xref: /openbmc/linux/drivers/video/fbdev/udlfb.c (revision d2999e1b)
1 /*
2  * udlfb.c -- Framebuffer driver for DisplayLink USB controller
3  *
4  * Copyright (C) 2009 Roberto De Ioris <roberto@unbit.it>
5  * Copyright (C) 2009 Jaya Kumar <jayakumar.lkml@gmail.com>
6  * Copyright (C) 2009 Bernie Thompson <bernie@plugable.com>
7  *
8  * This file is subject to the terms and conditions of the GNU General Public
9  * License v2. See the file COPYING in the main directory of this archive for
10  * more details.
11  *
12  * Layout is based on skeletonfb by James Simmons and Geert Uytterhoeven,
13  * usb-skeleton by GregKH.
14  *
15  * Device-specific portions based on information from Displaylink, with work
16  * from Florian Echtler, Henrik Bjerregaard Pedersen, and others.
17  */
18 
19 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
20 
21 #include <linux/module.h>
22 #include <linux/kernel.h>
23 #include <linux/init.h>
24 #include <linux/usb.h>
25 #include <linux/uaccess.h>
26 #include <linux/mm.h>
27 #include <linux/fb.h>
28 #include <linux/vmalloc.h>
29 #include <linux/slab.h>
30 #include <linux/prefetch.h>
31 #include <linux/delay.h>
32 #include <video/udlfb.h>
33 #include "edid.h"
34 
35 static struct fb_fix_screeninfo dlfb_fix = {
36 	.id =           "udlfb",
37 	.type =         FB_TYPE_PACKED_PIXELS,
38 	.visual =       FB_VISUAL_TRUECOLOR,
39 	.xpanstep =     0,
40 	.ypanstep =     0,
41 	.ywrapstep =    0,
42 	.accel =        FB_ACCEL_NONE,
43 };
44 
45 static const u32 udlfb_info_flags = FBINFO_DEFAULT | FBINFO_READS_FAST |
46 		FBINFO_VIRTFB |
47 		FBINFO_HWACCEL_IMAGEBLIT | FBINFO_HWACCEL_FILLRECT |
48 		FBINFO_HWACCEL_COPYAREA | FBINFO_MISC_ALWAYS_SETPAR;
49 
50 /*
51  * There are many DisplayLink-based graphics products, all with unique PIDs.
52  * So we match on DisplayLink's VID + Vendor-Defined Interface Class (0xff)
53  * We also require a match on SubClass (0x00) and Protocol (0x00),
54  * which is compatible with all known USB 2.0 era graphics chips and firmware,
55  * but allows DisplayLink to increment those for any future incompatible chips
56  */
57 static struct usb_device_id id_table[] = {
58 	{.idVendor = 0x17e9,
59 	 .bInterfaceClass = 0xff,
60 	 .bInterfaceSubClass = 0x00,
61 	 .bInterfaceProtocol = 0x00,
62 	 .match_flags = USB_DEVICE_ID_MATCH_VENDOR |
63 		USB_DEVICE_ID_MATCH_INT_CLASS |
64 		USB_DEVICE_ID_MATCH_INT_SUBCLASS |
65 		USB_DEVICE_ID_MATCH_INT_PROTOCOL,
66 	},
67 	{},
68 };
69 MODULE_DEVICE_TABLE(usb, id_table);
70 
71 /* module options */
72 static bool console = 1; /* Allow fbcon to open framebuffer */
73 static bool fb_defio = 1;  /* Detect mmap writes using page faults */
74 static bool shadow = 1; /* Optionally disable shadow framebuffer */
75 static int pixel_limit; /* Optionally force a pixel resolution limit */
76 
77 /* dlfb keeps a list of urbs for efficient bulk transfers */
78 static void dlfb_urb_completion(struct urb *urb);
79 static struct urb *dlfb_get_urb(struct dlfb_data *dev);
80 static int dlfb_submit_urb(struct dlfb_data *dev, struct urb * urb, size_t len);
81 static int dlfb_alloc_urb_list(struct dlfb_data *dev, int count, size_t size);
82 static void dlfb_free_urb_list(struct dlfb_data *dev);
83 
84 /*
85  * All DisplayLink bulk operations start with 0xAF, followed by specific code
86  * All operations are written to buffers which then later get sent to device
87  */
88 static char *dlfb_set_register(char *buf, u8 reg, u8 val)
89 {
90 	*buf++ = 0xAF;
91 	*buf++ = 0x20;
92 	*buf++ = reg;
93 	*buf++ = val;
94 	return buf;
95 }
96 
97 static char *dlfb_vidreg_lock(char *buf)
98 {
99 	return dlfb_set_register(buf, 0xFF, 0x00);
100 }
101 
102 static char *dlfb_vidreg_unlock(char *buf)
103 {
104 	return dlfb_set_register(buf, 0xFF, 0xFF);
105 }
106 
107 /*
108  * Map FB_BLANK_* to DisplayLink register
109  * DLReg FB_BLANK_*
110  * ----- -----------------------------
111  *  0x00 FB_BLANK_UNBLANK (0)
112  *  0x01 FB_BLANK (1)
113  *  0x03 FB_BLANK_VSYNC_SUSPEND (2)
114  *  0x05 FB_BLANK_HSYNC_SUSPEND (3)
115  *  0x07 FB_BLANK_POWERDOWN (4) Note: requires modeset to come back
116  */
117 static char *dlfb_blanking(char *buf, int fb_blank)
118 {
119 	u8 reg;
120 
121 	switch (fb_blank) {
122 	case FB_BLANK_POWERDOWN:
123 		reg = 0x07;
124 		break;
125 	case FB_BLANK_HSYNC_SUSPEND:
126 		reg = 0x05;
127 		break;
128 	case FB_BLANK_VSYNC_SUSPEND:
129 		reg = 0x03;
130 		break;
131 	case FB_BLANK_NORMAL:
132 		reg = 0x01;
133 		break;
134 	default:
135 		reg = 0x00;
136 	}
137 
138 	buf = dlfb_set_register(buf, 0x1F, reg);
139 
140 	return buf;
141 }
142 
143 static char *dlfb_set_color_depth(char *buf, u8 selection)
144 {
145 	return dlfb_set_register(buf, 0x00, selection);
146 }
147 
148 static char *dlfb_set_base16bpp(char *wrptr, u32 base)
149 {
150 	/* the base pointer is 16 bits wide, 0x20 is hi byte. */
151 	wrptr = dlfb_set_register(wrptr, 0x20, base >> 16);
152 	wrptr = dlfb_set_register(wrptr, 0x21, base >> 8);
153 	return dlfb_set_register(wrptr, 0x22, base);
154 }
155 
156 /*
157  * DisplayLink HW has separate 16bpp and 8bpp framebuffers.
158  * In 24bpp modes, the low 323 RGB bits go in the 8bpp framebuffer
159  */
160 static char *dlfb_set_base8bpp(char *wrptr, u32 base)
161 {
162 	wrptr = dlfb_set_register(wrptr, 0x26, base >> 16);
163 	wrptr = dlfb_set_register(wrptr, 0x27, base >> 8);
164 	return dlfb_set_register(wrptr, 0x28, base);
165 }
166 
167 static char *dlfb_set_register_16(char *wrptr, u8 reg, u16 value)
168 {
169 	wrptr = dlfb_set_register(wrptr, reg, value >> 8);
170 	return dlfb_set_register(wrptr, reg+1, value);
171 }
172 
173 /*
174  * This is kind of weird because the controller takes some
175  * register values in a different byte order than other registers.
176  */
177 static char *dlfb_set_register_16be(char *wrptr, u8 reg, u16 value)
178 {
179 	wrptr = dlfb_set_register(wrptr, reg, value);
180 	return dlfb_set_register(wrptr, reg+1, value >> 8);
181 }
182 
183 /*
184  * LFSR is linear feedback shift register. The reason we have this is
185  * because the display controller needs to minimize the clock depth of
186  * various counters used in the display path. So this code reverses the
187  * provided value into the lfsr16 value by counting backwards to get
188  * the value that needs to be set in the hardware comparator to get the
189  * same actual count. This makes sense once you read above a couple of
190  * times and think about it from a hardware perspective.
191  */
192 static u16 dlfb_lfsr16(u16 actual_count)
193 {
194 	u32 lv = 0xFFFF; /* This is the lfsr value that the hw starts with */
195 
196 	while (actual_count--) {
197 		lv =	 ((lv << 1) |
198 			(((lv >> 15) ^ (lv >> 4) ^ (lv >> 2) ^ (lv >> 1)) & 1))
199 			& 0xFFFF;
200 	}
201 
202 	return (u16) lv;
203 }
204 
205 /*
206  * This does LFSR conversion on the value that is to be written.
207  * See LFSR explanation above for more detail.
208  */
209 static char *dlfb_set_register_lfsr16(char *wrptr, u8 reg, u16 value)
210 {
211 	return dlfb_set_register_16(wrptr, reg, dlfb_lfsr16(value));
212 }
213 
214 /*
215  * This takes a standard fbdev screeninfo struct and all of its monitor mode
216  * details and converts them into the DisplayLink equivalent register commands.
217  */
218 static char *dlfb_set_vid_cmds(char *wrptr, struct fb_var_screeninfo *var)
219 {
220 	u16 xds, yds;
221 	u16 xde, yde;
222 	u16 yec;
223 
224 	/* x display start */
225 	xds = var->left_margin + var->hsync_len;
226 	wrptr = dlfb_set_register_lfsr16(wrptr, 0x01, xds);
227 	/* x display end */
228 	xde = xds + var->xres;
229 	wrptr = dlfb_set_register_lfsr16(wrptr, 0x03, xde);
230 
231 	/* y display start */
232 	yds = var->upper_margin + var->vsync_len;
233 	wrptr = dlfb_set_register_lfsr16(wrptr, 0x05, yds);
234 	/* y display end */
235 	yde = yds + var->yres;
236 	wrptr = dlfb_set_register_lfsr16(wrptr, 0x07, yde);
237 
238 	/* x end count is active + blanking - 1 */
239 	wrptr = dlfb_set_register_lfsr16(wrptr, 0x09,
240 			xde + var->right_margin - 1);
241 
242 	/* libdlo hardcodes hsync start to 1 */
243 	wrptr = dlfb_set_register_lfsr16(wrptr, 0x0B, 1);
244 
245 	/* hsync end is width of sync pulse + 1 */
246 	wrptr = dlfb_set_register_lfsr16(wrptr, 0x0D, var->hsync_len + 1);
247 
248 	/* hpixels is active pixels */
249 	wrptr = dlfb_set_register_16(wrptr, 0x0F, var->xres);
250 
251 	/* yendcount is vertical active + vertical blanking */
252 	yec = var->yres + var->upper_margin + var->lower_margin +
253 			var->vsync_len;
254 	wrptr = dlfb_set_register_lfsr16(wrptr, 0x11, yec);
255 
256 	/* libdlo hardcodes vsync start to 0 */
257 	wrptr = dlfb_set_register_lfsr16(wrptr, 0x13, 0);
258 
259 	/* vsync end is width of vsync pulse */
260 	wrptr = dlfb_set_register_lfsr16(wrptr, 0x15, var->vsync_len);
261 
262 	/* vpixels is active pixels */
263 	wrptr = dlfb_set_register_16(wrptr, 0x17, var->yres);
264 
265 	/* convert picoseconds to 5kHz multiple for pclk5k = x * 1E12/5k */
266 	wrptr = dlfb_set_register_16be(wrptr, 0x1B,
267 			200*1000*1000/var->pixclock);
268 
269 	return wrptr;
270 }
271 
272 /*
273  * This takes a standard fbdev screeninfo struct that was fetched or prepared
274  * and then generates the appropriate command sequence that then drives the
275  * display controller.
276  */
277 static int dlfb_set_video_mode(struct dlfb_data *dev,
278 				struct fb_var_screeninfo *var)
279 {
280 	char *buf;
281 	char *wrptr;
282 	int retval = 0;
283 	int writesize;
284 	struct urb *urb;
285 
286 	if (!atomic_read(&dev->usb_active))
287 		return -EPERM;
288 
289 	urb = dlfb_get_urb(dev);
290 	if (!urb)
291 		return -ENOMEM;
292 
293 	buf = (char *) urb->transfer_buffer;
294 
295 	/*
296 	* This first section has to do with setting the base address on the
297 	* controller * associated with the display. There are 2 base
298 	* pointers, currently, we only * use the 16 bpp segment.
299 	*/
300 	wrptr = dlfb_vidreg_lock(buf);
301 	wrptr = dlfb_set_color_depth(wrptr, 0x00);
302 	/* set base for 16bpp segment to 0 */
303 	wrptr = dlfb_set_base16bpp(wrptr, 0);
304 	/* set base for 8bpp segment to end of fb */
305 	wrptr = dlfb_set_base8bpp(wrptr, dev->info->fix.smem_len);
306 
307 	wrptr = dlfb_set_vid_cmds(wrptr, var);
308 	wrptr = dlfb_blanking(wrptr, FB_BLANK_UNBLANK);
309 	wrptr = dlfb_vidreg_unlock(wrptr);
310 
311 	writesize = wrptr - buf;
312 
313 	retval = dlfb_submit_urb(dev, urb, writesize);
314 
315 	dev->blank_mode = FB_BLANK_UNBLANK;
316 
317 	return retval;
318 }
319 
320 static int dlfb_ops_mmap(struct fb_info *info, struct vm_area_struct *vma)
321 {
322 	unsigned long start = vma->vm_start;
323 	unsigned long size = vma->vm_end - vma->vm_start;
324 	unsigned long offset = vma->vm_pgoff << PAGE_SHIFT;
325 	unsigned long page, pos;
326 
327 	if (vma->vm_pgoff > (~0UL >> PAGE_SHIFT))
328 		return -EINVAL;
329 	if (size > info->fix.smem_len)
330 		return -EINVAL;
331 	if (offset > info->fix.smem_len - size)
332 		return -EINVAL;
333 
334 	pos = (unsigned long)info->fix.smem_start + offset;
335 
336 	pr_notice("mmap() framebuffer addr:%lu size:%lu\n",
337 		  pos, size);
338 
339 	while (size > 0) {
340 		page = vmalloc_to_pfn((void *)pos);
341 		if (remap_pfn_range(vma, start, page, PAGE_SIZE, PAGE_SHARED))
342 			return -EAGAIN;
343 
344 		start += PAGE_SIZE;
345 		pos += PAGE_SIZE;
346 		if (size > PAGE_SIZE)
347 			size -= PAGE_SIZE;
348 		else
349 			size = 0;
350 	}
351 
352 	return 0;
353 }
354 
355 /*
356  * Trims identical data from front and back of line
357  * Sets new front buffer address and width
358  * And returns byte count of identical pixels
359  * Assumes CPU natural alignment (unsigned long)
360  * for back and front buffer ptrs and width
361  */
362 static int dlfb_trim_hline(const u8 *bback, const u8 **bfront, int *width_bytes)
363 {
364 	int j, k;
365 	const unsigned long *back = (const unsigned long *) bback;
366 	const unsigned long *front = (const unsigned long *) *bfront;
367 	const int width = *width_bytes / sizeof(unsigned long);
368 	int identical = width;
369 	int start = width;
370 	int end = width;
371 
372 	prefetch((void *) front);
373 	prefetch((void *) back);
374 
375 	for (j = 0; j < width; j++) {
376 		if (back[j] != front[j]) {
377 			start = j;
378 			break;
379 		}
380 	}
381 
382 	for (k = width - 1; k > j; k--) {
383 		if (back[k] != front[k]) {
384 			end = k+1;
385 			break;
386 		}
387 	}
388 
389 	identical = start + (width - end);
390 	*bfront = (u8 *) &front[start];
391 	*width_bytes = (end - start) * sizeof(unsigned long);
392 
393 	return identical * sizeof(unsigned long);
394 }
395 
396 /*
397  * Render a command stream for an encoded horizontal line segment of pixels.
398  *
399  * A command buffer holds several commands.
400  * It always begins with a fresh command header
401  * (the protocol doesn't require this, but we enforce it to allow
402  * multiple buffers to be potentially encoded and sent in parallel).
403  * A single command encodes one contiguous horizontal line of pixels
404  *
405  * The function relies on the client to do all allocation, so that
406  * rendering can be done directly to output buffers (e.g. USB URBs).
407  * The function fills the supplied command buffer, providing information
408  * on where it left off, so the client may call in again with additional
409  * buffers if the line will take several buffers to complete.
410  *
411  * A single command can transmit a maximum of 256 pixels,
412  * regardless of the compression ratio (protocol design limit).
413  * To the hardware, 0 for a size byte means 256
414  *
415  * Rather than 256 pixel commands which are either rl or raw encoded,
416  * the rlx command simply assumes alternating raw and rl spans within one cmd.
417  * This has a slightly larger header overhead, but produces more even results.
418  * It also processes all data (read and write) in a single pass.
419  * Performance benchmarks of common cases show it having just slightly better
420  * compression than 256 pixel raw or rle commands, with similar CPU consumpion.
421  * But for very rl friendly data, will compress not quite as well.
422  */
423 static void dlfb_compress_hline(
424 	const uint16_t **pixel_start_ptr,
425 	const uint16_t *const pixel_end,
426 	uint32_t *device_address_ptr,
427 	uint8_t **command_buffer_ptr,
428 	const uint8_t *const cmd_buffer_end)
429 {
430 	const uint16_t *pixel = *pixel_start_ptr;
431 	uint32_t dev_addr  = *device_address_ptr;
432 	uint8_t *cmd = *command_buffer_ptr;
433 	const int bpp = 2;
434 
435 	while ((pixel_end > pixel) &&
436 	       (cmd_buffer_end - MIN_RLX_CMD_BYTES > cmd)) {
437 		uint8_t *raw_pixels_count_byte = NULL;
438 		uint8_t *cmd_pixels_count_byte = NULL;
439 		const uint16_t *raw_pixel_start = NULL;
440 		const uint16_t *cmd_pixel_start, *cmd_pixel_end = NULL;
441 
442 		prefetchw((void *) cmd); /* pull in one cache line at least */
443 
444 		*cmd++ = 0xAF;
445 		*cmd++ = 0x6B;
446 		*cmd++ = (uint8_t) ((dev_addr >> 16) & 0xFF);
447 		*cmd++ = (uint8_t) ((dev_addr >> 8) & 0xFF);
448 		*cmd++ = (uint8_t) ((dev_addr) & 0xFF);
449 
450 		cmd_pixels_count_byte = cmd++; /*  we'll know this later */
451 		cmd_pixel_start = pixel;
452 
453 		raw_pixels_count_byte = cmd++; /*  we'll know this later */
454 		raw_pixel_start = pixel;
455 
456 		cmd_pixel_end = pixel + min(MAX_CMD_PIXELS + 1,
457 			min((int)(pixel_end - pixel),
458 			    (int)(cmd_buffer_end - cmd) / bpp));
459 
460 		prefetch_range((void *) pixel, (cmd_pixel_end - pixel) * bpp);
461 
462 		while (pixel < cmd_pixel_end) {
463 			const uint16_t * const repeating_pixel = pixel;
464 
465 			*(uint16_t *)cmd = cpu_to_be16p(pixel);
466 			cmd += 2;
467 			pixel++;
468 
469 			if (unlikely((pixel < cmd_pixel_end) &&
470 				     (*pixel == *repeating_pixel))) {
471 				/* go back and fill in raw pixel count */
472 				*raw_pixels_count_byte = ((repeating_pixel -
473 						raw_pixel_start) + 1) & 0xFF;
474 
475 				while ((pixel < cmd_pixel_end)
476 				       && (*pixel == *repeating_pixel)) {
477 					pixel++;
478 				}
479 
480 				/* immediately after raw data is repeat byte */
481 				*cmd++ = ((pixel - repeating_pixel) - 1) & 0xFF;
482 
483 				/* Then start another raw pixel span */
484 				raw_pixel_start = pixel;
485 				raw_pixels_count_byte = cmd++;
486 			}
487 		}
488 
489 		if (pixel > raw_pixel_start) {
490 			/* finalize last RAW span */
491 			*raw_pixels_count_byte = (pixel-raw_pixel_start) & 0xFF;
492 		}
493 
494 		*cmd_pixels_count_byte = (pixel - cmd_pixel_start) & 0xFF;
495 		dev_addr += (pixel - cmd_pixel_start) * bpp;
496 	}
497 
498 	if (cmd_buffer_end <= MIN_RLX_CMD_BYTES + cmd) {
499 		/* Fill leftover bytes with no-ops */
500 		if (cmd_buffer_end > cmd)
501 			memset(cmd, 0xAF, cmd_buffer_end - cmd);
502 		cmd = (uint8_t *) cmd_buffer_end;
503 	}
504 
505 	*command_buffer_ptr = cmd;
506 	*pixel_start_ptr = pixel;
507 	*device_address_ptr = dev_addr;
508 
509 	return;
510 }
511 
512 /*
513  * There are 3 copies of every pixel: The front buffer that the fbdev
514  * client renders to, the actual framebuffer across the USB bus in hardware
515  * (that we can only write to, slowly, and can never read), and (optionally)
516  * our shadow copy that tracks what's been sent to that hardware buffer.
517  */
518 static int dlfb_render_hline(struct dlfb_data *dev, struct urb **urb_ptr,
519 			      const char *front, char **urb_buf_ptr,
520 			      u32 byte_offset, u32 byte_width,
521 			      int *ident_ptr, int *sent_ptr)
522 {
523 	const u8 *line_start, *line_end, *next_pixel;
524 	u32 dev_addr = dev->base16 + byte_offset;
525 	struct urb *urb = *urb_ptr;
526 	u8 *cmd = *urb_buf_ptr;
527 	u8 *cmd_end = (u8 *) urb->transfer_buffer + urb->transfer_buffer_length;
528 
529 	line_start = (u8 *) (front + byte_offset);
530 	next_pixel = line_start;
531 	line_end = next_pixel + byte_width;
532 
533 	if (dev->backing_buffer) {
534 		int offset;
535 		const u8 *back_start = (u8 *) (dev->backing_buffer
536 						+ byte_offset);
537 
538 		*ident_ptr += dlfb_trim_hline(back_start, &next_pixel,
539 			&byte_width);
540 
541 		offset = next_pixel - line_start;
542 		line_end = next_pixel + byte_width;
543 		dev_addr += offset;
544 		back_start += offset;
545 		line_start += offset;
546 
547 		memcpy((char *)back_start, (char *) line_start,
548 		       byte_width);
549 	}
550 
551 	while (next_pixel < line_end) {
552 
553 		dlfb_compress_hline((const uint16_t **) &next_pixel,
554 			     (const uint16_t *) line_end, &dev_addr,
555 			(u8 **) &cmd, (u8 *) cmd_end);
556 
557 		if (cmd >= cmd_end) {
558 			int len = cmd - (u8 *) urb->transfer_buffer;
559 			if (dlfb_submit_urb(dev, urb, len))
560 				return 1; /* lost pixels is set */
561 			*sent_ptr += len;
562 			urb = dlfb_get_urb(dev);
563 			if (!urb)
564 				return 1; /* lost_pixels is set */
565 			*urb_ptr = urb;
566 			cmd = urb->transfer_buffer;
567 			cmd_end = &cmd[urb->transfer_buffer_length];
568 		}
569 	}
570 
571 	*urb_buf_ptr = cmd;
572 
573 	return 0;
574 }
575 
576 static int dlfb_handle_damage(struct dlfb_data *dev, int x, int y,
577 	       int width, int height, char *data)
578 {
579 	int i, ret;
580 	char *cmd;
581 	cycles_t start_cycles, end_cycles;
582 	int bytes_sent = 0;
583 	int bytes_identical = 0;
584 	struct urb *urb;
585 	int aligned_x;
586 
587 	start_cycles = get_cycles();
588 
589 	aligned_x = DL_ALIGN_DOWN(x, sizeof(unsigned long));
590 	width = DL_ALIGN_UP(width + (x-aligned_x), sizeof(unsigned long));
591 	x = aligned_x;
592 
593 	if ((width <= 0) ||
594 	    (x + width > dev->info->var.xres) ||
595 	    (y + height > dev->info->var.yres))
596 		return -EINVAL;
597 
598 	if (!atomic_read(&dev->usb_active))
599 		return 0;
600 
601 	urb = dlfb_get_urb(dev);
602 	if (!urb)
603 		return 0;
604 	cmd = urb->transfer_buffer;
605 
606 	for (i = y; i < y + height ; i++) {
607 		const int line_offset = dev->info->fix.line_length * i;
608 		const int byte_offset = line_offset + (x * BPP);
609 
610 		if (dlfb_render_hline(dev, &urb,
611 				      (char *) dev->info->fix.smem_start,
612 				      &cmd, byte_offset, width * BPP,
613 				      &bytes_identical, &bytes_sent))
614 			goto error;
615 	}
616 
617 	if (cmd > (char *) urb->transfer_buffer) {
618 		/* Send partial buffer remaining before exiting */
619 		int len = cmd - (char *) urb->transfer_buffer;
620 		ret = dlfb_submit_urb(dev, urb, len);
621 		bytes_sent += len;
622 	} else
623 		dlfb_urb_completion(urb);
624 
625 error:
626 	atomic_add(bytes_sent, &dev->bytes_sent);
627 	atomic_add(bytes_identical, &dev->bytes_identical);
628 	atomic_add(width*height*2, &dev->bytes_rendered);
629 	end_cycles = get_cycles();
630 	atomic_add(((unsigned int) ((end_cycles - start_cycles)
631 		    >> 10)), /* Kcycles */
632 		   &dev->cpu_kcycles_used);
633 
634 	return 0;
635 }
636 
637 /*
638  * Path triggered by usermode clients who write to filesystem
639  * e.g. cat filename > /dev/fb1
640  * Not used by X Windows or text-mode console. But useful for testing.
641  * Slow because of extra copy and we must assume all pixels dirty.
642  */
643 static ssize_t dlfb_ops_write(struct fb_info *info, const char __user *buf,
644 			  size_t count, loff_t *ppos)
645 {
646 	ssize_t result;
647 	struct dlfb_data *dev = info->par;
648 	u32 offset = (u32) *ppos;
649 
650 	result = fb_sys_write(info, buf, count, ppos);
651 
652 	if (result > 0) {
653 		int start = max((int)(offset / info->fix.line_length), 0);
654 		int lines = min((u32)((result / info->fix.line_length) + 1),
655 				(u32)info->var.yres);
656 
657 		dlfb_handle_damage(dev, 0, start, info->var.xres,
658 			lines, info->screen_base);
659 	}
660 
661 	return result;
662 }
663 
664 /* hardware has native COPY command (see libdlo), but not worth it for fbcon */
665 static void dlfb_ops_copyarea(struct fb_info *info,
666 				const struct fb_copyarea *area)
667 {
668 
669 	struct dlfb_data *dev = info->par;
670 
671 	sys_copyarea(info, area);
672 
673 	dlfb_handle_damage(dev, area->dx, area->dy,
674 			area->width, area->height, info->screen_base);
675 }
676 
677 static void dlfb_ops_imageblit(struct fb_info *info,
678 				const struct fb_image *image)
679 {
680 	struct dlfb_data *dev = info->par;
681 
682 	sys_imageblit(info, image);
683 
684 	dlfb_handle_damage(dev, image->dx, image->dy,
685 			image->width, image->height, info->screen_base);
686 }
687 
688 static void dlfb_ops_fillrect(struct fb_info *info,
689 			  const struct fb_fillrect *rect)
690 {
691 	struct dlfb_data *dev = info->par;
692 
693 	sys_fillrect(info, rect);
694 
695 	dlfb_handle_damage(dev, rect->dx, rect->dy, rect->width,
696 			      rect->height, info->screen_base);
697 }
698 
699 /*
700  * NOTE: fb_defio.c is holding info->fbdefio.mutex
701  *   Touching ANY framebuffer memory that triggers a page fault
702  *   in fb_defio will cause a deadlock, when it also tries to
703  *   grab the same mutex.
704  */
705 static void dlfb_dpy_deferred_io(struct fb_info *info,
706 				struct list_head *pagelist)
707 {
708 	struct page *cur;
709 	struct fb_deferred_io *fbdefio = info->fbdefio;
710 	struct dlfb_data *dev = info->par;
711 	struct urb *urb;
712 	char *cmd;
713 	cycles_t start_cycles, end_cycles;
714 	int bytes_sent = 0;
715 	int bytes_identical = 0;
716 	int bytes_rendered = 0;
717 
718 	if (!fb_defio)
719 		return;
720 
721 	if (!atomic_read(&dev->usb_active))
722 		return;
723 
724 	start_cycles = get_cycles();
725 
726 	urb = dlfb_get_urb(dev);
727 	if (!urb)
728 		return;
729 
730 	cmd = urb->transfer_buffer;
731 
732 	/* walk the written page list and render each to device */
733 	list_for_each_entry(cur, &fbdefio->pagelist, lru) {
734 
735 		if (dlfb_render_hline(dev, &urb, (char *) info->fix.smem_start,
736 				  &cmd, cur->index << PAGE_SHIFT,
737 				  PAGE_SIZE, &bytes_identical, &bytes_sent))
738 			goto error;
739 		bytes_rendered += PAGE_SIZE;
740 	}
741 
742 	if (cmd > (char *) urb->transfer_buffer) {
743 		/* Send partial buffer remaining before exiting */
744 		int len = cmd - (char *) urb->transfer_buffer;
745 		dlfb_submit_urb(dev, urb, len);
746 		bytes_sent += len;
747 	} else
748 		dlfb_urb_completion(urb);
749 
750 error:
751 	atomic_add(bytes_sent, &dev->bytes_sent);
752 	atomic_add(bytes_identical, &dev->bytes_identical);
753 	atomic_add(bytes_rendered, &dev->bytes_rendered);
754 	end_cycles = get_cycles();
755 	atomic_add(((unsigned int) ((end_cycles - start_cycles)
756 		    >> 10)), /* Kcycles */
757 		   &dev->cpu_kcycles_used);
758 }
759 
760 static int dlfb_get_edid(struct dlfb_data *dev, char *edid, int len)
761 {
762 	int i;
763 	int ret;
764 	char *rbuf;
765 
766 	rbuf = kmalloc(2, GFP_KERNEL);
767 	if (!rbuf)
768 		return 0;
769 
770 	for (i = 0; i < len; i++) {
771 		ret = usb_control_msg(dev->udev,
772 				    usb_rcvctrlpipe(dev->udev, 0), (0x02),
773 				    (0x80 | (0x02 << 5)), i << 8, 0xA1, rbuf, 2,
774 				    HZ);
775 		if (ret < 1) {
776 			pr_err("Read EDID byte %d failed err %x\n", i, ret);
777 			i--;
778 			break;
779 		}
780 		edid[i] = rbuf[1];
781 	}
782 
783 	kfree(rbuf);
784 
785 	return i;
786 }
787 
788 static int dlfb_ops_ioctl(struct fb_info *info, unsigned int cmd,
789 				unsigned long arg)
790 {
791 
792 	struct dlfb_data *dev = info->par;
793 
794 	if (!atomic_read(&dev->usb_active))
795 		return 0;
796 
797 	/* TODO: Update X server to get this from sysfs instead */
798 	if (cmd == DLFB_IOCTL_RETURN_EDID) {
799 		void __user *edid = (void __user *)arg;
800 		if (copy_to_user(edid, dev->edid, dev->edid_size))
801 			return -EFAULT;
802 		return 0;
803 	}
804 
805 	/* TODO: Help propose a standard fb.h ioctl to report mmap damage */
806 	if (cmd == DLFB_IOCTL_REPORT_DAMAGE) {
807 		struct dloarea area;
808 
809 		if (copy_from_user(&area, (void __user *)arg,
810 				  sizeof(struct dloarea)))
811 			return -EFAULT;
812 
813 		/*
814 		 * If we have a damage-aware client, turn fb_defio "off"
815 		 * To avoid perf imact of unnecessary page fault handling.
816 		 * Done by resetting the delay for this fb_info to a very
817 		 * long period. Pages will become writable and stay that way.
818 		 * Reset to normal value when all clients have closed this fb.
819 		 */
820 		if (info->fbdefio)
821 			info->fbdefio->delay = DL_DEFIO_WRITE_DISABLE;
822 
823 		if (area.x < 0)
824 			area.x = 0;
825 
826 		if (area.x > info->var.xres)
827 			area.x = info->var.xres;
828 
829 		if (area.y < 0)
830 			area.y = 0;
831 
832 		if (area.y > info->var.yres)
833 			area.y = info->var.yres;
834 
835 		dlfb_handle_damage(dev, area.x, area.y, area.w, area.h,
836 			   info->screen_base);
837 	}
838 
839 	return 0;
840 }
841 
842 /* taken from vesafb */
843 static int
844 dlfb_ops_setcolreg(unsigned regno, unsigned red, unsigned green,
845 	       unsigned blue, unsigned transp, struct fb_info *info)
846 {
847 	int err = 0;
848 
849 	if (regno >= info->cmap.len)
850 		return 1;
851 
852 	if (regno < 16) {
853 		if (info->var.red.offset == 10) {
854 			/* 1:5:5:5 */
855 			((u32 *) (info->pseudo_palette))[regno] =
856 			    ((red & 0xf800) >> 1) |
857 			    ((green & 0xf800) >> 6) | ((blue & 0xf800) >> 11);
858 		} else {
859 			/* 0:5:6:5 */
860 			((u32 *) (info->pseudo_palette))[regno] =
861 			    ((red & 0xf800)) |
862 			    ((green & 0xfc00) >> 5) | ((blue & 0xf800) >> 11);
863 		}
864 	}
865 
866 	return err;
867 }
868 
869 /*
870  * It's common for several clients to have framebuffer open simultaneously.
871  * e.g. both fbcon and X. Makes things interesting.
872  * Assumes caller is holding info->lock (for open and release at least)
873  */
874 static int dlfb_ops_open(struct fb_info *info, int user)
875 {
876 	struct dlfb_data *dev = info->par;
877 
878 	/*
879 	 * fbcon aggressively connects to first framebuffer it finds,
880 	 * preventing other clients (X) from working properly. Usually
881 	 * not what the user wants. Fail by default with option to enable.
882 	 */
883 	if ((user == 0) && (!console))
884 		return -EBUSY;
885 
886 	/* If the USB device is gone, we don't accept new opens */
887 	if (dev->virtualized)
888 		return -ENODEV;
889 
890 	dev->fb_count++;
891 
892 	kref_get(&dev->kref);
893 
894 	if (fb_defio && (info->fbdefio == NULL)) {
895 		/* enable defio at last moment if not disabled by client */
896 
897 		struct fb_deferred_io *fbdefio;
898 
899 		fbdefio = kzalloc(sizeof(struct fb_deferred_io), GFP_KERNEL);
900 
901 		if (fbdefio) {
902 			fbdefio->delay = DL_DEFIO_WRITE_DELAY;
903 			fbdefio->deferred_io = dlfb_dpy_deferred_io;
904 		}
905 
906 		info->fbdefio = fbdefio;
907 		fb_deferred_io_init(info);
908 	}
909 
910 	pr_notice("open /dev/fb%d user=%d fb_info=%p count=%d\n",
911 	    info->node, user, info, dev->fb_count);
912 
913 	return 0;
914 }
915 
916 /*
917  * Called when all client interfaces to start transactions have been disabled,
918  * and all references to our device instance (dlfb_data) are released.
919  * Every transaction must have a reference, so we know are fully spun down
920  */
921 static void dlfb_free(struct kref *kref)
922 {
923 	struct dlfb_data *dev = container_of(kref, struct dlfb_data, kref);
924 
925 	if (dev->backing_buffer)
926 		vfree(dev->backing_buffer);
927 
928 	kfree(dev->edid);
929 
930 	pr_warn("freeing dlfb_data %p\n", dev);
931 
932 	kfree(dev);
933 }
934 
935 static void dlfb_release_urb_work(struct work_struct *work)
936 {
937 	struct urb_node *unode = container_of(work, struct urb_node,
938 					      release_urb_work.work);
939 
940 	up(&unode->dev->urbs.limit_sem);
941 }
942 
943 static void dlfb_free_framebuffer(struct dlfb_data *dev)
944 {
945 	struct fb_info *info = dev->info;
946 
947 	if (info) {
948 		int node = info->node;
949 
950 		unregister_framebuffer(info);
951 
952 		if (info->cmap.len != 0)
953 			fb_dealloc_cmap(&info->cmap);
954 		if (info->monspecs.modedb)
955 			fb_destroy_modedb(info->monspecs.modedb);
956 		if (info->screen_base)
957 			vfree(info->screen_base);
958 
959 		fb_destroy_modelist(&info->modelist);
960 
961 		dev->info = NULL;
962 
963 		/* Assume info structure is freed after this point */
964 		framebuffer_release(info);
965 
966 		pr_warn("fb_info for /dev/fb%d has been freed\n", node);
967 	}
968 
969 	/* ref taken in probe() as part of registering framebfufer */
970 	kref_put(&dev->kref, dlfb_free);
971 }
972 
973 static void dlfb_free_framebuffer_work(struct work_struct *work)
974 {
975 	struct dlfb_data *dev = container_of(work, struct dlfb_data,
976 					     free_framebuffer_work.work);
977 	dlfb_free_framebuffer(dev);
978 }
979 /*
980  * Assumes caller is holding info->lock mutex (for open and release at least)
981  */
982 static int dlfb_ops_release(struct fb_info *info, int user)
983 {
984 	struct dlfb_data *dev = info->par;
985 
986 	dev->fb_count--;
987 
988 	/* We can't free fb_info here - fbmem will touch it when we return */
989 	if (dev->virtualized && (dev->fb_count == 0))
990 		schedule_delayed_work(&dev->free_framebuffer_work, HZ);
991 
992 	if ((dev->fb_count == 0) && (info->fbdefio)) {
993 		fb_deferred_io_cleanup(info);
994 		kfree(info->fbdefio);
995 		info->fbdefio = NULL;
996 		info->fbops->fb_mmap = dlfb_ops_mmap;
997 	}
998 
999 	pr_warn("released /dev/fb%d user=%d count=%d\n",
1000 		  info->node, user, dev->fb_count);
1001 
1002 	kref_put(&dev->kref, dlfb_free);
1003 
1004 	return 0;
1005 }
1006 
1007 /*
1008  * Check whether a video mode is supported by the DisplayLink chip
1009  * We start from monitor's modes, so don't need to filter that here
1010  */
1011 static int dlfb_is_valid_mode(struct fb_videomode *mode,
1012 		struct fb_info *info)
1013 {
1014 	struct dlfb_data *dev = info->par;
1015 
1016 	if (mode->xres * mode->yres > dev->sku_pixel_limit) {
1017 		pr_warn("%dx%d beyond chip capabilities\n",
1018 		       mode->xres, mode->yres);
1019 		return 0;
1020 	}
1021 
1022 	pr_info("%dx%d @ %d Hz valid mode\n", mode->xres, mode->yres,
1023 		mode->refresh);
1024 
1025 	return 1;
1026 }
1027 
1028 static void dlfb_var_color_format(struct fb_var_screeninfo *var)
1029 {
1030 	const struct fb_bitfield red = { 11, 5, 0 };
1031 	const struct fb_bitfield green = { 5, 6, 0 };
1032 	const struct fb_bitfield blue = { 0, 5, 0 };
1033 
1034 	var->bits_per_pixel = 16;
1035 	var->red = red;
1036 	var->green = green;
1037 	var->blue = blue;
1038 }
1039 
1040 static int dlfb_ops_check_var(struct fb_var_screeninfo *var,
1041 				struct fb_info *info)
1042 {
1043 	struct fb_videomode mode;
1044 
1045 	/* TODO: support dynamically changing framebuffer size */
1046 	if ((var->xres * var->yres * 2) > info->fix.smem_len)
1047 		return -EINVAL;
1048 
1049 	/* set device-specific elements of var unrelated to mode */
1050 	dlfb_var_color_format(var);
1051 
1052 	fb_var_to_videomode(&mode, var);
1053 
1054 	if (!dlfb_is_valid_mode(&mode, info))
1055 		return -EINVAL;
1056 
1057 	return 0;
1058 }
1059 
1060 static int dlfb_ops_set_par(struct fb_info *info)
1061 {
1062 	struct dlfb_data *dev = info->par;
1063 	int result;
1064 	u16 *pix_framebuffer;
1065 	int i;
1066 
1067 	pr_notice("set_par mode %dx%d\n", info->var.xres, info->var.yres);
1068 
1069 	result = dlfb_set_video_mode(dev, &info->var);
1070 
1071 	if ((result == 0) && (dev->fb_count == 0)) {
1072 
1073 		/* paint greenscreen */
1074 
1075 		pix_framebuffer = (u16 *) info->screen_base;
1076 		for (i = 0; i < info->fix.smem_len / 2; i++)
1077 			pix_framebuffer[i] = 0x37e6;
1078 
1079 		dlfb_handle_damage(dev, 0, 0, info->var.xres, info->var.yres,
1080 				   info->screen_base);
1081 	}
1082 
1083 	return result;
1084 }
1085 
1086 /* To fonzi the jukebox (e.g. make blanking changes take effect) */
1087 static char *dlfb_dummy_render(char *buf)
1088 {
1089 	*buf++ = 0xAF;
1090 	*buf++ = 0x6A; /* copy */
1091 	*buf++ = 0x00; /* from address*/
1092 	*buf++ = 0x00;
1093 	*buf++ = 0x00;
1094 	*buf++ = 0x01; /* one pixel */
1095 	*buf++ = 0x00; /* to address */
1096 	*buf++ = 0x00;
1097 	*buf++ = 0x00;
1098 	return buf;
1099 }
1100 
1101 /*
1102  * In order to come back from full DPMS off, we need to set the mode again
1103  */
1104 static int dlfb_ops_blank(int blank_mode, struct fb_info *info)
1105 {
1106 	struct dlfb_data *dev = info->par;
1107 	char *bufptr;
1108 	struct urb *urb;
1109 
1110 	pr_info("/dev/fb%d FB_BLANK mode %d --> %d\n",
1111 		info->node, dev->blank_mode, blank_mode);
1112 
1113 	if ((dev->blank_mode == FB_BLANK_POWERDOWN) &&
1114 	    (blank_mode != FB_BLANK_POWERDOWN)) {
1115 
1116 		/* returning from powerdown requires a fresh modeset */
1117 		dlfb_set_video_mode(dev, &info->var);
1118 	}
1119 
1120 	urb = dlfb_get_urb(dev);
1121 	if (!urb)
1122 		return 0;
1123 
1124 	bufptr = (char *) urb->transfer_buffer;
1125 	bufptr = dlfb_vidreg_lock(bufptr);
1126 	bufptr = dlfb_blanking(bufptr, blank_mode);
1127 	bufptr = dlfb_vidreg_unlock(bufptr);
1128 
1129 	/* seems like a render op is needed to have blank change take effect */
1130 	bufptr = dlfb_dummy_render(bufptr);
1131 
1132 	dlfb_submit_urb(dev, urb, bufptr -
1133 			(char *) urb->transfer_buffer);
1134 
1135 	dev->blank_mode = blank_mode;
1136 
1137 	return 0;
1138 }
1139 
1140 static struct fb_ops dlfb_ops = {
1141 	.owner = THIS_MODULE,
1142 	.fb_read = fb_sys_read,
1143 	.fb_write = dlfb_ops_write,
1144 	.fb_setcolreg = dlfb_ops_setcolreg,
1145 	.fb_fillrect = dlfb_ops_fillrect,
1146 	.fb_copyarea = dlfb_ops_copyarea,
1147 	.fb_imageblit = dlfb_ops_imageblit,
1148 	.fb_mmap = dlfb_ops_mmap,
1149 	.fb_ioctl = dlfb_ops_ioctl,
1150 	.fb_open = dlfb_ops_open,
1151 	.fb_release = dlfb_ops_release,
1152 	.fb_blank = dlfb_ops_blank,
1153 	.fb_check_var = dlfb_ops_check_var,
1154 	.fb_set_par = dlfb_ops_set_par,
1155 };
1156 
1157 
1158 /*
1159  * Assumes &info->lock held by caller
1160  * Assumes no active clients have framebuffer open
1161  */
1162 static int dlfb_realloc_framebuffer(struct dlfb_data *dev, struct fb_info *info)
1163 {
1164 	int retval = -ENOMEM;
1165 	int old_len = info->fix.smem_len;
1166 	int new_len;
1167 	unsigned char *old_fb = info->screen_base;
1168 	unsigned char *new_fb;
1169 	unsigned char *new_back = NULL;
1170 
1171 	pr_warn("Reallocating framebuffer. Addresses will change!\n");
1172 
1173 	new_len = info->fix.line_length * info->var.yres;
1174 
1175 	if (PAGE_ALIGN(new_len) > old_len) {
1176 		/*
1177 		 * Alloc system memory for virtual framebuffer
1178 		 */
1179 		new_fb = vmalloc(new_len);
1180 		if (!new_fb) {
1181 			pr_err("Virtual framebuffer alloc failed\n");
1182 			goto error;
1183 		}
1184 
1185 		if (info->screen_base) {
1186 			memcpy(new_fb, old_fb, old_len);
1187 			vfree(info->screen_base);
1188 		}
1189 
1190 		info->screen_base = new_fb;
1191 		info->fix.smem_len = PAGE_ALIGN(new_len);
1192 		info->fix.smem_start = (unsigned long) new_fb;
1193 		info->flags = udlfb_info_flags;
1194 
1195 		/*
1196 		 * Second framebuffer copy to mirror the framebuffer state
1197 		 * on the physical USB device. We can function without this.
1198 		 * But with imperfect damage info we may send pixels over USB
1199 		 * that were, in fact, unchanged - wasting limited USB bandwidth
1200 		 */
1201 		if (shadow)
1202 			new_back = vzalloc(new_len);
1203 		if (!new_back)
1204 			pr_info("No shadow/backing buffer allocated\n");
1205 		else {
1206 			if (dev->backing_buffer)
1207 				vfree(dev->backing_buffer);
1208 			dev->backing_buffer = new_back;
1209 		}
1210 	}
1211 
1212 	retval = 0;
1213 
1214 error:
1215 	return retval;
1216 }
1217 
1218 /*
1219  * 1) Get EDID from hw, or use sw default
1220  * 2) Parse into various fb_info structs
1221  * 3) Allocate virtual framebuffer memory to back highest res mode
1222  *
1223  * Parses EDID into three places used by various parts of fbdev:
1224  * fb_var_screeninfo contains the timing of the monitor's preferred mode
1225  * fb_info.monspecs is full parsed EDID info, including monspecs.modedb
1226  * fb_info.modelist is a linked list of all monitor & VESA modes which work
1227  *
1228  * If EDID is not readable/valid, then modelist is all VESA modes,
1229  * monspecs is NULL, and fb_var_screeninfo is set to safe VESA mode
1230  * Returns 0 if successful
1231  */
1232 static int dlfb_setup_modes(struct dlfb_data *dev,
1233 			   struct fb_info *info,
1234 			   char *default_edid, size_t default_edid_size)
1235 {
1236 	int i;
1237 	const struct fb_videomode *default_vmode = NULL;
1238 	int result = 0;
1239 	char *edid;
1240 	int tries = 3;
1241 
1242 	if (info->dev) /* only use mutex if info has been registered */
1243 		mutex_lock(&info->lock);
1244 
1245 	edid = kmalloc(EDID_LENGTH, GFP_KERNEL);
1246 	if (!edid) {
1247 		result = -ENOMEM;
1248 		goto error;
1249 	}
1250 
1251 	fb_destroy_modelist(&info->modelist);
1252 	memset(&info->monspecs, 0, sizeof(info->monspecs));
1253 
1254 	/*
1255 	 * Try to (re)read EDID from hardware first
1256 	 * EDID data may return, but not parse as valid
1257 	 * Try again a few times, in case of e.g. analog cable noise
1258 	 */
1259 	while (tries--) {
1260 
1261 		i = dlfb_get_edid(dev, edid, EDID_LENGTH);
1262 
1263 		if (i >= EDID_LENGTH)
1264 			fb_edid_to_monspecs(edid, &info->monspecs);
1265 
1266 		if (info->monspecs.modedb_len > 0) {
1267 			dev->edid = edid;
1268 			dev->edid_size = i;
1269 			break;
1270 		}
1271 	}
1272 
1273 	/* If that fails, use a previously returned EDID if available */
1274 	if (info->monspecs.modedb_len == 0) {
1275 
1276 		pr_err("Unable to get valid EDID from device/display\n");
1277 
1278 		if (dev->edid) {
1279 			fb_edid_to_monspecs(dev->edid, &info->monspecs);
1280 			if (info->monspecs.modedb_len > 0)
1281 				pr_err("Using previously queried EDID\n");
1282 		}
1283 	}
1284 
1285 	/* If that fails, use the default EDID we were handed */
1286 	if (info->monspecs.modedb_len == 0) {
1287 		if (default_edid_size >= EDID_LENGTH) {
1288 			fb_edid_to_monspecs(default_edid, &info->monspecs);
1289 			if (info->monspecs.modedb_len > 0) {
1290 				memcpy(edid, default_edid, default_edid_size);
1291 				dev->edid = edid;
1292 				dev->edid_size = default_edid_size;
1293 				pr_err("Using default/backup EDID\n");
1294 			}
1295 		}
1296 	}
1297 
1298 	/* If we've got modes, let's pick a best default mode */
1299 	if (info->monspecs.modedb_len > 0) {
1300 
1301 		for (i = 0; i < info->monspecs.modedb_len; i++) {
1302 			if (dlfb_is_valid_mode(&info->monspecs.modedb[i], info))
1303 				fb_add_videomode(&info->monspecs.modedb[i],
1304 					&info->modelist);
1305 			else {
1306 				if (i == 0)
1307 					/* if we've removed top/best mode */
1308 					info->monspecs.misc
1309 						&= ~FB_MISC_1ST_DETAIL;
1310 			}
1311 		}
1312 
1313 		default_vmode = fb_find_best_display(&info->monspecs,
1314 						     &info->modelist);
1315 	}
1316 
1317 	/* If everything else has failed, fall back to safe default mode */
1318 	if (default_vmode == NULL) {
1319 
1320 		struct fb_videomode fb_vmode = {0};
1321 
1322 		/*
1323 		 * Add the standard VESA modes to our modelist
1324 		 * Since we don't have EDID, there may be modes that
1325 		 * overspec monitor and/or are incorrect aspect ratio, etc.
1326 		 * But at least the user has a chance to choose
1327 		 */
1328 		for (i = 0; i < VESA_MODEDB_SIZE; i++) {
1329 			if (dlfb_is_valid_mode((struct fb_videomode *)
1330 						&vesa_modes[i], info))
1331 				fb_add_videomode(&vesa_modes[i],
1332 						 &info->modelist);
1333 		}
1334 
1335 		/*
1336 		 * default to resolution safe for projectors
1337 		 * (since they are most common case without EDID)
1338 		 */
1339 		fb_vmode.xres = 800;
1340 		fb_vmode.yres = 600;
1341 		fb_vmode.refresh = 60;
1342 		default_vmode = fb_find_nearest_mode(&fb_vmode,
1343 						     &info->modelist);
1344 	}
1345 
1346 	/* If we have good mode and no active clients*/
1347 	if ((default_vmode != NULL) && (dev->fb_count == 0)) {
1348 
1349 		fb_videomode_to_var(&info->var, default_vmode);
1350 		dlfb_var_color_format(&info->var);
1351 
1352 		/*
1353 		 * with mode size info, we can now alloc our framebuffer.
1354 		 */
1355 		memcpy(&info->fix, &dlfb_fix, sizeof(dlfb_fix));
1356 		info->fix.line_length = info->var.xres *
1357 			(info->var.bits_per_pixel / 8);
1358 
1359 		result = dlfb_realloc_framebuffer(dev, info);
1360 
1361 	} else
1362 		result = -EINVAL;
1363 
1364 error:
1365 	if (edid && (dev->edid != edid))
1366 		kfree(edid);
1367 
1368 	if (info->dev)
1369 		mutex_unlock(&info->lock);
1370 
1371 	return result;
1372 }
1373 
1374 static ssize_t metrics_bytes_rendered_show(struct device *fbdev,
1375 				   struct device_attribute *a, char *buf) {
1376 	struct fb_info *fb_info = dev_get_drvdata(fbdev);
1377 	struct dlfb_data *dev = fb_info->par;
1378 	return snprintf(buf, PAGE_SIZE, "%u\n",
1379 			atomic_read(&dev->bytes_rendered));
1380 }
1381 
1382 static ssize_t metrics_bytes_identical_show(struct device *fbdev,
1383 				   struct device_attribute *a, char *buf) {
1384 	struct fb_info *fb_info = dev_get_drvdata(fbdev);
1385 	struct dlfb_data *dev = fb_info->par;
1386 	return snprintf(buf, PAGE_SIZE, "%u\n",
1387 			atomic_read(&dev->bytes_identical));
1388 }
1389 
1390 static ssize_t metrics_bytes_sent_show(struct device *fbdev,
1391 				   struct device_attribute *a, char *buf) {
1392 	struct fb_info *fb_info = dev_get_drvdata(fbdev);
1393 	struct dlfb_data *dev = fb_info->par;
1394 	return snprintf(buf, PAGE_SIZE, "%u\n",
1395 			atomic_read(&dev->bytes_sent));
1396 }
1397 
1398 static ssize_t metrics_cpu_kcycles_used_show(struct device *fbdev,
1399 				   struct device_attribute *a, char *buf) {
1400 	struct fb_info *fb_info = dev_get_drvdata(fbdev);
1401 	struct dlfb_data *dev = fb_info->par;
1402 	return snprintf(buf, PAGE_SIZE, "%u\n",
1403 			atomic_read(&dev->cpu_kcycles_used));
1404 }
1405 
1406 static ssize_t edid_show(
1407 			struct file *filp,
1408 			struct kobject *kobj, struct bin_attribute *a,
1409 			 char *buf, loff_t off, size_t count) {
1410 	struct device *fbdev = container_of(kobj, struct device, kobj);
1411 	struct fb_info *fb_info = dev_get_drvdata(fbdev);
1412 	struct dlfb_data *dev = fb_info->par;
1413 
1414 	if (dev->edid == NULL)
1415 		return 0;
1416 
1417 	if ((off >= dev->edid_size) || (count > dev->edid_size))
1418 		return 0;
1419 
1420 	if (off + count > dev->edid_size)
1421 		count = dev->edid_size - off;
1422 
1423 	pr_info("sysfs edid copy %p to %p, %d bytes\n",
1424 		dev->edid, buf, (int) count);
1425 
1426 	memcpy(buf, dev->edid, count);
1427 
1428 	return count;
1429 }
1430 
1431 static ssize_t edid_store(
1432 			struct file *filp,
1433 			struct kobject *kobj, struct bin_attribute *a,
1434 			char *src, loff_t src_off, size_t src_size) {
1435 	struct device *fbdev = container_of(kobj, struct device, kobj);
1436 	struct fb_info *fb_info = dev_get_drvdata(fbdev);
1437 	struct dlfb_data *dev = fb_info->par;
1438 	int ret;
1439 
1440 	/* We only support write of entire EDID at once, no offset*/
1441 	if ((src_size != EDID_LENGTH) || (src_off != 0))
1442 		return -EINVAL;
1443 
1444 	ret = dlfb_setup_modes(dev, fb_info, src, src_size);
1445 	if (ret)
1446 		return ret;
1447 
1448 	if (!dev->edid || memcmp(src, dev->edid, src_size))
1449 		return -EINVAL;
1450 
1451 	pr_info("sysfs written EDID is new default\n");
1452 	dlfb_ops_set_par(fb_info);
1453 	return src_size;
1454 }
1455 
1456 static ssize_t metrics_reset_store(struct device *fbdev,
1457 			   struct device_attribute *attr,
1458 			   const char *buf, size_t count)
1459 {
1460 	struct fb_info *fb_info = dev_get_drvdata(fbdev);
1461 	struct dlfb_data *dev = fb_info->par;
1462 
1463 	atomic_set(&dev->bytes_rendered, 0);
1464 	atomic_set(&dev->bytes_identical, 0);
1465 	atomic_set(&dev->bytes_sent, 0);
1466 	atomic_set(&dev->cpu_kcycles_used, 0);
1467 
1468 	return count;
1469 }
1470 
1471 static struct bin_attribute edid_attr = {
1472 	.attr.name = "edid",
1473 	.attr.mode = 0666,
1474 	.size = EDID_LENGTH,
1475 	.read = edid_show,
1476 	.write = edid_store
1477 };
1478 
1479 static struct device_attribute fb_device_attrs[] = {
1480 	__ATTR_RO(metrics_bytes_rendered),
1481 	__ATTR_RO(metrics_bytes_identical),
1482 	__ATTR_RO(metrics_bytes_sent),
1483 	__ATTR_RO(metrics_cpu_kcycles_used),
1484 	__ATTR(metrics_reset, S_IWUSR, NULL, metrics_reset_store),
1485 };
1486 
1487 /*
1488  * This is necessary before we can communicate with the display controller.
1489  */
1490 static int dlfb_select_std_channel(struct dlfb_data *dev)
1491 {
1492 	int ret;
1493 	u8 set_def_chn[] = {	   0x57, 0xCD, 0xDC, 0xA7,
1494 				0x1C, 0x88, 0x5E, 0x15,
1495 				0x60, 0xFE, 0xC6, 0x97,
1496 				0x16, 0x3D, 0x47, 0xF2  };
1497 
1498 	ret = usb_control_msg(dev->udev, usb_sndctrlpipe(dev->udev, 0),
1499 			NR_USB_REQUEST_CHANNEL,
1500 			(USB_DIR_OUT | USB_TYPE_VENDOR), 0, 0,
1501 			set_def_chn, sizeof(set_def_chn), USB_CTRL_SET_TIMEOUT);
1502 	return ret;
1503 }
1504 
1505 static int dlfb_parse_vendor_descriptor(struct dlfb_data *dev,
1506 					struct usb_interface *interface)
1507 {
1508 	char *desc;
1509 	char *buf;
1510 	char *desc_end;
1511 
1512 	int total_len = 0;
1513 
1514 	buf = kzalloc(MAX_VENDOR_DESCRIPTOR_SIZE, GFP_KERNEL);
1515 	if (!buf)
1516 		return false;
1517 	desc = buf;
1518 
1519 	total_len = usb_get_descriptor(interface_to_usbdev(interface),
1520 					0x5f, /* vendor specific */
1521 					0, desc, MAX_VENDOR_DESCRIPTOR_SIZE);
1522 
1523 	/* if not found, look in configuration descriptor */
1524 	if (total_len < 0) {
1525 		if (0 == usb_get_extra_descriptor(interface->cur_altsetting,
1526 			0x5f, &desc))
1527 			total_len = (int) desc[0];
1528 	}
1529 
1530 	if (total_len > 5) {
1531 		pr_info("vendor descriptor length:%x data:%02x %02x %02x %02x" \
1532 			"%02x %02x %02x %02x %02x %02x %02x\n",
1533 			total_len, desc[0],
1534 			desc[1], desc[2], desc[3], desc[4], desc[5], desc[6],
1535 			desc[7], desc[8], desc[9], desc[10]);
1536 
1537 		if ((desc[0] != total_len) || /* descriptor length */
1538 		    (desc[1] != 0x5f) ||   /* vendor descriptor type */
1539 		    (desc[2] != 0x01) ||   /* version (2 bytes) */
1540 		    (desc[3] != 0x00) ||
1541 		    (desc[4] != total_len - 2)) /* length after type */
1542 			goto unrecognized;
1543 
1544 		desc_end = desc + total_len;
1545 		desc += 5; /* the fixed header we've already parsed */
1546 
1547 		while (desc < desc_end) {
1548 			u8 length;
1549 			u16 key;
1550 
1551 			key = le16_to_cpu(*((u16 *) desc));
1552 			desc += sizeof(u16);
1553 			length = *desc;
1554 			desc++;
1555 
1556 			switch (key) {
1557 			case 0x0200: { /* max_area */
1558 				u32 max_area;
1559 				max_area = le32_to_cpu(*((u32 *)desc));
1560 				pr_warn("DL chip limited to %d pixel modes\n",
1561 					max_area);
1562 				dev->sku_pixel_limit = max_area;
1563 				break;
1564 			}
1565 			default:
1566 				break;
1567 			}
1568 			desc += length;
1569 		}
1570 	} else {
1571 		pr_info("vendor descriptor not available (%d)\n", total_len);
1572 	}
1573 
1574 	goto success;
1575 
1576 unrecognized:
1577 	/* allow udlfb to load for now even if firmware unrecognized */
1578 	pr_err("Unrecognized vendor firmware descriptor\n");
1579 
1580 success:
1581 	kfree(buf);
1582 	return true;
1583 }
1584 
1585 static void dlfb_init_framebuffer_work(struct work_struct *work);
1586 
1587 static int dlfb_usb_probe(struct usb_interface *interface,
1588 			const struct usb_device_id *id)
1589 {
1590 	struct usb_device *usbdev;
1591 	struct dlfb_data *dev = NULL;
1592 	int retval = -ENOMEM;
1593 
1594 	/* usb initialization */
1595 
1596 	usbdev = interface_to_usbdev(interface);
1597 
1598 	dev = kzalloc(sizeof(*dev), GFP_KERNEL);
1599 	if (dev == NULL) {
1600 		dev_err(&interface->dev, "dlfb_usb_probe: failed alloc of dev struct\n");
1601 		goto error;
1602 	}
1603 
1604 	kref_init(&dev->kref); /* matching kref_put in usb .disconnect fn */
1605 
1606 	dev->udev = usbdev;
1607 	dev->gdev = &usbdev->dev; /* our generic struct device * */
1608 	usb_set_intfdata(interface, dev);
1609 
1610 	pr_info("%s %s - serial #%s\n",
1611 		usbdev->manufacturer, usbdev->product, usbdev->serial);
1612 	pr_info("vid_%04x&pid_%04x&rev_%04x driver's dlfb_data struct at %p\n",
1613 		usbdev->descriptor.idVendor, usbdev->descriptor.idProduct,
1614 		usbdev->descriptor.bcdDevice, dev);
1615 	pr_info("console enable=%d\n", console);
1616 	pr_info("fb_defio enable=%d\n", fb_defio);
1617 	pr_info("shadow enable=%d\n", shadow);
1618 
1619 	dev->sku_pixel_limit = 2048 * 1152; /* default to maximum */
1620 
1621 	if (!dlfb_parse_vendor_descriptor(dev, interface)) {
1622 		pr_err("firmware not recognized. Assume incompatible device\n");
1623 		goto error;
1624 	}
1625 
1626 	if (pixel_limit) {
1627 		pr_warn("DL chip limit of %d overridden"
1628 			" by module param to %d\n",
1629 			dev->sku_pixel_limit, pixel_limit);
1630 		dev->sku_pixel_limit = pixel_limit;
1631 	}
1632 
1633 
1634 	if (!dlfb_alloc_urb_list(dev, WRITES_IN_FLIGHT, MAX_TRANSFER)) {
1635 		retval = -ENOMEM;
1636 		pr_err("dlfb_alloc_urb_list failed\n");
1637 		goto error;
1638 	}
1639 
1640 	kref_get(&dev->kref); /* matching kref_put in free_framebuffer_work */
1641 
1642 	/* We don't register a new USB class. Our client interface is fbdev */
1643 
1644 	/* Workitem keep things fast & simple during USB enumeration */
1645 	INIT_DELAYED_WORK(&dev->init_framebuffer_work,
1646 			  dlfb_init_framebuffer_work);
1647 	schedule_delayed_work(&dev->init_framebuffer_work, 0);
1648 
1649 	return 0;
1650 
1651 error:
1652 	if (dev) {
1653 
1654 		kref_put(&dev->kref, dlfb_free); /* ref for framebuffer */
1655 		kref_put(&dev->kref, dlfb_free); /* last ref from kref_init */
1656 
1657 		/* dev has been deallocated. Do not dereference */
1658 	}
1659 
1660 	return retval;
1661 }
1662 
1663 static void dlfb_init_framebuffer_work(struct work_struct *work)
1664 {
1665 	struct dlfb_data *dev = container_of(work, struct dlfb_data,
1666 					     init_framebuffer_work.work);
1667 	struct fb_info *info;
1668 	int retval;
1669 	int i;
1670 
1671 	/* allocates framebuffer driver structure, not framebuffer memory */
1672 	info = framebuffer_alloc(0, dev->gdev);
1673 	if (!info) {
1674 		retval = -ENOMEM;
1675 		pr_err("framebuffer_alloc failed\n");
1676 		goto error;
1677 	}
1678 
1679 	dev->info = info;
1680 	info->par = dev;
1681 	info->pseudo_palette = dev->pseudo_palette;
1682 	info->fbops = &dlfb_ops;
1683 
1684 	retval = fb_alloc_cmap(&info->cmap, 256, 0);
1685 	if (retval < 0) {
1686 		pr_err("fb_alloc_cmap failed %x\n", retval);
1687 		goto error;
1688 	}
1689 
1690 	INIT_DELAYED_WORK(&dev->free_framebuffer_work,
1691 			  dlfb_free_framebuffer_work);
1692 
1693 	INIT_LIST_HEAD(&info->modelist);
1694 
1695 	retval = dlfb_setup_modes(dev, info, NULL, 0);
1696 	if (retval != 0) {
1697 		pr_err("unable to find common mode for display and adapter\n");
1698 		goto error;
1699 	}
1700 
1701 	/* ready to begin using device */
1702 
1703 	atomic_set(&dev->usb_active, 1);
1704 	dlfb_select_std_channel(dev);
1705 
1706 	dlfb_ops_check_var(&info->var, info);
1707 	dlfb_ops_set_par(info);
1708 
1709 	retval = register_framebuffer(info);
1710 	if (retval < 0) {
1711 		pr_err("register_framebuffer failed %d\n", retval);
1712 		goto error;
1713 	}
1714 
1715 	for (i = 0; i < ARRAY_SIZE(fb_device_attrs); i++) {
1716 		retval = device_create_file(info->dev, &fb_device_attrs[i]);
1717 		if (retval) {
1718 			pr_warn("device_create_file failed %d\n", retval);
1719 		}
1720 	}
1721 
1722 	retval = device_create_bin_file(info->dev, &edid_attr);
1723 	if (retval) {
1724 		pr_warn("device_create_bin_file failed %d\n", retval);
1725 	}
1726 
1727 	pr_info("DisplayLink USB device /dev/fb%d attached. %dx%d resolution."
1728 			" Using %dK framebuffer memory\n", info->node,
1729 			info->var.xres, info->var.yres,
1730 			((dev->backing_buffer) ?
1731 			info->fix.smem_len * 2 : info->fix.smem_len) >> 10);
1732 	return;
1733 
1734 error:
1735 	dlfb_free_framebuffer(dev);
1736 }
1737 
1738 static void dlfb_usb_disconnect(struct usb_interface *interface)
1739 {
1740 	struct dlfb_data *dev;
1741 	struct fb_info *info;
1742 	int i;
1743 
1744 	dev = usb_get_intfdata(interface);
1745 	info = dev->info;
1746 
1747 	pr_info("USB disconnect starting\n");
1748 
1749 	/* we virtualize until all fb clients release. Then we free */
1750 	dev->virtualized = true;
1751 
1752 	/* When non-active we'll update virtual framebuffer, but no new urbs */
1753 	atomic_set(&dev->usb_active, 0);
1754 
1755 	/* this function will wait for all in-flight urbs to complete */
1756 	dlfb_free_urb_list(dev);
1757 
1758 	if (info) {
1759 		/* remove udlfb's sysfs interfaces */
1760 		for (i = 0; i < ARRAY_SIZE(fb_device_attrs); i++)
1761 			device_remove_file(info->dev, &fb_device_attrs[i]);
1762 		device_remove_bin_file(info->dev, &edid_attr);
1763 		unlink_framebuffer(info);
1764 	}
1765 
1766 	usb_set_intfdata(interface, NULL);
1767 	dev->udev = NULL;
1768 	dev->gdev = NULL;
1769 
1770 	/* if clients still have us open, will be freed on last close */
1771 	if (dev->fb_count == 0)
1772 		schedule_delayed_work(&dev->free_framebuffer_work, 0);
1773 
1774 	/* release reference taken by kref_init in probe() */
1775 	kref_put(&dev->kref, dlfb_free);
1776 
1777 	/* consider dlfb_data freed */
1778 
1779 	return;
1780 }
1781 
1782 static struct usb_driver dlfb_driver = {
1783 	.name = "udlfb",
1784 	.probe = dlfb_usb_probe,
1785 	.disconnect = dlfb_usb_disconnect,
1786 	.id_table = id_table,
1787 };
1788 
1789 module_usb_driver(dlfb_driver);
1790 
1791 static void dlfb_urb_completion(struct urb *urb)
1792 {
1793 	struct urb_node *unode = urb->context;
1794 	struct dlfb_data *dev = unode->dev;
1795 	unsigned long flags;
1796 
1797 	/* sync/async unlink faults aren't errors */
1798 	if (urb->status) {
1799 		if (!(urb->status == -ENOENT ||
1800 		    urb->status == -ECONNRESET ||
1801 		    urb->status == -ESHUTDOWN)) {
1802 			pr_err("%s - nonzero write bulk status received: %d\n",
1803 				__func__, urb->status);
1804 			atomic_set(&dev->lost_pixels, 1);
1805 		}
1806 	}
1807 
1808 	urb->transfer_buffer_length = dev->urbs.size; /* reset to actual */
1809 
1810 	spin_lock_irqsave(&dev->urbs.lock, flags);
1811 	list_add_tail(&unode->entry, &dev->urbs.list);
1812 	dev->urbs.available++;
1813 	spin_unlock_irqrestore(&dev->urbs.lock, flags);
1814 
1815 	/*
1816 	 * When using fb_defio, we deadlock if up() is called
1817 	 * while another is waiting. So queue to another process.
1818 	 */
1819 	if (fb_defio)
1820 		schedule_delayed_work(&unode->release_urb_work, 0);
1821 	else
1822 		up(&dev->urbs.limit_sem);
1823 }
1824 
1825 static void dlfb_free_urb_list(struct dlfb_data *dev)
1826 {
1827 	int count = dev->urbs.count;
1828 	struct list_head *node;
1829 	struct urb_node *unode;
1830 	struct urb *urb;
1831 	int ret;
1832 	unsigned long flags;
1833 
1834 	pr_notice("Freeing all render urbs\n");
1835 
1836 	/* keep waiting and freeing, until we've got 'em all */
1837 	while (count--) {
1838 
1839 		/* Getting interrupted means a leak, but ok at disconnect */
1840 		ret = down_interruptible(&dev->urbs.limit_sem);
1841 		if (ret)
1842 			break;
1843 
1844 		spin_lock_irqsave(&dev->urbs.lock, flags);
1845 
1846 		node = dev->urbs.list.next; /* have reserved one with sem */
1847 		list_del_init(node);
1848 
1849 		spin_unlock_irqrestore(&dev->urbs.lock, flags);
1850 
1851 		unode = list_entry(node, struct urb_node, entry);
1852 		urb = unode->urb;
1853 
1854 		/* Free each separately allocated piece */
1855 		usb_free_coherent(urb->dev, dev->urbs.size,
1856 				  urb->transfer_buffer, urb->transfer_dma);
1857 		usb_free_urb(urb);
1858 		kfree(node);
1859 	}
1860 
1861 	dev->urbs.count = 0;
1862 }
1863 
1864 static int dlfb_alloc_urb_list(struct dlfb_data *dev, int count, size_t size)
1865 {
1866 	int i = 0;
1867 	struct urb *urb;
1868 	struct urb_node *unode;
1869 	char *buf;
1870 
1871 	spin_lock_init(&dev->urbs.lock);
1872 
1873 	dev->urbs.size = size;
1874 	INIT_LIST_HEAD(&dev->urbs.list);
1875 
1876 	while (i < count) {
1877 		unode = kzalloc(sizeof(struct urb_node), GFP_KERNEL);
1878 		if (!unode)
1879 			break;
1880 		unode->dev = dev;
1881 
1882 		INIT_DELAYED_WORK(&unode->release_urb_work,
1883 			  dlfb_release_urb_work);
1884 
1885 		urb = usb_alloc_urb(0, GFP_KERNEL);
1886 		if (!urb) {
1887 			kfree(unode);
1888 			break;
1889 		}
1890 		unode->urb = urb;
1891 
1892 		buf = usb_alloc_coherent(dev->udev, MAX_TRANSFER, GFP_KERNEL,
1893 					 &urb->transfer_dma);
1894 		if (!buf) {
1895 			kfree(unode);
1896 			usb_free_urb(urb);
1897 			break;
1898 		}
1899 
1900 		/* urb->transfer_buffer_length set to actual before submit */
1901 		usb_fill_bulk_urb(urb, dev->udev, usb_sndbulkpipe(dev->udev, 1),
1902 			buf, size, dlfb_urb_completion, unode);
1903 		urb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;
1904 
1905 		list_add_tail(&unode->entry, &dev->urbs.list);
1906 
1907 		i++;
1908 	}
1909 
1910 	sema_init(&dev->urbs.limit_sem, i);
1911 	dev->urbs.count = i;
1912 	dev->urbs.available = i;
1913 
1914 	pr_notice("allocated %d %d byte urbs\n", i, (int) size);
1915 
1916 	return i;
1917 }
1918 
1919 static struct urb *dlfb_get_urb(struct dlfb_data *dev)
1920 {
1921 	int ret = 0;
1922 	struct list_head *entry;
1923 	struct urb_node *unode;
1924 	struct urb *urb = NULL;
1925 	unsigned long flags;
1926 
1927 	/* Wait for an in-flight buffer to complete and get re-queued */
1928 	ret = down_timeout(&dev->urbs.limit_sem, GET_URB_TIMEOUT);
1929 	if (ret) {
1930 		atomic_set(&dev->lost_pixels, 1);
1931 		pr_warn("wait for urb interrupted: %x available: %d\n",
1932 		       ret, dev->urbs.available);
1933 		goto error;
1934 	}
1935 
1936 	spin_lock_irqsave(&dev->urbs.lock, flags);
1937 
1938 	BUG_ON(list_empty(&dev->urbs.list)); /* reserved one with limit_sem */
1939 	entry = dev->urbs.list.next;
1940 	list_del_init(entry);
1941 	dev->urbs.available--;
1942 
1943 	spin_unlock_irqrestore(&dev->urbs.lock, flags);
1944 
1945 	unode = list_entry(entry, struct urb_node, entry);
1946 	urb = unode->urb;
1947 
1948 error:
1949 	return urb;
1950 }
1951 
1952 static int dlfb_submit_urb(struct dlfb_data *dev, struct urb *urb, size_t len)
1953 {
1954 	int ret;
1955 
1956 	BUG_ON(len > dev->urbs.size);
1957 
1958 	urb->transfer_buffer_length = len; /* set to actual payload len */
1959 	ret = usb_submit_urb(urb, GFP_KERNEL);
1960 	if (ret) {
1961 		dlfb_urb_completion(urb); /* because no one else will */
1962 		atomic_set(&dev->lost_pixels, 1);
1963 		pr_err("usb_submit_urb error %x\n", ret);
1964 	}
1965 	return ret;
1966 }
1967 
1968 module_param(console, bool, S_IWUSR | S_IRUSR | S_IWGRP | S_IRGRP);
1969 MODULE_PARM_DESC(console, "Allow fbcon to open framebuffer");
1970 
1971 module_param(fb_defio, bool, S_IWUSR | S_IRUSR | S_IWGRP | S_IRGRP);
1972 MODULE_PARM_DESC(fb_defio, "Page fault detection of mmap writes");
1973 
1974 module_param(shadow, bool, S_IWUSR | S_IRUSR | S_IWGRP | S_IRGRP);
1975 MODULE_PARM_DESC(shadow, "Shadow vid mem. Disable to save mem but lose perf");
1976 
1977 module_param(pixel_limit, int, S_IWUSR | S_IRUSR | S_IWGRP | S_IRGRP);
1978 MODULE_PARM_DESC(pixel_limit, "Force limit on max mode (in x*y pixels)");
1979 
1980 MODULE_AUTHOR("Roberto De Ioris <roberto@unbit.it>, "
1981 	      "Jaya Kumar <jayakumar.lkml@gmail.com>, "
1982 	      "Bernie Thompson <bernie@plugable.com>");
1983 MODULE_DESCRIPTION("DisplayLink kernel framebuffer driver");
1984 MODULE_LICENSE("GPL");
1985 
1986