xref: /openbmc/linux/drivers/video/fbdev/udlfb.c (revision 7f2e85840871f199057e65232ebde846192ed989)
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 #include <linux/module.h>
20 #include <linux/kernel.h>
21 #include <linux/init.h>
22 #include <linux/usb.h>
23 #include <linux/uaccess.h>
24 #include <linux/mm.h>
25 #include <linux/fb.h>
26 #include <linux/vmalloc.h>
27 #include <linux/slab.h>
28 #include <linux/prefetch.h>
29 #include <linux/delay.h>
30 #include <video/udlfb.h>
31 #include "edid.h"
32 
33 static const struct fb_fix_screeninfo dlfb_fix = {
34 	.id =           "udlfb",
35 	.type =         FB_TYPE_PACKED_PIXELS,
36 	.visual =       FB_VISUAL_TRUECOLOR,
37 	.xpanstep =     0,
38 	.ypanstep =     0,
39 	.ywrapstep =    0,
40 	.accel =        FB_ACCEL_NONE,
41 };
42 
43 static const u32 udlfb_info_flags = FBINFO_DEFAULT | FBINFO_READS_FAST |
44 		FBINFO_VIRTFB |
45 		FBINFO_HWACCEL_IMAGEBLIT | FBINFO_HWACCEL_FILLRECT |
46 		FBINFO_HWACCEL_COPYAREA | FBINFO_MISC_ALWAYS_SETPAR;
47 
48 /*
49  * There are many DisplayLink-based graphics products, all with unique PIDs.
50  * So we match on DisplayLink's VID + Vendor-Defined Interface Class (0xff)
51  * We also require a match on SubClass (0x00) and Protocol (0x00),
52  * which is compatible with all known USB 2.0 era graphics chips and firmware,
53  * but allows DisplayLink to increment those for any future incompatible chips
54  */
55 static const struct usb_device_id id_table[] = {
56 	{.idVendor = 0x17e9,
57 	 .bInterfaceClass = 0xff,
58 	 .bInterfaceSubClass = 0x00,
59 	 .bInterfaceProtocol = 0x00,
60 	 .match_flags = USB_DEVICE_ID_MATCH_VENDOR |
61 		USB_DEVICE_ID_MATCH_INT_CLASS |
62 		USB_DEVICE_ID_MATCH_INT_SUBCLASS |
63 		USB_DEVICE_ID_MATCH_INT_PROTOCOL,
64 	},
65 	{},
66 };
67 MODULE_DEVICE_TABLE(usb, id_table);
68 
69 /* module options */
70 static bool console = 1; /* Allow fbcon to open framebuffer */
71 static bool fb_defio = 1;  /* Detect mmap writes using page faults */
72 static bool shadow = 1; /* Optionally disable shadow framebuffer */
73 static int pixel_limit; /* Optionally force a pixel resolution limit */
74 
75 /* dlfb keeps a list of urbs for efficient bulk transfers */
76 static void dlfb_urb_completion(struct urb *urb);
77 static struct urb *dlfb_get_urb(struct dlfb_data *dlfb);
78 static int dlfb_submit_urb(struct dlfb_data *dlfb, struct urb * urb, size_t len);
79 static int dlfb_alloc_urb_list(struct dlfb_data *dlfb, int count, size_t size);
80 static void dlfb_free_urb_list(struct dlfb_data *dlfb);
81 
82 /*
83  * All DisplayLink bulk operations start with 0xAF, followed by specific code
84  * All operations are written to buffers which then later get sent to device
85  */
86 static char *dlfb_set_register(char *buf, u8 reg, u8 val)
87 {
88 	*buf++ = 0xAF;
89 	*buf++ = 0x20;
90 	*buf++ = reg;
91 	*buf++ = val;
92 	return buf;
93 }
94 
95 static char *dlfb_vidreg_lock(char *buf)
96 {
97 	return dlfb_set_register(buf, 0xFF, 0x00);
98 }
99 
100 static char *dlfb_vidreg_unlock(char *buf)
101 {
102 	return dlfb_set_register(buf, 0xFF, 0xFF);
103 }
104 
105 /*
106  * Map FB_BLANK_* to DisplayLink register
107  * DLReg FB_BLANK_*
108  * ----- -----------------------------
109  *  0x00 FB_BLANK_UNBLANK (0)
110  *  0x01 FB_BLANK (1)
111  *  0x03 FB_BLANK_VSYNC_SUSPEND (2)
112  *  0x05 FB_BLANK_HSYNC_SUSPEND (3)
113  *  0x07 FB_BLANK_POWERDOWN (4) Note: requires modeset to come back
114  */
115 static char *dlfb_blanking(char *buf, int fb_blank)
116 {
117 	u8 reg;
118 
119 	switch (fb_blank) {
120 	case FB_BLANK_POWERDOWN:
121 		reg = 0x07;
122 		break;
123 	case FB_BLANK_HSYNC_SUSPEND:
124 		reg = 0x05;
125 		break;
126 	case FB_BLANK_VSYNC_SUSPEND:
127 		reg = 0x03;
128 		break;
129 	case FB_BLANK_NORMAL:
130 		reg = 0x01;
131 		break;
132 	default:
133 		reg = 0x00;
134 	}
135 
136 	buf = dlfb_set_register(buf, 0x1F, reg);
137 
138 	return buf;
139 }
140 
141 static char *dlfb_set_color_depth(char *buf, u8 selection)
142 {
143 	return dlfb_set_register(buf, 0x00, selection);
144 }
145 
146 static char *dlfb_set_base16bpp(char *wrptr, u32 base)
147 {
148 	/* the base pointer is 16 bits wide, 0x20 is hi byte. */
149 	wrptr = dlfb_set_register(wrptr, 0x20, base >> 16);
150 	wrptr = dlfb_set_register(wrptr, 0x21, base >> 8);
151 	return dlfb_set_register(wrptr, 0x22, base);
152 }
153 
154 /*
155  * DisplayLink HW has separate 16bpp and 8bpp framebuffers.
156  * In 24bpp modes, the low 323 RGB bits go in the 8bpp framebuffer
157  */
158 static char *dlfb_set_base8bpp(char *wrptr, u32 base)
159 {
160 	wrptr = dlfb_set_register(wrptr, 0x26, base >> 16);
161 	wrptr = dlfb_set_register(wrptr, 0x27, base >> 8);
162 	return dlfb_set_register(wrptr, 0x28, base);
163 }
164 
165 static char *dlfb_set_register_16(char *wrptr, u8 reg, u16 value)
166 {
167 	wrptr = dlfb_set_register(wrptr, reg, value >> 8);
168 	return dlfb_set_register(wrptr, reg+1, value);
169 }
170 
171 /*
172  * This is kind of weird because the controller takes some
173  * register values in a different byte order than other registers.
174  */
175 static char *dlfb_set_register_16be(char *wrptr, u8 reg, u16 value)
176 {
177 	wrptr = dlfb_set_register(wrptr, reg, value);
178 	return dlfb_set_register(wrptr, reg+1, value >> 8);
179 }
180 
181 /*
182  * LFSR is linear feedback shift register. The reason we have this is
183  * because the display controller needs to minimize the clock depth of
184  * various counters used in the display path. So this code reverses the
185  * provided value into the lfsr16 value by counting backwards to get
186  * the value that needs to be set in the hardware comparator to get the
187  * same actual count. This makes sense once you read above a couple of
188  * times and think about it from a hardware perspective.
189  */
190 static u16 dlfb_lfsr16(u16 actual_count)
191 {
192 	u32 lv = 0xFFFF; /* This is the lfsr value that the hw starts with */
193 
194 	while (actual_count--) {
195 		lv =	 ((lv << 1) |
196 			(((lv >> 15) ^ (lv >> 4) ^ (lv >> 2) ^ (lv >> 1)) & 1))
197 			& 0xFFFF;
198 	}
199 
200 	return (u16) lv;
201 }
202 
203 /*
204  * This does LFSR conversion on the value that is to be written.
205  * See LFSR explanation above for more detail.
206  */
207 static char *dlfb_set_register_lfsr16(char *wrptr, u8 reg, u16 value)
208 {
209 	return dlfb_set_register_16(wrptr, reg, dlfb_lfsr16(value));
210 }
211 
212 /*
213  * This takes a standard fbdev screeninfo struct and all of its monitor mode
214  * details and converts them into the DisplayLink equivalent register commands.
215  */
216 static char *dlfb_set_vid_cmds(char *wrptr, struct fb_var_screeninfo *var)
217 {
218 	u16 xds, yds;
219 	u16 xde, yde;
220 	u16 yec;
221 
222 	/* x display start */
223 	xds = var->left_margin + var->hsync_len;
224 	wrptr = dlfb_set_register_lfsr16(wrptr, 0x01, xds);
225 	/* x display end */
226 	xde = xds + var->xres;
227 	wrptr = dlfb_set_register_lfsr16(wrptr, 0x03, xde);
228 
229 	/* y display start */
230 	yds = var->upper_margin + var->vsync_len;
231 	wrptr = dlfb_set_register_lfsr16(wrptr, 0x05, yds);
232 	/* y display end */
233 	yde = yds + var->yres;
234 	wrptr = dlfb_set_register_lfsr16(wrptr, 0x07, yde);
235 
236 	/* x end count is active + blanking - 1 */
237 	wrptr = dlfb_set_register_lfsr16(wrptr, 0x09,
238 			xde + var->right_margin - 1);
239 
240 	/* libdlo hardcodes hsync start to 1 */
241 	wrptr = dlfb_set_register_lfsr16(wrptr, 0x0B, 1);
242 
243 	/* hsync end is width of sync pulse + 1 */
244 	wrptr = dlfb_set_register_lfsr16(wrptr, 0x0D, var->hsync_len + 1);
245 
246 	/* hpixels is active pixels */
247 	wrptr = dlfb_set_register_16(wrptr, 0x0F, var->xres);
248 
249 	/* yendcount is vertical active + vertical blanking */
250 	yec = var->yres + var->upper_margin + var->lower_margin +
251 			var->vsync_len;
252 	wrptr = dlfb_set_register_lfsr16(wrptr, 0x11, yec);
253 
254 	/* libdlo hardcodes vsync start to 0 */
255 	wrptr = dlfb_set_register_lfsr16(wrptr, 0x13, 0);
256 
257 	/* vsync end is width of vsync pulse */
258 	wrptr = dlfb_set_register_lfsr16(wrptr, 0x15, var->vsync_len);
259 
260 	/* vpixels is active pixels */
261 	wrptr = dlfb_set_register_16(wrptr, 0x17, var->yres);
262 
263 	/* convert picoseconds to 5kHz multiple for pclk5k = x * 1E12/5k */
264 	wrptr = dlfb_set_register_16be(wrptr, 0x1B,
265 			200*1000*1000/var->pixclock);
266 
267 	return wrptr;
268 }
269 
270 /*
271  * This takes a standard fbdev screeninfo struct that was fetched or prepared
272  * and then generates the appropriate command sequence that then drives the
273  * display controller.
274  */
275 static int dlfb_set_video_mode(struct dlfb_data *dlfb,
276 				struct fb_var_screeninfo *var)
277 {
278 	char *buf;
279 	char *wrptr;
280 	int retval;
281 	int writesize;
282 	struct urb *urb;
283 
284 	if (!atomic_read(&dlfb->usb_active))
285 		return -EPERM;
286 
287 	urb = dlfb_get_urb(dlfb);
288 	if (!urb)
289 		return -ENOMEM;
290 
291 	buf = (char *) urb->transfer_buffer;
292 
293 	/*
294 	* This first section has to do with setting the base address on the
295 	* controller * associated with the display. There are 2 base
296 	* pointers, currently, we only * use the 16 bpp segment.
297 	*/
298 	wrptr = dlfb_vidreg_lock(buf);
299 	wrptr = dlfb_set_color_depth(wrptr, 0x00);
300 	/* set base for 16bpp segment to 0 */
301 	wrptr = dlfb_set_base16bpp(wrptr, 0);
302 	/* set base for 8bpp segment to end of fb */
303 	wrptr = dlfb_set_base8bpp(wrptr, dlfb->info->fix.smem_len);
304 
305 	wrptr = dlfb_set_vid_cmds(wrptr, var);
306 	wrptr = dlfb_blanking(wrptr, FB_BLANK_UNBLANK);
307 	wrptr = dlfb_vidreg_unlock(wrptr);
308 
309 	writesize = wrptr - buf;
310 
311 	retval = dlfb_submit_urb(dlfb, urb, writesize);
312 
313 	dlfb->blank_mode = FB_BLANK_UNBLANK;
314 
315 	return retval;
316 }
317 
318 static int dlfb_ops_mmap(struct fb_info *info, struct vm_area_struct *vma)
319 {
320 	unsigned long start = vma->vm_start;
321 	unsigned long size = vma->vm_end - vma->vm_start;
322 	unsigned long offset = vma->vm_pgoff << PAGE_SHIFT;
323 	unsigned long page, pos;
324 
325 	if (vma->vm_pgoff > (~0UL >> PAGE_SHIFT))
326 		return -EINVAL;
327 	if (size > info->fix.smem_len)
328 		return -EINVAL;
329 	if (offset > info->fix.smem_len - size)
330 		return -EINVAL;
331 
332 	pos = (unsigned long)info->fix.smem_start + offset;
333 
334 	dev_dbg(info->dev, "mmap() framebuffer addr:%lu size:%lu\n",
335 		pos, size);
336 
337 	while (size > 0) {
338 		page = vmalloc_to_pfn((void *)pos);
339 		if (remap_pfn_range(vma, start, page, PAGE_SIZE, PAGE_SHARED))
340 			return -EAGAIN;
341 
342 		start += PAGE_SIZE;
343 		pos += PAGE_SIZE;
344 		if (size > PAGE_SIZE)
345 			size -= PAGE_SIZE;
346 		else
347 			size = 0;
348 	}
349 
350 	return 0;
351 }
352 
353 /*
354  * Trims identical data from front and back of line
355  * Sets new front buffer address and width
356  * And returns byte count of identical pixels
357  * Assumes CPU natural alignment (unsigned long)
358  * for back and front buffer ptrs and width
359  */
360 static int dlfb_trim_hline(const u8 *bback, const u8 **bfront, int *width_bytes)
361 {
362 	int j, k;
363 	const unsigned long *back = (const unsigned long *) bback;
364 	const unsigned long *front = (const unsigned long *) *bfront;
365 	const int width = *width_bytes / sizeof(unsigned long);
366 	int identical = width;
367 	int start = width;
368 	int end = width;
369 
370 	prefetch((void *) front);
371 	prefetch((void *) back);
372 
373 	for (j = 0; j < width; j++) {
374 		if (back[j] != front[j]) {
375 			start = j;
376 			break;
377 		}
378 	}
379 
380 	for (k = width - 1; k > j; k--) {
381 		if (back[k] != front[k]) {
382 			end = k+1;
383 			break;
384 		}
385 	}
386 
387 	identical = start + (width - end);
388 	*bfront = (u8 *) &front[start];
389 	*width_bytes = (end - start) * sizeof(unsigned long);
390 
391 	return identical * sizeof(unsigned long);
392 }
393 
394 /*
395  * Render a command stream for an encoded horizontal line segment of pixels.
396  *
397  * A command buffer holds several commands.
398  * It always begins with a fresh command header
399  * (the protocol doesn't require this, but we enforce it to allow
400  * multiple buffers to be potentially encoded and sent in parallel).
401  * A single command encodes one contiguous horizontal line of pixels
402  *
403  * The function relies on the client to do all allocation, so that
404  * rendering can be done directly to output buffers (e.g. USB URBs).
405  * The function fills the supplied command buffer, providing information
406  * on where it left off, so the client may call in again with additional
407  * buffers if the line will take several buffers to complete.
408  *
409  * A single command can transmit a maximum of 256 pixels,
410  * regardless of the compression ratio (protocol design limit).
411  * To the hardware, 0 for a size byte means 256
412  *
413  * Rather than 256 pixel commands which are either rl or raw encoded,
414  * the rlx command simply assumes alternating raw and rl spans within one cmd.
415  * This has a slightly larger header overhead, but produces more even results.
416  * It also processes all data (read and write) in a single pass.
417  * Performance benchmarks of common cases show it having just slightly better
418  * compression than 256 pixel raw or rle commands, with similar CPU consumpion.
419  * But for very rl friendly data, will compress not quite as well.
420  */
421 static void dlfb_compress_hline(
422 	const uint16_t **pixel_start_ptr,
423 	const uint16_t *const pixel_end,
424 	uint32_t *device_address_ptr,
425 	uint8_t **command_buffer_ptr,
426 	const uint8_t *const cmd_buffer_end)
427 {
428 	const uint16_t *pixel = *pixel_start_ptr;
429 	uint32_t dev_addr  = *device_address_ptr;
430 	uint8_t *cmd = *command_buffer_ptr;
431 	const int bpp = 2;
432 
433 	while ((pixel_end > pixel) &&
434 	       (cmd_buffer_end - MIN_RLX_CMD_BYTES > cmd)) {
435 		uint8_t *raw_pixels_count_byte = NULL;
436 		uint8_t *cmd_pixels_count_byte = NULL;
437 		const uint16_t *raw_pixel_start = NULL;
438 		const uint16_t *cmd_pixel_start, *cmd_pixel_end = NULL;
439 
440 		prefetchw((void *) cmd); /* pull in one cache line at least */
441 
442 		*cmd++ = 0xAF;
443 		*cmd++ = 0x6B;
444 		*cmd++ = (uint8_t) ((dev_addr >> 16) & 0xFF);
445 		*cmd++ = (uint8_t) ((dev_addr >> 8) & 0xFF);
446 		*cmd++ = (uint8_t) ((dev_addr) & 0xFF);
447 
448 		cmd_pixels_count_byte = cmd++; /*  we'll know this later */
449 		cmd_pixel_start = pixel;
450 
451 		raw_pixels_count_byte = cmd++; /*  we'll know this later */
452 		raw_pixel_start = pixel;
453 
454 		cmd_pixel_end = pixel + min(MAX_CMD_PIXELS + 1,
455 			min((int)(pixel_end - pixel),
456 			    (int)(cmd_buffer_end - cmd) / bpp));
457 
458 		prefetch_range((void *) pixel, (cmd_pixel_end - pixel) * bpp);
459 
460 		while (pixel < cmd_pixel_end) {
461 			const uint16_t * const repeating_pixel = pixel;
462 
463 			*(uint16_t *)cmd = cpu_to_be16p(pixel);
464 			cmd += 2;
465 			pixel++;
466 
467 			if (unlikely((pixel < cmd_pixel_end) &&
468 				     (*pixel == *repeating_pixel))) {
469 				/* go back and fill in raw pixel count */
470 				*raw_pixels_count_byte = ((repeating_pixel -
471 						raw_pixel_start) + 1) & 0xFF;
472 
473 				while ((pixel < cmd_pixel_end)
474 				       && (*pixel == *repeating_pixel)) {
475 					pixel++;
476 				}
477 
478 				/* immediately after raw data is repeat byte */
479 				*cmd++ = ((pixel - repeating_pixel) - 1) & 0xFF;
480 
481 				/* Then start another raw pixel span */
482 				raw_pixel_start = pixel;
483 				raw_pixels_count_byte = cmd++;
484 			}
485 		}
486 
487 		if (pixel > raw_pixel_start) {
488 			/* finalize last RAW span */
489 			*raw_pixels_count_byte = (pixel-raw_pixel_start) & 0xFF;
490 		}
491 
492 		*cmd_pixels_count_byte = (pixel - cmd_pixel_start) & 0xFF;
493 		dev_addr += (pixel - cmd_pixel_start) * bpp;
494 	}
495 
496 	if (cmd_buffer_end <= MIN_RLX_CMD_BYTES + cmd) {
497 		/* Fill leftover bytes with no-ops */
498 		if (cmd_buffer_end > cmd)
499 			memset(cmd, 0xAF, cmd_buffer_end - cmd);
500 		cmd = (uint8_t *) cmd_buffer_end;
501 	}
502 
503 	*command_buffer_ptr = cmd;
504 	*pixel_start_ptr = pixel;
505 	*device_address_ptr = dev_addr;
506 }
507 
508 /*
509  * There are 3 copies of every pixel: The front buffer that the fbdev
510  * client renders to, the actual framebuffer across the USB bus in hardware
511  * (that we can only write to, slowly, and can never read), and (optionally)
512  * our shadow copy that tracks what's been sent to that hardware buffer.
513  */
514 static int dlfb_render_hline(struct dlfb_data *dlfb, struct urb **urb_ptr,
515 			      const char *front, char **urb_buf_ptr,
516 			      u32 byte_offset, u32 byte_width,
517 			      int *ident_ptr, int *sent_ptr)
518 {
519 	const u8 *line_start, *line_end, *next_pixel;
520 	u32 dev_addr = dlfb->base16 + byte_offset;
521 	struct urb *urb = *urb_ptr;
522 	u8 *cmd = *urb_buf_ptr;
523 	u8 *cmd_end = (u8 *) urb->transfer_buffer + urb->transfer_buffer_length;
524 
525 	line_start = (u8 *) (front + byte_offset);
526 	next_pixel = line_start;
527 	line_end = next_pixel + byte_width;
528 
529 	if (dlfb->backing_buffer) {
530 		int offset;
531 		const u8 *back_start = (u8 *) (dlfb->backing_buffer
532 						+ byte_offset);
533 
534 		*ident_ptr += dlfb_trim_hline(back_start, &next_pixel,
535 			&byte_width);
536 
537 		offset = next_pixel - line_start;
538 		line_end = next_pixel + byte_width;
539 		dev_addr += offset;
540 		back_start += offset;
541 		line_start += offset;
542 
543 		memcpy((char *)back_start, (char *) line_start,
544 		       byte_width);
545 	}
546 
547 	while (next_pixel < line_end) {
548 
549 		dlfb_compress_hline((const uint16_t **) &next_pixel,
550 			     (const uint16_t *) line_end, &dev_addr,
551 			(u8 **) &cmd, (u8 *) cmd_end);
552 
553 		if (cmd >= cmd_end) {
554 			int len = cmd - (u8 *) urb->transfer_buffer;
555 			if (dlfb_submit_urb(dlfb, urb, len))
556 				return 1; /* lost pixels is set */
557 			*sent_ptr += len;
558 			urb = dlfb_get_urb(dlfb);
559 			if (!urb)
560 				return 1; /* lost_pixels is set */
561 			*urb_ptr = urb;
562 			cmd = urb->transfer_buffer;
563 			cmd_end = &cmd[urb->transfer_buffer_length];
564 		}
565 	}
566 
567 	*urb_buf_ptr = cmd;
568 
569 	return 0;
570 }
571 
572 static int dlfb_handle_damage(struct dlfb_data *dlfb, int x, int y,
573 	       int width, int height, char *data)
574 {
575 	int i, ret;
576 	char *cmd;
577 	cycles_t start_cycles, end_cycles;
578 	int bytes_sent = 0;
579 	int bytes_identical = 0;
580 	struct urb *urb;
581 	int aligned_x;
582 
583 	start_cycles = get_cycles();
584 
585 	aligned_x = DL_ALIGN_DOWN(x, sizeof(unsigned long));
586 	width = DL_ALIGN_UP(width + (x-aligned_x), sizeof(unsigned long));
587 	x = aligned_x;
588 
589 	if ((width <= 0) ||
590 	    (x + width > dlfb->info->var.xres) ||
591 	    (y + height > dlfb->info->var.yres))
592 		return -EINVAL;
593 
594 	if (!atomic_read(&dlfb->usb_active))
595 		return 0;
596 
597 	urb = dlfb_get_urb(dlfb);
598 	if (!urb)
599 		return 0;
600 	cmd = urb->transfer_buffer;
601 
602 	for (i = y; i < y + height ; i++) {
603 		const int line_offset = dlfb->info->fix.line_length * i;
604 		const int byte_offset = line_offset + (x * BPP);
605 
606 		if (dlfb_render_hline(dlfb, &urb,
607 				      (char *) dlfb->info->fix.smem_start,
608 				      &cmd, byte_offset, width * BPP,
609 				      &bytes_identical, &bytes_sent))
610 			goto error;
611 	}
612 
613 	if (cmd > (char *) urb->transfer_buffer) {
614 		/* Send partial buffer remaining before exiting */
615 		int len = cmd - (char *) urb->transfer_buffer;
616 		ret = dlfb_submit_urb(dlfb, urb, len);
617 		bytes_sent += len;
618 	} else
619 		dlfb_urb_completion(urb);
620 
621 error:
622 	atomic_add(bytes_sent, &dlfb->bytes_sent);
623 	atomic_add(bytes_identical, &dlfb->bytes_identical);
624 	atomic_add(width*height*2, &dlfb->bytes_rendered);
625 	end_cycles = get_cycles();
626 	atomic_add(((unsigned int) ((end_cycles - start_cycles)
627 		    >> 10)), /* Kcycles */
628 		   &dlfb->cpu_kcycles_used);
629 
630 	return 0;
631 }
632 
633 /*
634  * Path triggered by usermode clients who write to filesystem
635  * e.g. cat filename > /dev/fb1
636  * Not used by X Windows or text-mode console. But useful for testing.
637  * Slow because of extra copy and we must assume all pixels dirty.
638  */
639 static ssize_t dlfb_ops_write(struct fb_info *info, const char __user *buf,
640 			  size_t count, loff_t *ppos)
641 {
642 	ssize_t result;
643 	struct dlfb_data *dlfb = info->par;
644 	u32 offset = (u32) *ppos;
645 
646 	result = fb_sys_write(info, buf, count, ppos);
647 
648 	if (result > 0) {
649 		int start = max((int)(offset / info->fix.line_length), 0);
650 		int lines = min((u32)((result / info->fix.line_length) + 1),
651 				(u32)info->var.yres);
652 
653 		dlfb_handle_damage(dlfb, 0, start, info->var.xres,
654 			lines, info->screen_base);
655 	}
656 
657 	return result;
658 }
659 
660 /* hardware has native COPY command (see libdlo), but not worth it for fbcon */
661 static void dlfb_ops_copyarea(struct fb_info *info,
662 				const struct fb_copyarea *area)
663 {
664 
665 	struct dlfb_data *dlfb = info->par;
666 
667 	sys_copyarea(info, area);
668 
669 	dlfb_handle_damage(dlfb, area->dx, area->dy,
670 			area->width, area->height, info->screen_base);
671 }
672 
673 static void dlfb_ops_imageblit(struct fb_info *info,
674 				const struct fb_image *image)
675 {
676 	struct dlfb_data *dlfb = info->par;
677 
678 	sys_imageblit(info, image);
679 
680 	dlfb_handle_damage(dlfb, image->dx, image->dy,
681 			image->width, image->height, info->screen_base);
682 }
683 
684 static void dlfb_ops_fillrect(struct fb_info *info,
685 			  const struct fb_fillrect *rect)
686 {
687 	struct dlfb_data *dlfb = info->par;
688 
689 	sys_fillrect(info, rect);
690 
691 	dlfb_handle_damage(dlfb, rect->dx, rect->dy, rect->width,
692 			      rect->height, info->screen_base);
693 }
694 
695 /*
696  * NOTE: fb_defio.c is holding info->fbdefio.mutex
697  *   Touching ANY framebuffer memory that triggers a page fault
698  *   in fb_defio will cause a deadlock, when it also tries to
699  *   grab the same mutex.
700  */
701 static void dlfb_dpy_deferred_io(struct fb_info *info,
702 				struct list_head *pagelist)
703 {
704 	struct page *cur;
705 	struct fb_deferred_io *fbdefio = info->fbdefio;
706 	struct dlfb_data *dlfb = info->par;
707 	struct urb *urb;
708 	char *cmd;
709 	cycles_t start_cycles, end_cycles;
710 	int bytes_sent = 0;
711 	int bytes_identical = 0;
712 	int bytes_rendered = 0;
713 
714 	if (!fb_defio)
715 		return;
716 
717 	if (!atomic_read(&dlfb->usb_active))
718 		return;
719 
720 	start_cycles = get_cycles();
721 
722 	urb = dlfb_get_urb(dlfb);
723 	if (!urb)
724 		return;
725 
726 	cmd = urb->transfer_buffer;
727 
728 	/* walk the written page list and render each to device */
729 	list_for_each_entry(cur, &fbdefio->pagelist, lru) {
730 
731 		if (dlfb_render_hline(dlfb, &urb, (char *) info->fix.smem_start,
732 				  &cmd, cur->index << PAGE_SHIFT,
733 				  PAGE_SIZE, &bytes_identical, &bytes_sent))
734 			goto error;
735 		bytes_rendered += PAGE_SIZE;
736 	}
737 
738 	if (cmd > (char *) urb->transfer_buffer) {
739 		/* Send partial buffer remaining before exiting */
740 		int len = cmd - (char *) urb->transfer_buffer;
741 		dlfb_submit_urb(dlfb, urb, len);
742 		bytes_sent += len;
743 	} else
744 		dlfb_urb_completion(urb);
745 
746 error:
747 	atomic_add(bytes_sent, &dlfb->bytes_sent);
748 	atomic_add(bytes_identical, &dlfb->bytes_identical);
749 	atomic_add(bytes_rendered, &dlfb->bytes_rendered);
750 	end_cycles = get_cycles();
751 	atomic_add(((unsigned int) ((end_cycles - start_cycles)
752 		    >> 10)), /* Kcycles */
753 		   &dlfb->cpu_kcycles_used);
754 }
755 
756 static int dlfb_get_edid(struct dlfb_data *dlfb, char *edid, int len)
757 {
758 	int i, ret;
759 	char *rbuf;
760 
761 	rbuf = kmalloc(2, GFP_KERNEL);
762 	if (!rbuf)
763 		return 0;
764 
765 	for (i = 0; i < len; i++) {
766 		ret = usb_control_msg(dlfb->udev,
767 				      usb_rcvctrlpipe(dlfb->udev, 0), 0x02,
768 				      (0x80 | (0x02 << 5)), i << 8, 0xA1,
769 				      rbuf, 2, USB_CTRL_GET_TIMEOUT);
770 		if (ret < 2) {
771 			dev_err(&dlfb->udev->dev,
772 				"Read EDID byte %d failed: %d\n", i, ret);
773 			i--;
774 			break;
775 		}
776 		edid[i] = rbuf[1];
777 	}
778 
779 	kfree(rbuf);
780 
781 	return i;
782 }
783 
784 static int dlfb_ops_ioctl(struct fb_info *info, unsigned int cmd,
785 				unsigned long arg)
786 {
787 
788 	struct dlfb_data *dlfb = info->par;
789 
790 	if (!atomic_read(&dlfb->usb_active))
791 		return 0;
792 
793 	/* TODO: Update X server to get this from sysfs instead */
794 	if (cmd == DLFB_IOCTL_RETURN_EDID) {
795 		void __user *edid = (void __user *)arg;
796 		if (copy_to_user(edid, dlfb->edid, dlfb->edid_size))
797 			return -EFAULT;
798 		return 0;
799 	}
800 
801 	/* TODO: Help propose a standard fb.h ioctl to report mmap damage */
802 	if (cmd == DLFB_IOCTL_REPORT_DAMAGE) {
803 		struct dloarea area;
804 
805 		if (copy_from_user(&area, (void __user *)arg,
806 				  sizeof(struct dloarea)))
807 			return -EFAULT;
808 
809 		/*
810 		 * If we have a damage-aware client, turn fb_defio "off"
811 		 * To avoid perf imact of unnecessary page fault handling.
812 		 * Done by resetting the delay for this fb_info to a very
813 		 * long period. Pages will become writable and stay that way.
814 		 * Reset to normal value when all clients have closed this fb.
815 		 */
816 		if (info->fbdefio)
817 			info->fbdefio->delay = DL_DEFIO_WRITE_DISABLE;
818 
819 		if (area.x < 0)
820 			area.x = 0;
821 
822 		if (area.x > info->var.xres)
823 			area.x = info->var.xres;
824 
825 		if (area.y < 0)
826 			area.y = 0;
827 
828 		if (area.y > info->var.yres)
829 			area.y = info->var.yres;
830 
831 		dlfb_handle_damage(dlfb, area.x, area.y, area.w, area.h,
832 			   info->screen_base);
833 	}
834 
835 	return 0;
836 }
837 
838 /* taken from vesafb */
839 static int
840 dlfb_ops_setcolreg(unsigned regno, unsigned red, unsigned green,
841 	       unsigned blue, unsigned transp, struct fb_info *info)
842 {
843 	int err = 0;
844 
845 	if (regno >= info->cmap.len)
846 		return 1;
847 
848 	if (regno < 16) {
849 		if (info->var.red.offset == 10) {
850 			/* 1:5:5:5 */
851 			((u32 *) (info->pseudo_palette))[regno] =
852 			    ((red & 0xf800) >> 1) |
853 			    ((green & 0xf800) >> 6) | ((blue & 0xf800) >> 11);
854 		} else {
855 			/* 0:5:6:5 */
856 			((u32 *) (info->pseudo_palette))[regno] =
857 			    ((red & 0xf800)) |
858 			    ((green & 0xfc00) >> 5) | ((blue & 0xf800) >> 11);
859 		}
860 	}
861 
862 	return err;
863 }
864 
865 /*
866  * It's common for several clients to have framebuffer open simultaneously.
867  * e.g. both fbcon and X. Makes things interesting.
868  * Assumes caller is holding info->lock (for open and release at least)
869  */
870 static int dlfb_ops_open(struct fb_info *info, int user)
871 {
872 	struct dlfb_data *dlfb = info->par;
873 
874 	/*
875 	 * fbcon aggressively connects to first framebuffer it finds,
876 	 * preventing other clients (X) from working properly. Usually
877 	 * not what the user wants. Fail by default with option to enable.
878 	 */
879 	if ((user == 0) && (!console))
880 		return -EBUSY;
881 
882 	/* If the USB device is gone, we don't accept new opens */
883 	if (dlfb->virtualized)
884 		return -ENODEV;
885 
886 	dlfb->fb_count++;
887 
888 	kref_get(&dlfb->kref);
889 
890 	if (fb_defio && (info->fbdefio == NULL)) {
891 		/* enable defio at last moment if not disabled by client */
892 
893 		struct fb_deferred_io *fbdefio;
894 
895 		fbdefio = kzalloc(sizeof(struct fb_deferred_io), GFP_KERNEL);
896 
897 		if (fbdefio) {
898 			fbdefio->delay = DL_DEFIO_WRITE_DELAY;
899 			fbdefio->deferred_io = dlfb_dpy_deferred_io;
900 		}
901 
902 		info->fbdefio = fbdefio;
903 		fb_deferred_io_init(info);
904 	}
905 
906 	dev_dbg(info->dev, "open, user=%d fb_info=%p count=%d\n",
907 		user, info, dlfb->fb_count);
908 
909 	return 0;
910 }
911 
912 /*
913  * Called when all client interfaces to start transactions have been disabled,
914  * and all references to our device instance (dlfb_data) are released.
915  * Every transaction must have a reference, so we know are fully spun down
916  */
917 static void dlfb_free(struct kref *kref)
918 {
919 	struct dlfb_data *dlfb = container_of(kref, struct dlfb_data, kref);
920 
921 	vfree(dlfb->backing_buffer);
922 	kfree(dlfb->edid);
923 	kfree(dlfb);
924 }
925 
926 static void dlfb_release_urb_work(struct work_struct *work)
927 {
928 	struct urb_node *unode = container_of(work, struct urb_node,
929 					      release_urb_work.work);
930 
931 	up(&unode->dlfb->urbs.limit_sem);
932 }
933 
934 static void dlfb_free_framebuffer(struct dlfb_data *dlfb)
935 {
936 	struct fb_info *info = dlfb->info;
937 
938 	if (info) {
939 		unregister_framebuffer(info);
940 
941 		if (info->cmap.len != 0)
942 			fb_dealloc_cmap(&info->cmap);
943 		if (info->monspecs.modedb)
944 			fb_destroy_modedb(info->monspecs.modedb);
945 		vfree(info->screen_base);
946 
947 		fb_destroy_modelist(&info->modelist);
948 
949 		dlfb->info = NULL;
950 
951 		/* Assume info structure is freed after this point */
952 		framebuffer_release(info);
953 	}
954 
955 	/* ref taken in probe() as part of registering framebfufer */
956 	kref_put(&dlfb->kref, dlfb_free);
957 }
958 
959 static void dlfb_free_framebuffer_work(struct work_struct *work)
960 {
961 	struct dlfb_data *dlfb = container_of(work, struct dlfb_data,
962 					     free_framebuffer_work.work);
963 	dlfb_free_framebuffer(dlfb);
964 }
965 /*
966  * Assumes caller is holding info->lock mutex (for open and release at least)
967  */
968 static int dlfb_ops_release(struct fb_info *info, int user)
969 {
970 	struct dlfb_data *dlfb = info->par;
971 
972 	dlfb->fb_count--;
973 
974 	/* We can't free fb_info here - fbmem will touch it when we return */
975 	if (dlfb->virtualized && (dlfb->fb_count == 0))
976 		schedule_delayed_work(&dlfb->free_framebuffer_work, HZ);
977 
978 	if ((dlfb->fb_count == 0) && (info->fbdefio)) {
979 		fb_deferred_io_cleanup(info);
980 		kfree(info->fbdefio);
981 		info->fbdefio = NULL;
982 		info->fbops->fb_mmap = dlfb_ops_mmap;
983 	}
984 
985 	dev_dbg(info->dev, "release, user=%d count=%d\n", user, dlfb->fb_count);
986 
987 	kref_put(&dlfb->kref, dlfb_free);
988 
989 	return 0;
990 }
991 
992 /*
993  * Check whether a video mode is supported by the DisplayLink chip
994  * We start from monitor's modes, so don't need to filter that here
995  */
996 static int dlfb_is_valid_mode(struct fb_videomode *mode, struct dlfb_data *dlfb)
997 {
998 	if (mode->xres * mode->yres > dlfb->sku_pixel_limit)
999 		return 0;
1000 
1001 	return 1;
1002 }
1003 
1004 static void dlfb_var_color_format(struct fb_var_screeninfo *var)
1005 {
1006 	const struct fb_bitfield red = { 11, 5, 0 };
1007 	const struct fb_bitfield green = { 5, 6, 0 };
1008 	const struct fb_bitfield blue = { 0, 5, 0 };
1009 
1010 	var->bits_per_pixel = 16;
1011 	var->red = red;
1012 	var->green = green;
1013 	var->blue = blue;
1014 }
1015 
1016 static int dlfb_ops_check_var(struct fb_var_screeninfo *var,
1017 				struct fb_info *info)
1018 {
1019 	struct fb_videomode mode;
1020 	struct dlfb_data *dlfb = info->par;
1021 
1022 	/* TODO: support dynamically changing framebuffer size */
1023 	if ((var->xres * var->yres * 2) > info->fix.smem_len)
1024 		return -EINVAL;
1025 
1026 	/* set device-specific elements of var unrelated to mode */
1027 	dlfb_var_color_format(var);
1028 
1029 	fb_var_to_videomode(&mode, var);
1030 
1031 	if (!dlfb_is_valid_mode(&mode, dlfb))
1032 		return -EINVAL;
1033 
1034 	return 0;
1035 }
1036 
1037 static int dlfb_ops_set_par(struct fb_info *info)
1038 {
1039 	struct dlfb_data *dlfb = info->par;
1040 	int result;
1041 	u16 *pix_framebuffer;
1042 	int i;
1043 
1044 	result = dlfb_set_video_mode(dlfb, &info->var);
1045 
1046 	if ((result == 0) && (dlfb->fb_count == 0)) {
1047 
1048 		/* paint greenscreen */
1049 
1050 		pix_framebuffer = (u16 *) info->screen_base;
1051 		for (i = 0; i < info->fix.smem_len / 2; i++)
1052 			pix_framebuffer[i] = 0x37e6;
1053 
1054 		dlfb_handle_damage(dlfb, 0, 0, info->var.xres, info->var.yres,
1055 				   info->screen_base);
1056 	}
1057 
1058 	return result;
1059 }
1060 
1061 /* To fonzi the jukebox (e.g. make blanking changes take effect) */
1062 static char *dlfb_dummy_render(char *buf)
1063 {
1064 	*buf++ = 0xAF;
1065 	*buf++ = 0x6A; /* copy */
1066 	*buf++ = 0x00; /* from address*/
1067 	*buf++ = 0x00;
1068 	*buf++ = 0x00;
1069 	*buf++ = 0x01; /* one pixel */
1070 	*buf++ = 0x00; /* to address */
1071 	*buf++ = 0x00;
1072 	*buf++ = 0x00;
1073 	return buf;
1074 }
1075 
1076 /*
1077  * In order to come back from full DPMS off, we need to set the mode again
1078  */
1079 static int dlfb_ops_blank(int blank_mode, struct fb_info *info)
1080 {
1081 	struct dlfb_data *dlfb = info->par;
1082 	char *bufptr;
1083 	struct urb *urb;
1084 
1085 	dev_dbg(info->dev, "blank, mode %d --> %d\n",
1086 		dlfb->blank_mode, blank_mode);
1087 
1088 	if ((dlfb->blank_mode == FB_BLANK_POWERDOWN) &&
1089 	    (blank_mode != FB_BLANK_POWERDOWN)) {
1090 
1091 		/* returning from powerdown requires a fresh modeset */
1092 		dlfb_set_video_mode(dlfb, &info->var);
1093 	}
1094 
1095 	urb = dlfb_get_urb(dlfb);
1096 	if (!urb)
1097 		return 0;
1098 
1099 	bufptr = (char *) urb->transfer_buffer;
1100 	bufptr = dlfb_vidreg_lock(bufptr);
1101 	bufptr = dlfb_blanking(bufptr, blank_mode);
1102 	bufptr = dlfb_vidreg_unlock(bufptr);
1103 
1104 	/* seems like a render op is needed to have blank change take effect */
1105 	bufptr = dlfb_dummy_render(bufptr);
1106 
1107 	dlfb_submit_urb(dlfb, urb, bufptr -
1108 			(char *) urb->transfer_buffer);
1109 
1110 	dlfb->blank_mode = blank_mode;
1111 
1112 	return 0;
1113 }
1114 
1115 static struct fb_ops dlfb_ops = {
1116 	.owner = THIS_MODULE,
1117 	.fb_read = fb_sys_read,
1118 	.fb_write = dlfb_ops_write,
1119 	.fb_setcolreg = dlfb_ops_setcolreg,
1120 	.fb_fillrect = dlfb_ops_fillrect,
1121 	.fb_copyarea = dlfb_ops_copyarea,
1122 	.fb_imageblit = dlfb_ops_imageblit,
1123 	.fb_mmap = dlfb_ops_mmap,
1124 	.fb_ioctl = dlfb_ops_ioctl,
1125 	.fb_open = dlfb_ops_open,
1126 	.fb_release = dlfb_ops_release,
1127 	.fb_blank = dlfb_ops_blank,
1128 	.fb_check_var = dlfb_ops_check_var,
1129 	.fb_set_par = dlfb_ops_set_par,
1130 };
1131 
1132 
1133 /*
1134  * Assumes &info->lock held by caller
1135  * Assumes no active clients have framebuffer open
1136  */
1137 static int dlfb_realloc_framebuffer(struct dlfb_data *dlfb, struct fb_info *info)
1138 {
1139 	int retval = -ENOMEM;
1140 	int old_len = info->fix.smem_len;
1141 	int new_len;
1142 	unsigned char *old_fb = info->screen_base;
1143 	unsigned char *new_fb;
1144 	unsigned char *new_back = NULL;
1145 
1146 	new_len = info->fix.line_length * info->var.yres;
1147 
1148 	if (PAGE_ALIGN(new_len) > old_len) {
1149 		/*
1150 		 * Alloc system memory for virtual framebuffer
1151 		 */
1152 		new_fb = vmalloc(new_len);
1153 		if (!new_fb) {
1154 			dev_err(info->dev, "Virtual framebuffer alloc failed\n");
1155 			goto error;
1156 		}
1157 
1158 		if (info->screen_base) {
1159 			memcpy(new_fb, old_fb, old_len);
1160 			vfree(info->screen_base);
1161 		}
1162 
1163 		info->screen_base = new_fb;
1164 		info->fix.smem_len = PAGE_ALIGN(new_len);
1165 		info->fix.smem_start = (unsigned long) new_fb;
1166 		info->flags = udlfb_info_flags;
1167 
1168 		/*
1169 		 * Second framebuffer copy to mirror the framebuffer state
1170 		 * on the physical USB device. We can function without this.
1171 		 * But with imperfect damage info we may send pixels over USB
1172 		 * that were, in fact, unchanged - wasting limited USB bandwidth
1173 		 */
1174 		if (shadow)
1175 			new_back = vzalloc(new_len);
1176 		if (!new_back)
1177 			dev_info(info->dev,
1178 				 "No shadow/backing buffer allocated\n");
1179 		else {
1180 			vfree(dlfb->backing_buffer);
1181 			dlfb->backing_buffer = new_back;
1182 		}
1183 	}
1184 
1185 	retval = 0;
1186 
1187 error:
1188 	return retval;
1189 }
1190 
1191 /*
1192  * 1) Get EDID from hw, or use sw default
1193  * 2) Parse into various fb_info structs
1194  * 3) Allocate virtual framebuffer memory to back highest res mode
1195  *
1196  * Parses EDID into three places used by various parts of fbdev:
1197  * fb_var_screeninfo contains the timing of the monitor's preferred mode
1198  * fb_info.monspecs is full parsed EDID info, including monspecs.modedb
1199  * fb_info.modelist is a linked list of all monitor & VESA modes which work
1200  *
1201  * If EDID is not readable/valid, then modelist is all VESA modes,
1202  * monspecs is NULL, and fb_var_screeninfo is set to safe VESA mode
1203  * Returns 0 if successful
1204  */
1205 static int dlfb_setup_modes(struct dlfb_data *dlfb,
1206 			   struct fb_info *info,
1207 			   char *default_edid, size_t default_edid_size)
1208 {
1209 	char *edid;
1210 	int i, result = 0, tries = 3;
1211 	struct device *dev = info->device;
1212 	struct fb_videomode *mode;
1213 	const struct fb_videomode *default_vmode = NULL;
1214 
1215 	if (info->dev) {
1216 		/* only use mutex if info has been registered */
1217 		mutex_lock(&info->lock);
1218 		/* parent device is used otherwise */
1219 		dev = info->dev;
1220 	}
1221 
1222 	edid = kmalloc(EDID_LENGTH, GFP_KERNEL);
1223 	if (!edid) {
1224 		result = -ENOMEM;
1225 		goto error;
1226 	}
1227 
1228 	fb_destroy_modelist(&info->modelist);
1229 	memset(&info->monspecs, 0, sizeof(info->monspecs));
1230 
1231 	/*
1232 	 * Try to (re)read EDID from hardware first
1233 	 * EDID data may return, but not parse as valid
1234 	 * Try again a few times, in case of e.g. analog cable noise
1235 	 */
1236 	while (tries--) {
1237 
1238 		i = dlfb_get_edid(dlfb, edid, EDID_LENGTH);
1239 
1240 		if (i >= EDID_LENGTH)
1241 			fb_edid_to_monspecs(edid, &info->monspecs);
1242 
1243 		if (info->monspecs.modedb_len > 0) {
1244 			dlfb->edid = edid;
1245 			dlfb->edid_size = i;
1246 			break;
1247 		}
1248 	}
1249 
1250 	/* If that fails, use a previously returned EDID if available */
1251 	if (info->monspecs.modedb_len == 0) {
1252 		dev_err(dev, "Unable to get valid EDID from device/display\n");
1253 
1254 		if (dlfb->edid) {
1255 			fb_edid_to_monspecs(dlfb->edid, &info->monspecs);
1256 			if (info->monspecs.modedb_len > 0)
1257 				dev_err(dev, "Using previously queried EDID\n");
1258 		}
1259 	}
1260 
1261 	/* If that fails, use the default EDID we were handed */
1262 	if (info->monspecs.modedb_len == 0) {
1263 		if (default_edid_size >= EDID_LENGTH) {
1264 			fb_edid_to_monspecs(default_edid, &info->monspecs);
1265 			if (info->monspecs.modedb_len > 0) {
1266 				memcpy(edid, default_edid, default_edid_size);
1267 				dlfb->edid = edid;
1268 				dlfb->edid_size = default_edid_size;
1269 				dev_err(dev, "Using default/backup EDID\n");
1270 			}
1271 		}
1272 	}
1273 
1274 	/* If we've got modes, let's pick a best default mode */
1275 	if (info->monspecs.modedb_len > 0) {
1276 
1277 		for (i = 0; i < info->monspecs.modedb_len; i++) {
1278 			mode = &info->monspecs.modedb[i];
1279 			if (dlfb_is_valid_mode(mode, dlfb)) {
1280 				fb_add_videomode(mode, &info->modelist);
1281 			} else {
1282 				dev_dbg(dev, "Specified mode %dx%d too big\n",
1283 					mode->xres, mode->yres);
1284 				if (i == 0)
1285 					/* if we've removed top/best mode */
1286 					info->monspecs.misc
1287 						&= ~FB_MISC_1ST_DETAIL;
1288 			}
1289 		}
1290 
1291 		default_vmode = fb_find_best_display(&info->monspecs,
1292 						     &info->modelist);
1293 	}
1294 
1295 	/* If everything else has failed, fall back to safe default mode */
1296 	if (default_vmode == NULL) {
1297 
1298 		struct fb_videomode fb_vmode = {0};
1299 
1300 		/*
1301 		 * Add the standard VESA modes to our modelist
1302 		 * Since we don't have EDID, there may be modes that
1303 		 * overspec monitor and/or are incorrect aspect ratio, etc.
1304 		 * But at least the user has a chance to choose
1305 		 */
1306 		for (i = 0; i < VESA_MODEDB_SIZE; i++) {
1307 			mode = (struct fb_videomode *)&vesa_modes[i];
1308 			if (dlfb_is_valid_mode(mode, dlfb))
1309 				fb_add_videomode(mode, &info->modelist);
1310 			else
1311 				dev_dbg(dev, "VESA mode %dx%d too big\n",
1312 					mode->xres, mode->yres);
1313 		}
1314 
1315 		/*
1316 		 * default to resolution safe for projectors
1317 		 * (since they are most common case without EDID)
1318 		 */
1319 		fb_vmode.xres = 800;
1320 		fb_vmode.yres = 600;
1321 		fb_vmode.refresh = 60;
1322 		default_vmode = fb_find_nearest_mode(&fb_vmode,
1323 						     &info->modelist);
1324 	}
1325 
1326 	/* If we have good mode and no active clients*/
1327 	if ((default_vmode != NULL) && (dlfb->fb_count == 0)) {
1328 
1329 		fb_videomode_to_var(&info->var, default_vmode);
1330 		dlfb_var_color_format(&info->var);
1331 
1332 		/*
1333 		 * with mode size info, we can now alloc our framebuffer.
1334 		 */
1335 		memcpy(&info->fix, &dlfb_fix, sizeof(dlfb_fix));
1336 		info->fix.line_length = info->var.xres *
1337 			(info->var.bits_per_pixel / 8);
1338 
1339 		result = dlfb_realloc_framebuffer(dlfb, info);
1340 
1341 	} else
1342 		result = -EINVAL;
1343 
1344 error:
1345 	if (edid && (dlfb->edid != edid))
1346 		kfree(edid);
1347 
1348 	if (info->dev)
1349 		mutex_unlock(&info->lock);
1350 
1351 	return result;
1352 }
1353 
1354 static ssize_t metrics_bytes_rendered_show(struct device *fbdev,
1355 				   struct device_attribute *a, char *buf) {
1356 	struct fb_info *fb_info = dev_get_drvdata(fbdev);
1357 	struct dlfb_data *dlfb = fb_info->par;
1358 	return snprintf(buf, PAGE_SIZE, "%u\n",
1359 			atomic_read(&dlfb->bytes_rendered));
1360 }
1361 
1362 static ssize_t metrics_bytes_identical_show(struct device *fbdev,
1363 				   struct device_attribute *a, char *buf) {
1364 	struct fb_info *fb_info = dev_get_drvdata(fbdev);
1365 	struct dlfb_data *dlfb = fb_info->par;
1366 	return snprintf(buf, PAGE_SIZE, "%u\n",
1367 			atomic_read(&dlfb->bytes_identical));
1368 }
1369 
1370 static ssize_t metrics_bytes_sent_show(struct device *fbdev,
1371 				   struct device_attribute *a, char *buf) {
1372 	struct fb_info *fb_info = dev_get_drvdata(fbdev);
1373 	struct dlfb_data *dlfb = fb_info->par;
1374 	return snprintf(buf, PAGE_SIZE, "%u\n",
1375 			atomic_read(&dlfb->bytes_sent));
1376 }
1377 
1378 static ssize_t metrics_cpu_kcycles_used_show(struct device *fbdev,
1379 				   struct device_attribute *a, char *buf) {
1380 	struct fb_info *fb_info = dev_get_drvdata(fbdev);
1381 	struct dlfb_data *dlfb = fb_info->par;
1382 	return snprintf(buf, PAGE_SIZE, "%u\n",
1383 			atomic_read(&dlfb->cpu_kcycles_used));
1384 }
1385 
1386 static ssize_t edid_show(
1387 			struct file *filp,
1388 			struct kobject *kobj, struct bin_attribute *a,
1389 			 char *buf, loff_t off, size_t count) {
1390 	struct device *fbdev = container_of(kobj, struct device, kobj);
1391 	struct fb_info *fb_info = dev_get_drvdata(fbdev);
1392 	struct dlfb_data *dlfb = fb_info->par;
1393 
1394 	if (dlfb->edid == NULL)
1395 		return 0;
1396 
1397 	if ((off >= dlfb->edid_size) || (count > dlfb->edid_size))
1398 		return 0;
1399 
1400 	if (off + count > dlfb->edid_size)
1401 		count = dlfb->edid_size - off;
1402 
1403 	memcpy(buf, dlfb->edid, count);
1404 
1405 	return count;
1406 }
1407 
1408 static ssize_t edid_store(
1409 			struct file *filp,
1410 			struct kobject *kobj, struct bin_attribute *a,
1411 			char *src, loff_t src_off, size_t src_size) {
1412 	struct device *fbdev = container_of(kobj, struct device, kobj);
1413 	struct fb_info *fb_info = dev_get_drvdata(fbdev);
1414 	struct dlfb_data *dlfb = fb_info->par;
1415 	int ret;
1416 
1417 	/* We only support write of entire EDID at once, no offset*/
1418 	if ((src_size != EDID_LENGTH) || (src_off != 0))
1419 		return -EINVAL;
1420 
1421 	ret = dlfb_setup_modes(dlfb, fb_info, src, src_size);
1422 	if (ret)
1423 		return ret;
1424 
1425 	if (!dlfb->edid || memcmp(src, dlfb->edid, src_size))
1426 		return -EINVAL;
1427 
1428 	dlfb_ops_set_par(fb_info);
1429 	return src_size;
1430 }
1431 
1432 static ssize_t metrics_reset_store(struct device *fbdev,
1433 			   struct device_attribute *attr,
1434 			   const char *buf, size_t count)
1435 {
1436 	struct fb_info *fb_info = dev_get_drvdata(fbdev);
1437 	struct dlfb_data *dlfb = fb_info->par;
1438 
1439 	atomic_set(&dlfb->bytes_rendered, 0);
1440 	atomic_set(&dlfb->bytes_identical, 0);
1441 	atomic_set(&dlfb->bytes_sent, 0);
1442 	atomic_set(&dlfb->cpu_kcycles_used, 0);
1443 
1444 	return count;
1445 }
1446 
1447 static const struct bin_attribute edid_attr = {
1448 	.attr.name = "edid",
1449 	.attr.mode = 0666,
1450 	.size = EDID_LENGTH,
1451 	.read = edid_show,
1452 	.write = edid_store
1453 };
1454 
1455 static const struct device_attribute fb_device_attrs[] = {
1456 	__ATTR_RO(metrics_bytes_rendered),
1457 	__ATTR_RO(metrics_bytes_identical),
1458 	__ATTR_RO(metrics_bytes_sent),
1459 	__ATTR_RO(metrics_cpu_kcycles_used),
1460 	__ATTR(metrics_reset, S_IWUSR, NULL, metrics_reset_store),
1461 };
1462 
1463 /*
1464  * This is necessary before we can communicate with the display controller.
1465  */
1466 static int dlfb_select_std_channel(struct dlfb_data *dlfb)
1467 {
1468 	int ret;
1469 	void *buf;
1470 	static const u8 set_def_chn[] = {
1471 				0x57, 0xCD, 0xDC, 0xA7,
1472 				0x1C, 0x88, 0x5E, 0x15,
1473 				0x60, 0xFE, 0xC6, 0x97,
1474 				0x16, 0x3D, 0x47, 0xF2  };
1475 
1476 	buf = kmemdup(set_def_chn, sizeof(set_def_chn), GFP_KERNEL);
1477 
1478 	if (!buf)
1479 		return -ENOMEM;
1480 
1481 	ret = usb_control_msg(dlfb->udev, usb_sndctrlpipe(dlfb->udev, 0),
1482 			NR_USB_REQUEST_CHANNEL,
1483 			(USB_DIR_OUT | USB_TYPE_VENDOR), 0, 0,
1484 			buf, sizeof(set_def_chn), USB_CTRL_SET_TIMEOUT);
1485 
1486 	kfree(buf);
1487 
1488 	return ret;
1489 }
1490 
1491 static int dlfb_parse_vendor_descriptor(struct dlfb_data *dlfb,
1492 					struct usb_interface *intf)
1493 {
1494 	char *desc;
1495 	char *buf;
1496 	char *desc_end;
1497 	int total_len;
1498 
1499 	buf = kzalloc(MAX_VENDOR_DESCRIPTOR_SIZE, GFP_KERNEL);
1500 	if (!buf)
1501 		return false;
1502 	desc = buf;
1503 
1504 	total_len = usb_get_descriptor(interface_to_usbdev(intf),
1505 					0x5f, /* vendor specific */
1506 					0, desc, MAX_VENDOR_DESCRIPTOR_SIZE);
1507 
1508 	/* if not found, look in configuration descriptor */
1509 	if (total_len < 0) {
1510 		if (0 == usb_get_extra_descriptor(intf->cur_altsetting,
1511 			0x5f, &desc))
1512 			total_len = (int) desc[0];
1513 	}
1514 
1515 	if (total_len > 5) {
1516 		dev_info(&intf->dev,
1517 			 "vendor descriptor length: %d data: %11ph\n",
1518 			 total_len, desc);
1519 
1520 		if ((desc[0] != total_len) || /* descriptor length */
1521 		    (desc[1] != 0x5f) ||   /* vendor descriptor type */
1522 		    (desc[2] != 0x01) ||   /* version (2 bytes) */
1523 		    (desc[3] != 0x00) ||
1524 		    (desc[4] != total_len - 2)) /* length after type */
1525 			goto unrecognized;
1526 
1527 		desc_end = desc + total_len;
1528 		desc += 5; /* the fixed header we've already parsed */
1529 
1530 		while (desc < desc_end) {
1531 			u8 length;
1532 			u16 key;
1533 
1534 			key = le16_to_cpu(*((u16 *) desc));
1535 			desc += sizeof(u16);
1536 			length = *desc;
1537 			desc++;
1538 
1539 			switch (key) {
1540 			case 0x0200: { /* max_area */
1541 				u32 max_area;
1542 				max_area = le32_to_cpu(*((u32 *)desc));
1543 				dev_warn(&intf->dev,
1544 					 "DL chip limited to %d pixel modes\n",
1545 					 max_area);
1546 				dlfb->sku_pixel_limit = max_area;
1547 				break;
1548 			}
1549 			default:
1550 				break;
1551 			}
1552 			desc += length;
1553 		}
1554 	} else {
1555 		dev_info(&intf->dev, "vendor descriptor not available (%d)\n",
1556 			 total_len);
1557 	}
1558 
1559 	goto success;
1560 
1561 unrecognized:
1562 	/* allow udlfb to load for now even if firmware unrecognized */
1563 	dev_err(&intf->dev, "Unrecognized vendor firmware descriptor\n");
1564 
1565 success:
1566 	kfree(buf);
1567 	return true;
1568 }
1569 
1570 static void dlfb_init_framebuffer_work(struct work_struct *work);
1571 
1572 static int dlfb_usb_probe(struct usb_interface *intf,
1573 			  const struct usb_device_id *id)
1574 {
1575 	struct dlfb_data *dlfb;
1576 	int retval = -ENOMEM;
1577 	struct usb_device *usbdev = interface_to_usbdev(intf);
1578 
1579 	/* usb initialization */
1580 	dlfb = kzalloc(sizeof(*dlfb), GFP_KERNEL);
1581 	if (!dlfb) {
1582 		dev_err(&intf->dev, "%s: failed to allocate dlfb\n", __func__);
1583 		goto error;
1584 	}
1585 
1586 	kref_init(&dlfb->kref); /* matching kref_put in usb .disconnect fn */
1587 
1588 	dlfb->udev = usbdev;
1589 	usb_set_intfdata(intf, dlfb);
1590 
1591 	dev_dbg(&intf->dev, "console enable=%d\n", console);
1592 	dev_dbg(&intf->dev, "fb_defio enable=%d\n", fb_defio);
1593 	dev_dbg(&intf->dev, "shadow enable=%d\n", shadow);
1594 
1595 	dlfb->sku_pixel_limit = 2048 * 1152; /* default to maximum */
1596 
1597 	if (!dlfb_parse_vendor_descriptor(dlfb, intf)) {
1598 		dev_err(&intf->dev,
1599 			"firmware not recognized, incompatible device?\n");
1600 		goto error;
1601 	}
1602 
1603 	if (pixel_limit) {
1604 		dev_warn(&intf->dev,
1605 			 "DL chip limit of %d overridden to %d\n",
1606 			 dlfb->sku_pixel_limit, pixel_limit);
1607 		dlfb->sku_pixel_limit = pixel_limit;
1608 	}
1609 
1610 
1611 	if (!dlfb_alloc_urb_list(dlfb, WRITES_IN_FLIGHT, MAX_TRANSFER)) {
1612 		retval = -ENOMEM;
1613 		dev_err(&intf->dev, "unable to allocate urb list\n");
1614 		goto error;
1615 	}
1616 
1617 	kref_get(&dlfb->kref); /* matching kref_put in free_framebuffer_work */
1618 
1619 	/* We don't register a new USB class. Our client interface is dlfbev */
1620 
1621 	/* Workitem keep things fast & simple during USB enumeration */
1622 	INIT_DELAYED_WORK(&dlfb->init_framebuffer_work,
1623 			  dlfb_init_framebuffer_work);
1624 	schedule_delayed_work(&dlfb->init_framebuffer_work, 0);
1625 
1626 	return 0;
1627 
1628 error:
1629 	if (dlfb) {
1630 
1631 		kref_put(&dlfb->kref, dlfb_free); /* last ref from kref_init */
1632 
1633 		/* dev has been deallocated. Do not dereference */
1634 	}
1635 
1636 	return retval;
1637 }
1638 
1639 static void dlfb_init_framebuffer_work(struct work_struct *work)
1640 {
1641 	int i, retval;
1642 	struct fb_info *info;
1643 	const struct device_attribute *attr;
1644 	struct dlfb_data *dlfb = container_of(work, struct dlfb_data,
1645 					     init_framebuffer_work.work);
1646 
1647 	/* allocates framebuffer driver structure, not framebuffer memory */
1648 	info = framebuffer_alloc(0, &dlfb->udev->dev);
1649 	if (!info) {
1650 		dev_err(&dlfb->udev->dev, "framebuffer_alloc failed\n");
1651 		goto error;
1652 	}
1653 
1654 	dlfb->info = info;
1655 	info->par = dlfb;
1656 	info->pseudo_palette = dlfb->pseudo_palette;
1657 	info->fbops = &dlfb_ops;
1658 
1659 	retval = fb_alloc_cmap(&info->cmap, 256, 0);
1660 	if (retval < 0) {
1661 		dev_err(info->device, "cmap allocation failed: %d\n", retval);
1662 		goto error;
1663 	}
1664 
1665 	INIT_DELAYED_WORK(&dlfb->free_framebuffer_work,
1666 			  dlfb_free_framebuffer_work);
1667 
1668 	INIT_LIST_HEAD(&info->modelist);
1669 
1670 	retval = dlfb_setup_modes(dlfb, info, NULL, 0);
1671 	if (retval != 0) {
1672 		dev_err(info->device,
1673 			"unable to find common mode for display and adapter\n");
1674 		goto error;
1675 	}
1676 
1677 	/* ready to begin using device */
1678 
1679 	atomic_set(&dlfb->usb_active, 1);
1680 	dlfb_select_std_channel(dlfb);
1681 
1682 	dlfb_ops_check_var(&info->var, info);
1683 	dlfb_ops_set_par(info);
1684 
1685 	retval = register_framebuffer(info);
1686 	if (retval < 0) {
1687 		dev_err(info->device, "unable to register framebuffer: %d\n",
1688 			retval);
1689 		goto error;
1690 	}
1691 
1692 	for (i = 0; i < ARRAY_SIZE(fb_device_attrs); i++) {
1693 		attr = &fb_device_attrs[i];
1694 		retval = device_create_file(info->dev, attr);
1695 		if (retval)
1696 			dev_warn(info->device,
1697 				 "failed to create '%s' attribute: %d\n",
1698 				 attr->attr.name, retval);
1699 	}
1700 
1701 	retval = device_create_bin_file(info->dev, &edid_attr);
1702 	if (retval)
1703 		dev_warn(info->device, "failed to create '%s' attribute: %d\n",
1704 			 edid_attr.attr.name, retval);
1705 
1706 	dev_info(info->device,
1707 		 "%s is DisplayLink USB device (%dx%d, %dK framebuffer memory)\n",
1708 		 dev_name(info->dev), info->var.xres, info->var.yres,
1709 		 ((dlfb->backing_buffer) ?
1710 		 info->fix.smem_len * 2 : info->fix.smem_len) >> 10);
1711 	return;
1712 
1713 error:
1714 	dlfb_free_framebuffer(dlfb);
1715 }
1716 
1717 static void dlfb_usb_disconnect(struct usb_interface *intf)
1718 {
1719 	struct dlfb_data *dlfb;
1720 	struct fb_info *info;
1721 	int i;
1722 
1723 	dlfb = usb_get_intfdata(intf);
1724 	info = dlfb->info;
1725 
1726 	dev_dbg(&intf->dev, "USB disconnect starting\n");
1727 
1728 	/* we virtualize until all fb clients release. Then we free */
1729 	dlfb->virtualized = true;
1730 
1731 	/* When non-active we'll update virtual framebuffer, but no new urbs */
1732 	atomic_set(&dlfb->usb_active, 0);
1733 
1734 	/* this function will wait for all in-flight urbs to complete */
1735 	dlfb_free_urb_list(dlfb);
1736 
1737 	if (info) {
1738 		/* remove udlfb's sysfs interfaces */
1739 		for (i = 0; i < ARRAY_SIZE(fb_device_attrs); i++)
1740 			device_remove_file(info->dev, &fb_device_attrs[i]);
1741 		device_remove_bin_file(info->dev, &edid_attr);
1742 		unlink_framebuffer(info);
1743 	}
1744 
1745 	usb_set_intfdata(intf, NULL);
1746 	dlfb->udev = NULL;
1747 
1748 	/* if clients still have us open, will be freed on last close */
1749 	if (dlfb->fb_count == 0)
1750 		schedule_delayed_work(&dlfb->free_framebuffer_work, 0);
1751 
1752 	/* release reference taken by kref_init in probe() */
1753 	kref_put(&dlfb->kref, dlfb_free);
1754 
1755 	/* consider dlfb_data freed */
1756 }
1757 
1758 static struct usb_driver dlfb_driver = {
1759 	.name = "udlfb",
1760 	.probe = dlfb_usb_probe,
1761 	.disconnect = dlfb_usb_disconnect,
1762 	.id_table = id_table,
1763 };
1764 
1765 module_usb_driver(dlfb_driver);
1766 
1767 static void dlfb_urb_completion(struct urb *urb)
1768 {
1769 	struct urb_node *unode = urb->context;
1770 	struct dlfb_data *dlfb = unode->dlfb;
1771 	unsigned long flags;
1772 
1773 	switch (urb->status) {
1774 	case 0:
1775 		/* success */
1776 		break;
1777 	case -ECONNRESET:
1778 	case -ENOENT:
1779 	case -ESHUTDOWN:
1780 		/* sync/async unlink faults aren't errors */
1781 		break;
1782 	default:
1783 		dev_err(&dlfb->udev->dev,
1784 			"%s - nonzero write bulk status received: %d\n",
1785 			__func__, urb->status);
1786 		atomic_set(&dlfb->lost_pixels, 1);
1787 		break;
1788 	}
1789 
1790 	urb->transfer_buffer_length = dlfb->urbs.size; /* reset to actual */
1791 
1792 	spin_lock_irqsave(&dlfb->urbs.lock, flags);
1793 	list_add_tail(&unode->entry, &dlfb->urbs.list);
1794 	dlfb->urbs.available++;
1795 	spin_unlock_irqrestore(&dlfb->urbs.lock, flags);
1796 
1797 	/*
1798 	 * When using fb_defio, we deadlock if up() is called
1799 	 * while another is waiting. So queue to another process.
1800 	 */
1801 	if (fb_defio)
1802 		schedule_delayed_work(&unode->release_urb_work, 0);
1803 	else
1804 		up(&dlfb->urbs.limit_sem);
1805 }
1806 
1807 static void dlfb_free_urb_list(struct dlfb_data *dlfb)
1808 {
1809 	int count = dlfb->urbs.count;
1810 	struct list_head *node;
1811 	struct urb_node *unode;
1812 	struct urb *urb;
1813 	int ret;
1814 	unsigned long flags;
1815 
1816 	/* keep waiting and freeing, until we've got 'em all */
1817 	while (count--) {
1818 
1819 		/* Getting interrupted means a leak, but ok at disconnect */
1820 		ret = down_interruptible(&dlfb->urbs.limit_sem);
1821 		if (ret)
1822 			break;
1823 
1824 		spin_lock_irqsave(&dlfb->urbs.lock, flags);
1825 
1826 		node = dlfb->urbs.list.next; /* have reserved one with sem */
1827 		list_del_init(node);
1828 
1829 		spin_unlock_irqrestore(&dlfb->urbs.lock, flags);
1830 
1831 		unode = list_entry(node, struct urb_node, entry);
1832 		urb = unode->urb;
1833 
1834 		/* Free each separately allocated piece */
1835 		usb_free_coherent(urb->dev, dlfb->urbs.size,
1836 				  urb->transfer_buffer, urb->transfer_dma);
1837 		usb_free_urb(urb);
1838 		kfree(node);
1839 	}
1840 
1841 	dlfb->urbs.count = 0;
1842 }
1843 
1844 static int dlfb_alloc_urb_list(struct dlfb_data *dlfb, int count, size_t size)
1845 {
1846 	int i = 0;
1847 	struct urb *urb;
1848 	struct urb_node *unode;
1849 	char *buf;
1850 
1851 	spin_lock_init(&dlfb->urbs.lock);
1852 
1853 	dlfb->urbs.size = size;
1854 	INIT_LIST_HEAD(&dlfb->urbs.list);
1855 
1856 	while (i < count) {
1857 		unode = kzalloc(sizeof(*unode), GFP_KERNEL);
1858 		if (!unode)
1859 			break;
1860 		unode->dlfb = dlfb;
1861 
1862 		INIT_DELAYED_WORK(&unode->release_urb_work,
1863 			  dlfb_release_urb_work);
1864 
1865 		urb = usb_alloc_urb(0, GFP_KERNEL);
1866 		if (!urb) {
1867 			kfree(unode);
1868 			break;
1869 		}
1870 		unode->urb = urb;
1871 
1872 		buf = usb_alloc_coherent(dlfb->udev, MAX_TRANSFER, GFP_KERNEL,
1873 					 &urb->transfer_dma);
1874 		if (!buf) {
1875 			kfree(unode);
1876 			usb_free_urb(urb);
1877 			break;
1878 		}
1879 
1880 		/* urb->transfer_buffer_length set to actual before submit */
1881 		usb_fill_bulk_urb(urb, dlfb->udev, usb_sndbulkpipe(dlfb->udev, 1),
1882 			buf, size, dlfb_urb_completion, unode);
1883 		urb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;
1884 
1885 		list_add_tail(&unode->entry, &dlfb->urbs.list);
1886 
1887 		i++;
1888 	}
1889 
1890 	sema_init(&dlfb->urbs.limit_sem, i);
1891 	dlfb->urbs.count = i;
1892 	dlfb->urbs.available = i;
1893 
1894 	return i;
1895 }
1896 
1897 static struct urb *dlfb_get_urb(struct dlfb_data *dlfb)
1898 {
1899 	int ret;
1900 	struct list_head *entry;
1901 	struct urb_node *unode;
1902 	unsigned long flags;
1903 
1904 	/* Wait for an in-flight buffer to complete and get re-queued */
1905 	ret = down_timeout(&dlfb->urbs.limit_sem, GET_URB_TIMEOUT);
1906 	if (ret) {
1907 		atomic_set(&dlfb->lost_pixels, 1);
1908 		dev_warn(&dlfb->udev->dev,
1909 			 "wait for urb interrupted: %d available: %d\n",
1910 			 ret, dlfb->urbs.available);
1911 		return NULL;
1912 	}
1913 
1914 	spin_lock_irqsave(&dlfb->urbs.lock, flags);
1915 
1916 	BUG_ON(list_empty(&dlfb->urbs.list)); /* reserved one with limit_sem */
1917 	entry = dlfb->urbs.list.next;
1918 	list_del_init(entry);
1919 	dlfb->urbs.available--;
1920 
1921 	spin_unlock_irqrestore(&dlfb->urbs.lock, flags);
1922 
1923 	unode = list_entry(entry, struct urb_node, entry);
1924 	return unode->urb;
1925 }
1926 
1927 static int dlfb_submit_urb(struct dlfb_data *dlfb, struct urb *urb, size_t len)
1928 {
1929 	int ret;
1930 
1931 	BUG_ON(len > dlfb->urbs.size);
1932 
1933 	urb->transfer_buffer_length = len; /* set to actual payload len */
1934 	ret = usb_submit_urb(urb, GFP_KERNEL);
1935 	if (ret) {
1936 		dlfb_urb_completion(urb); /* because no one else will */
1937 		atomic_set(&dlfb->lost_pixels, 1);
1938 		dev_err(&dlfb->udev->dev, "submit urb error: %d\n", ret);
1939 	}
1940 	return ret;
1941 }
1942 
1943 module_param(console, bool, S_IWUSR | S_IRUSR | S_IWGRP | S_IRGRP);
1944 MODULE_PARM_DESC(console, "Allow fbcon to open framebuffer");
1945 
1946 module_param(fb_defio, bool, S_IWUSR | S_IRUSR | S_IWGRP | S_IRGRP);
1947 MODULE_PARM_DESC(fb_defio, "Page fault detection of mmap writes");
1948 
1949 module_param(shadow, bool, S_IWUSR | S_IRUSR | S_IWGRP | S_IRGRP);
1950 MODULE_PARM_DESC(shadow, "Shadow vid mem. Disable to save mem but lose perf");
1951 
1952 module_param(pixel_limit, int, S_IWUSR | S_IRUSR | S_IWGRP | S_IRGRP);
1953 MODULE_PARM_DESC(pixel_limit, "Force limit on max mode (in x*y pixels)");
1954 
1955 MODULE_AUTHOR("Roberto De Ioris <roberto@unbit.it>, "
1956 	      "Jaya Kumar <jayakumar.lkml@gmail.com>, "
1957 	      "Bernie Thompson <bernie@plugable.com>");
1958 MODULE_DESCRIPTION("DisplayLink kernel framebuffer driver");
1959 MODULE_LICENSE("GPL");
1960 
1961