS_ERR(device->backlight)) {
1646 		device->backlight = NULL;
1647 		return;
1648 	}
1649 
1650 	/*
1651 	 * Save current brightness level in case we have to restore it
1652 	 * before acpi_video_device_lcd_set_level() is called next time.
1653 	 */
1654 	device->backlight->props.brightness =
1655 			acpi_video_get_brightness(device->backlight);
1656 
1657 	device->cooling_dev = thermal_cooling_device_register("LCD",
1658 				device->dev, &video_cooling_ops);
1659 	if (IS_ERR(device->cooling_dev)) {
1660 		/*
1661 		 * Set cooling_dev to NULL so we don't crash trying to free it.
1662 		 * Also, why the hell we are returning early and not attempt to
1663 		 * register video output if cooling device registration failed?
1664 		 * -- dtor
1665 		 */
1666 		device->cooling_dev = NULL;
1667 		return;
1668 	}
1669 
1670 	dev_info(&device->dev->dev, "registered as cooling_device%d\n",
1671 		 device->cooling_dev->id);
1672 	result = sysfs_create_link(&device->dev->dev.kobj,
1673 			&device->cooling_dev->device.kobj,
1674 			"thermal_cooling");
1675 	if (result)
1676 		printk(KERN_ERR PREFIX "Create sysfs link\n");
1677 	result = sysfs_create_link(&device->cooling_dev->device.kobj,
1678 			&device->dev->dev.kobj, "device");
1679 	if (result)
1680 		printk(KERN_ERR PREFIX "Create sysfs link\n");
1681 }
1682 
1683 static void acpi_video_run_bcl_for_osi(struct acpi_video_bus *video)
1684 {
1685 	struct acpi_video_device *dev;
1686 	union acpi_object *levels;
1687 
1688 	mutex_lock(&video->device_list_lock);
1689 	list_for_each_entry(dev, &video->video_device_list, entry) {
1690 		if (!acpi_video_device_lcd_query_levels(dev, &levels))
1691 			kfree(levels);
1692 	}
1693 	mutex_unlock(&video->device_list_lock);
1694 }
1695 
1696 static bool acpi_video_should_register_backlight(struct acpi_video_device *dev)
1697 {
1698 	/*
1699 	 * Do not create backlight device for video output
1700 	 * device that is not in the enumerated list.
1701 	 */
1702 	if (!acpi_video_device_in_dod(dev)) {
1703 		dev_dbg(&dev->dev->dev, "not in _DOD list, ignore\n");
1704 		return false;
1705 	}
1706 
1707 	if (only_lcd)
1708 		return dev->flags.lcd;
1709 	return true;
1710 }
1711 
1712 static int acpi_video_bus_register_backlight(struct acpi_video_bus *video)
1713 {
1714 	struct acpi_video_device *dev;
1715 
1716 	if (video->backlight_registered)
1717 		return 0;
1718 
1719 	acpi_video_run_bcl_for_osi(video);
1720 
1721 	if (acpi_video_get_backlight_type() != acpi_backlight_video)
1722 		return 0;
1723 
1724 	mutex_lock(&video->device_list_lock);
1725 	list_for_each_entry(dev, &video->video_device_list, entry) {
1726 		if (acpi_video_should_register_backlight(dev))
1727 			acpi_video_dev_register_backlight(dev);
1728 	}
1729 	mutex_unlock(&video->device_list_lock);
1730 
1731 	video->backlight_registered = true;
1732 
1733 	video->pm_nb.notifier_call = acpi_video_resume;
1734 	video->pm_nb.priority = 0;
1735 	return register_pm_notifier(&video->pm_nb);
1736 }
1737 
1738 static void acpi_video_dev_unregister_backlight(struct acpi_video_device *device)
1739 {
1740 	if (device->backlight) {
1741 		backlight_device_unregister(device->backlight);
1742 		device->backlight = NULL;
1743 	}
1744 	if (device->brightness) {
1745 		kfree(device->brightness->levels);
1746 		kfree(device->brightness);
1747 		device->brightness = NULL;
1748 	}
1749 	if (device->cooling_dev) {
1750 		sysfs_remove_link(&device->dev->dev.kobj, "thermal_cooling");
1751 		sysfs_remove_link(&device->cooling_dev->device.kobj, "device");
1752 		thermal_cooling_device_unregister(device->cooling_dev);
1753 		device->cooling_dev = NULL;
1754 	}
1755 }
1756 
1757 static int acpi_video_bus_unregister_backlight(struct acpi_video_bus *video)
1758 {
1759 	struct acpi_video_device *dev;
1760 	int error;
1761 
1762 	if (!video->backlight_registered)
1763 		return 0;
1764 
1765 	error = unregister_pm_notifier(&video->pm_nb);
1766 
1767 	mutex_lock(&video->device_list_lock);
1768 	list_for_each_entry(dev, &video->video_device_list, entry)
1769 		acpi_video_dev_unregister_backlight(dev);
1770 	mutex_unlock(&video->device_list_lock);
1771 
1772 	video->backlight_registered = false;
1773 
1774 	return error;
1775 }
1776 
1777 static void acpi_video_dev_add_notify_handler(struct acpi_video_device *device)
1778 {
1779 	acpi_status status;
1780 	struct acpi_device *adev = device->dev;
1781 
1782 	status = acpi_install_notify_handler(adev->handle, ACPI_DEVICE_NOTIFY,
1783 					     acpi_video_device_notify, device);
1784 	if (ACPI_FAILURE(status))
1785 		dev_err(&adev->dev, "Error installing notify handler\n");
1786 	else
1787 		device->flags.notify = 1;
1788 }
1789 
1790 static int acpi_video_bus_add_notify_handler(struct acpi_video_bus *video)
1791 {
1792 	struct input_dev *input;
1793 	struct acpi_video_device *dev;
1794 	int error;
1795 
1796 	video->input = input = input_allocate_device();
1797 	if (!input) {
1798 		error = -ENOMEM;
1799 		goto out;
1800 	}
1801 
1802 	error = acpi_video_bus_start_devices(video);
1803 	if (error)
1804 		goto err_free_input;
1805 
1806 	snprintf(video->phys, sizeof(video->phys),
1807 			"%s/video/input0", acpi_device_hid(video->device));
1808 
1809 	input->name = acpi_device_name(video->device);
1810 	input->phys = video->phys;
1811 	input->id.bustype = BUS_HOST;
1812 	input->id.product = 0x06;
1813 	input->dev.parent = &video->device->dev;
1814 	input->evbit[0] = BIT(EV_KEY);
1815 	set_bit(KEY_SWITCHVIDEOMODE, input->keybit);
1816 	set_bit(KEY_VIDEO_NEXT, input->keybit);
1817 	set_bit(KEY_VIDEO_PREV, input->keybit);
1818 	set_bit(KEY_BRIGHTNESS_CYCLE, input->keybit);
1819 	set_bit(KEY_BRIGHTNESSUP, input->keybit);
1820 	set_bit(KEY_BRIGHTNESSDOWN, input->keybit);
1821 	set_bit(KEY_BRIGHTNESS_ZERO, input->keybit);
1822 	set_bit(KEY_DISPLAY_OFF, input->keybit);
1823 
1824 	error = input_register_device(input);
1825 	if (error)
1826 		goto err_stop_dev;
1827 
1828 	mutex_lock(&video->device_list_lock);
1829 	list_for_each_entry(dev, &video->video_device_list, entry)
1830 		acpi_video_dev_add_notify_handler(dev);
1831 	mutex_unlock(&video->device_list_lock);
1832 
1833 	return 0;
1834 
1835 err_stop_dev:
1836 	acpi_video_bus_stop_devices(video);
1837 err_free_input:
1838 	input_free_device(input);
1839 	video->input = NULL;
1840 out:
1841 	return error;
1842 }
1843 
1844 static void acpi_video_dev_remove_notify_handler(struct acpi_video_device *dev)
1845 {
1846 	if (dev->flags.notify) {
1847 		acpi_remove_notify_handler(dev->dev->handle, ACPI_DEVICE_NOTIFY,
1848 					   acpi_video_device_notify);
1849 		dev->flags.notify = 0;
1850 	}
1851 }
1852 
1853 static void acpi_video_bus_remove_notify_handler(struct acpi_video_bus *video)
1854 {
1855 	struct acpi_video_device *dev;
1856 
1857 	mutex_lock(&video->device_list_lock);
1858 	list_for_each_entry(dev, &video->video_device_list, entry)
1859 		acpi_video_dev_remove_notify_handler(dev);
1860 	mutex_unlock(&video->device_list_lock);
1861 
1862 	acpi_video_bus_stop_devices(video);
1863 	input_unregister_device(video->input);
1864 	video->input = NULL;
1865 }
1866 
1867 static int acpi_video_bus_put_devices(struct acpi_video_bus *video)
1868 {
1869 	struct acpi_video_device *dev, *next;
1870 
1871 	mutex_lock(&video->device_list_lock);
1872 	list_for_each_entry_safe(dev, next, &video->video_device_list, entry) {
1873 		list_del(&dev->entry);
1874 		kfree(dev);
1875 	}
1876 	mutex_unlock(&video->device_list_lock);
1877 
1878 	return 0;
1879 }
1880 
1881 static int instance;
1882 
1883 static int acpi_video_bus_add(struct acpi_device *device)
1884 {
1885 	struct acpi_video_bus *video;
1886 	int error;
1887 	acpi_status status;
1888 
1889 	status = acpi_walk_namespace(ACPI_TYPE_DEVICE,
1890 				device->parent->handle, 1,
1891 				acpi_video_bus_match, NULL,
1892 				device, NULL);
1893 	if (status == AE_ALREADY_EXISTS) {
1894 		printk(KERN_WARNING FW_BUG
1895 			"Duplicate ACPI video bus devices for the"
1896 			" same VGA controller, please try module "
1897 			"parameter \"video.allow_duplicates=1\""
1898 			"if the current driver doesn't work.\n");
1899 		if (!allow_duplicates)
1900 			return -ENODEV;
1901 	}
1902 
1903 	video = kzalloc(sizeof(struct acpi_video_bus), GFP_KERNEL);
1904 	if (!video)
1905 		return -ENOMEM;
1906 
1907 	/* a hack to fix the duplicate name "VID" problem on T61 */
1908 	if (!strcmp(device->pnp.bus_id, "VID")) {
1909 		if (instance)
1910 			device->pnp.bus_id[3] = '0' + instance;
1911 		instance++;
1912 	}
1913 	/* a hack to fix the duplicate name "VGA" problem on Pa 3553 */
1914 	if (!strcmp(device->pnp.bus_id, "VGA")) {
1915 		if (instance)
1916 			device->pnp.bus_id[3] = '0' + instance;
1917 		instance++;
1918 	}
1919 
1920 	video->device = device;
1921 	strcpy(acpi_device_name(device), ACPI_VIDEO_BUS_NAME);
1922 	strcpy(acpi_device_class(device), ACPI_VIDEO_CLASS);
1923 	device->driver_data = video;
1924 
1925 	acpi_video_bus_find_cap(video);
1926 	error = acpi_video_bus_check(video);
1927 	if (error)
1928 		goto err_free_video;
1929 
1930 	mutex_init(&video->device_list_lock);
1931 	INIT_LIST_HEAD(&video->video_device_list);
1932 
1933 	error = acpi_video_bus_get_devices(video, device);
1934 	if (error)
1935 		goto err_put_video;
1936 
1937 	printk(KERN_INFO PREFIX "%s [%s] (multi-head: %s  rom: %s  post: %s)\n",
1938 	       ACPI_VIDEO_DEVICE_NAME, acpi_device_bid(device),
1939 	       video->flags.multihead ? "yes" : "no",
1940 	       video->flags.rom ? "yes" : "no",
1941 	       video->flags.post ? "yes" : "no");
1942 	mutex_lock(&video_list_lock);
1943 	list_add_tail(&video->entry, &video_bus_head);
1944 	mutex_unlock(&video_list_lock);
1945 
1946 	acpi_video_bus_register_backlight(video);
1947 	acpi_video_bus_add_notify_handler(video);
1948 
1949 	return 0;
1950 
1951 err_put_video:
1952 	acpi_video_bus_put_devices(video);
1953 	kfree(video->attached_array);
1954 err_free_video:
1955 	kfree(video);
1956 	device->driver_data = NULL;
1957 
1958 	return error;
1959 }
1960 
1961 static int acpi_video_bus_remove(struct acpi_device *device)
1962 {
1963 	struct acpi_video_bus *video = NULL;
1964 
1965 
1966 	if (!device || !acpi_driver_data(device))
1967 		return -EINVAL;
1968 
1969 	video = acpi_driver_data(device);
1970 
1971 	acpi_video_bus_remove_notify_handler(video);
1972 	acpi_video_bus_unregister_backlight(video);
1973 	acpi_video_bus_put_devices(video);
1974 
1975 	mutex_lock(&video_list_lock);
1976 	list_del(&video->entry);
1977 	mutex_unlock(&video_list_lock);
1978 
1979 	kfree(video->attached_array);
1980 	kfree(video);
1981 
1982 	return 0;
1983 }
1984 
1985 static int __init is_i740(struct pci_dev *dev)
1986 {
1987 	if (dev->device == 0x00D1)
1988 		return 1;
1989 	if (dev->device == 0x7000)
1990 		return 1;
1991 	return 0;
1992 }
1993 
1994 static int __init intel_opregion_present(void)
1995 {
1996 	int opregion = 0;
1997 	struct pci_dev *dev = NULL;
1998 	u32 address;
1999 
2000 	for_each_pci_dev(dev) {
2001 		if ((dev->class >> 8) != PCI_CLASS_DISPLAY_VGA)
2002 			continue;
2003 		if (dev->vendor != PCI_VENDOR_ID_INTEL)
2004 			continue;
2005 		/* We don't want to poke around undefined i740 registers */
2006 		if (is_i740(dev))
2007 			continue;
2008 		pci_read_config_dword(dev, 0xfc, &address);
2009 		if (!address)
2010 			continue;
2011 		opregion = 1;
2012 	}
2013 	return opregion;
2014 }
2015 
2016 int acpi_video_register(void)
2017 {
2018 	int ret = 0;
2019 
2020 	mutex_lock(&register_count_mutex);
2021 	if (register_count) {
2022 		/*
2023 		 * if the function of acpi_video_register is already called,
2024 		 * don't register the acpi_vide_bus again and return no error.
2025 		 */
2026 		goto leave;
2027 	}
2028 
2029 	mutex_init(&video_list_lock);
2030 	INIT_LIST_HEAD(&video_bus_head);
2031 
2032 	dmi_check_system(video_dmi_table);
2033 
2034 	ret = acpi_bus_register_driver(&acpi_video_bus);
2035 	if (ret)
2036 		goto leave;
2037 
2038 	/*
2039 	 * When the acpi_video_bus is loaded successfully, increase
2040 	 * the counter reference.
2041 	 */
2042 	register_count = 1;
2043 
2044 leave:
2045 	mutex_unlock(&register_count_mutex);
2046 	return ret;
2047 }
2048 EXPORT_SYMBOL(acpi_video_register);
2049 
2050 void acpi_video_unregister(void)
2051 {
2052 	mutex_lock(&register_count_mutex);
2053 	if (register_count) {
2054 		acpi_bus_unregister_driver(&acpi_video_bus);
2055 		register_count = 0;
2056 	}
2057 	mutex_unlock(&register_count_mutex);
2058 }
2059 EXPORT_SYMBOL(acpi_video_unregister);
2060 
2061 void acpi_video_unregister_backlight(void)
2062 {
2063 	struct acpi_video_bus *video;
2064 
2065 	mutex_lock(&register_count_mutex);
2066 	if (register_count) {
2067 		mutex_lock(&video_list_lock);
2068 		list_for_each_entry(video, &video_bus_head, entry)
2069 			acpi_video_bus_unregister_backlight(video);
2070 		mutex_unlock(&video_list_lock);
2071 	}
2072 	mutex_unlock(&register_count_mutex);
2073 }
2074 
2075 /*
2076  * This is kind of nasty. Hardware using Intel chipsets may require
2077  * the video opregion code to be run first in order to initialise
2078  * state before any ACPI video calls are made. To handle this we defer
2079  * registration of the video class until the opregion code has run.
2080  */
2081 
2082 static int __init acpi_video_init(void)
2083 {
2084 	/*
2085 	 * Let the module load even if ACPI is disabled (e.g. due to
2086 	 * a broken BIOS) so that i915.ko can still be loaded on such
2087 	 * old systems without an AcpiOpRegion.
2088 	 *
2089 	 * acpi_video_register() will report -ENODEV later as well due
2090 	 * to acpi_disabled when i915.ko tries to register itself afterwards.
2091 	 */
2092 	if (acpi_disabled)
2093 		return 0;
2094 
2095 	if (intel_opregion_present())
2096 		return 0;
2097 
2098 	return acpi_video_register();
2099 }
2100 
2101 static void __exit acpi_video_exit(void)
2102 {
2103 	acpi_video_detect_exit();
2104 	acpi_video_unregister();
2105 
2106 	return;
2107 }
2108 
2109 module_init(acpi_video_init);
2110 module_exit(acpi_video_exit);
2111