xref: /openbmc/linux/drivers/video/fbdev/udlfb.c (revision 0da7e432)
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 
432 	while ((pixel_end > pixel) &&
433 	       (cmd_buffer_end - MIN_RLX_CMD_BYTES > cmd)) {
434 		uint8_t *raw_pixels_count_byte = NULL;
435 		uint8_t *cmd_pixels_count_byte = NULL;
436 		const uint16_t *raw_pixel_start = NULL;
437 		const uint16_t *cmd_pixel_start, *cmd_pixel_end = NULL;
438 
439 		prefetchw((void *) cmd); /* pull in one cache line at least */
440 
441 		*cmd++ = 0xAF;
442 		*cmd++ = 0x6B;
443 		*cmd++ = dev_addr >> 16;
444 		*cmd++ = dev_addr >> 8;
445 		*cmd++ = dev_addr;
446 
447 		cmd_pixels_count_byte = cmd++; /*  we'll know this later */
448 		cmd_pixel_start = pixel;
449 
450 		raw_pixels_count_byte = cmd++; /*  we'll know this later */
451 		raw_pixel_start = pixel;
452 
453 		cmd_pixel_end = pixel + min(MAX_CMD_PIXELS + 1,
454 			min((int)(pixel_end - pixel),
455 			    (int)(cmd_buffer_end - cmd) / BPP));
456 
457 		prefetch_range((void *) pixel, (cmd_pixel_end - pixel) * BPP);
458 
459 		while (pixel < cmd_pixel_end) {
460 			const uint16_t * const repeating_pixel = pixel;
461 
462 			*cmd++ = *pixel >> 8;
463 			*cmd++ = *pixel;
464 			pixel++;
465 
466 			if (unlikely((pixel < cmd_pixel_end) &&
467 				     (*pixel == *repeating_pixel))) {
468 				/* go back and fill in raw pixel count */
469 				*raw_pixels_count_byte = ((repeating_pixel -
470 						raw_pixel_start) + 1) & 0xFF;
471 
472 				while ((pixel < cmd_pixel_end)
473 				       && (*pixel == *repeating_pixel)) {
474 					pixel++;
475 				}
476 
477 				/* immediately after raw data is repeat byte */
478 				*cmd++ = ((pixel - repeating_pixel) - 1) & 0xFF;
479 
480 				/* Then start another raw pixel span */
481 				raw_pixel_start = pixel;
482 				raw_pixels_count_byte = cmd++;
483 			}
484 		}
485 
486 		if (pixel > raw_pixel_start) {
487 			/* finalize last RAW span */
488 			*raw_pixels_count_byte = (pixel-raw_pixel_start) & 0xFF;
489 		}
490 
491 		*cmd_pixels_count_byte = (pixel - cmd_pixel_start) & 0xFF;
492 		dev_addr += (pixel - cmd_pixel_start) * BPP;
493 	}
494 
495 	if (cmd_buffer_end <= MIN_RLX_CMD_BYTES + cmd) {
496 		/* Fill leftover bytes with no-ops */
497 		if (cmd_buffer_end > cmd)
498 			memset(cmd, 0xAF, cmd_buffer_end - cmd);
499 		cmd = (uint8_t *) cmd_buffer_end;
500 	}
501 
502 	*command_buffer_ptr = cmd;
503 	*pixel_start_ptr = pixel;
504 	*device_address_ptr = dev_addr;
505 }
506 
507 /*
508  * There are 3 copies of every pixel: The front buffer that the fbdev
509  * client renders to, the actual framebuffer across the USB bus in hardware
510  * (that we can only write to, slowly, and can never read), and (optionally)
511  * our shadow copy that tracks what's been sent to that hardware buffer.
512  */
513 static int dlfb_render_hline(struct dlfb_data *dlfb, struct urb **urb_ptr,
514 			      const char *front, char **urb_buf_ptr,
515 			      u32 byte_offset, u32 byte_width,
516 			      int *ident_ptr, int *sent_ptr)
517 {
518 	const u8 *line_start, *line_end, *next_pixel;
519 	u32 dev_addr = dlfb->base16 + byte_offset;
520 	struct urb *urb = *urb_ptr;
521 	u8 *cmd = *urb_buf_ptr;
522 	u8 *cmd_end = (u8 *) urb->transfer_buffer + urb->transfer_buffer_length;
523 
524 	line_start = (u8 *) (front + byte_offset);
525 	next_pixel = line_start;
526 	line_end = next_pixel + byte_width;
527 
528 	if (dlfb->backing_buffer) {
529 		int offset;
530 		const u8 *back_start = (u8 *) (dlfb->backing_buffer
531 						+ byte_offset);
532 
533 		*ident_ptr += dlfb_trim_hline(back_start, &next_pixel,
534 			&byte_width);
535 
536 		offset = next_pixel - line_start;
537 		line_end = next_pixel + byte_width;
538 		dev_addr += offset;
539 		back_start += offset;
540 		line_start += offset;
541 
542 		memcpy((char *)back_start, (char *) line_start,
543 		       byte_width);
544 	}
545 
546 	while (next_pixel < line_end) {
547 
548 		dlfb_compress_hline((const uint16_t **) &next_pixel,
549 			     (const uint16_t *) line_end, &dev_addr,
550 			(u8 **) &cmd, (u8 *) cmd_end);
551 
552 		if (cmd >= cmd_end) {
553 			int len = cmd - (u8 *) urb->transfer_buffer;
554 			if (dlfb_submit_urb(dlfb, urb, len))
555 				return 1; /* lost pixels is set */
556 			*sent_ptr += len;
557 			urb = dlfb_get_urb(dlfb);
558 			if (!urb)
559 				return 1; /* lost_pixels is set */
560 			*urb_ptr = urb;
561 			cmd = urb->transfer_buffer;
562 			cmd_end = &cmd[urb->transfer_buffer_length];
563 		}
564 	}
565 
566 	*urb_buf_ptr = cmd;
567 
568 	return 0;
569 }
570 
571 static int dlfb_handle_damage(struct dlfb_data *dlfb, int x, int y,
572 	       int width, int height, char *data)
573 {
574 	int i, ret;
575 	char *cmd;
576 	cycles_t start_cycles, end_cycles;
577 	int bytes_sent = 0;
578 	int bytes_identical = 0;
579 	struct urb *urb;
580 	int aligned_x;
581 
582 	start_cycles = get_cycles();
583 
584 	aligned_x = DL_ALIGN_DOWN(x, sizeof(unsigned long));
585 	width = DL_ALIGN_UP(width + (x-aligned_x), sizeof(unsigned long));
586 	x = aligned_x;
587 
588 	if ((width <= 0) ||
589 	    (x + width > dlfb->info->var.xres) ||
590 	    (y + height > dlfb->info->var.yres))
591 		return -EINVAL;
592 
593 	if (!atomic_read(&dlfb->usb_active))
594 		return 0;
595 
596 	urb = dlfb_get_urb(dlfb);
597 	if (!urb)
598 		return 0;
599 	cmd = urb->transfer_buffer;
600 
601 	for (i = y; i < y + height ; i++) {
602 		const int line_offset = dlfb->info->fix.line_length * i;
603 		const int byte_offset = line_offset + (x * BPP);
604 
605 		if (dlfb_render_hline(dlfb, &urb,
606 				      (char *) dlfb->info->fix.smem_start,
607 				      &cmd, byte_offset, width * BPP,
608 				      &bytes_identical, &bytes_sent))
609 			goto error;
610 	}
611 
612 	if (cmd > (char *) urb->transfer_buffer) {
613 		/* Send partial buffer remaining before exiting */
614 		int len = cmd - (char *) urb->transfer_buffer;
615 		ret = dlfb_submit_urb(dlfb, urb, len);
616 		bytes_sent += len;
617 	} else
618 		dlfb_urb_completion(urb);
619 
620 error:
621 	atomic_add(bytes_sent, &dlfb->bytes_sent);
622 	atomic_add(bytes_identical, &dlfb->bytes_identical);
623 	atomic_add(width*height*2, &dlfb->bytes_rendered);
624 	end_cycles = get_cycles();
625 	atomic_add(((unsigned int) ((end_cycles - start_cycles)
626 		    >> 10)), /* Kcycles */
627 		   &dlfb->cpu_kcycles_used);
628 
629 	return 0;
630 }
631 
632 /*
633  * Path triggered by usermode clients who write to filesystem
634  * e.g. cat filename > /dev/fb1
635  * Not used by X Windows or text-mode console. But useful for testing.
636  * Slow because of extra copy and we must assume all pixels dirty.
637  */
638 static ssize_t dlfb_ops_write(struct fb_info *info, const char __user *buf,
639 			  size_t count, loff_t *ppos)
640 {
641 	ssize_t result;
642 	struct dlfb_data *dlfb = info->par;
643 	u32 offset = (u32) *ppos;
644 
645 	result = fb_sys_write(info, buf, count, ppos);
646 
647 	if (result > 0) {
648 		int start = max((int)(offset / info->fix.line_length), 0);
649 		int lines = min((u32)((result / info->fix.line_length) + 1),
650 				(u32)info->var.yres);
651 
652 		dlfb_handle_damage(dlfb, 0, start, info->var.xres,
653 			lines, info->screen_base);
654 	}
655 
656 	return result;
657 }
658 
659 /* hardware has native COPY command (see libdlo), but not worth it for fbcon */
660 static void dlfb_ops_copyarea(struct fb_info *info,
661 				const struct fb_copyarea *area)
662 {
663 
664 	struct dlfb_data *dlfb = info->par;
665 
666 	sys_copyarea(info, area);
667 
668 	dlfb_handle_damage(dlfb, area->dx, area->dy,
669 			area->width, area->height, info->screen_base);
670 }
671 
672 static void dlfb_ops_imageblit(struct fb_info *info,
673 				const struct fb_image *image)
674 {
675 	struct dlfb_data *dlfb = info->par;
676 
677 	sys_imageblit(info, image);
678 
679 	dlfb_handle_damage(dlfb, image->dx, image->dy,
680 			image->width, image->height, info->screen_base);
681 }
682 
683 static void dlfb_ops_fillrect(struct fb_info *info,
684 			  const struct fb_fillrect *rect)
685 {
686 	struct dlfb_data *dlfb = info->par;
687 
688 	sys_fillrect(info, rect);
689 
690 	dlfb_handle_damage(dlfb, rect->dx, rect->dy, rect->width,
691 			      rect->height, info->screen_base);
692 }
693 
694 /*
695  * NOTE: fb_defio.c is holding info->fbdefio.mutex
696  *   Touching ANY framebuffer memory that triggers a page fault
697  *   in fb_defio will cause a deadlock, when it also tries to
698  *   grab the same mutex.
699  */
700 static void dlfb_dpy_deferred_io(struct fb_info *info,
701 				struct list_head *pagelist)
702 {
703 	struct page *cur;
704 	struct fb_deferred_io *fbdefio = info->fbdefio;
705 	struct dlfb_data *dlfb = info->par;
706 	struct urb *urb;
707 	char *cmd;
708 	cycles_t start_cycles, end_cycles;
709 	int bytes_sent = 0;
710 	int bytes_identical = 0;
711 	int bytes_rendered = 0;
712 
713 	if (!fb_defio)
714 		return;
715 
716 	if (!atomic_read(&dlfb->usb_active))
717 		return;
718 
719 	start_cycles = get_cycles();
720 
721 	urb = dlfb_get_urb(dlfb);
722 	if (!urb)
723 		return;
724 
725 	cmd = urb->transfer_buffer;
726 
727 	/* walk the written page list and render each to device */
728 	list_for_each_entry(cur, &fbdefio->pagelist, lru) {
729 
730 		if (dlfb_render_hline(dlfb, &urb, (char *) info->fix.smem_start,
731 				  &cmd, cur->index << PAGE_SHIFT,
732 				  PAGE_SIZE, &bytes_identical, &bytes_sent))
733 			goto error;
734 		bytes_rendered += PAGE_SIZE;
735 	}
736 
737 	if (cmd > (char *) urb->transfer_buffer) {
738 		/* Send partial buffer remaining before exiting */
739 		int len = cmd - (char *) urb->transfer_buffer;
740 		dlfb_submit_urb(dlfb, urb, len);
741 		bytes_sent += len;
742 	} else
743 		dlfb_urb_completion(urb);
744 
745 error:
746 	atomic_add(bytes_sent, &dlfb->bytes_sent);
747 	atomic_add(bytes_identical, &dlfb->bytes_identical);
748 	atomic_add(bytes_rendered, &dlfb->bytes_rendered);
749 	end_cycles = get_cycles();
750 	atomic_add(((unsigned int) ((end_cycles - start_cycles)
751 		    >> 10)), /* Kcycles */
752 		   &dlfb->cpu_kcycles_used);
753 }
754 
755 static int dlfb_get_edid(struct dlfb_data *dlfb, char *edid, int len)
756 {
757 	int i, ret;
758 	char *rbuf;
759 
760 	rbuf = kmalloc(2, GFP_KERNEL);
761 	if (!rbuf)
762 		return 0;
763 
764 	for (i = 0; i < len; i++) {
765 		ret = usb_control_msg(dlfb->udev,
766 				      usb_rcvctrlpipe(dlfb->udev, 0), 0x02,
767 				      (0x80 | (0x02 << 5)), i << 8, 0xA1,
768 				      rbuf, 2, USB_CTRL_GET_TIMEOUT);
769 		if (ret < 2) {
770 			dev_err(&dlfb->udev->dev,
771 				"Read EDID byte %d failed: %d\n", i, ret);
772 			i--;
773 			break;
774 		}
775 		edid[i] = rbuf[1];
776 	}
777 
778 	kfree(rbuf);
779 
780 	return i;
781 }
782 
783 static int dlfb_ops_ioctl(struct fb_info *info, unsigned int cmd,
784 				unsigned long arg)
785 {
786 
787 	struct dlfb_data *dlfb = info->par;
788 
789 	if (!atomic_read(&dlfb->usb_active))
790 		return 0;
791 
792 	/* TODO: Update X server to get this from sysfs instead */
793 	if (cmd == DLFB_IOCTL_RETURN_EDID) {
794 		void __user *edid = (void __user *)arg;
795 		if (copy_to_user(edid, dlfb->edid, dlfb->edid_size))
796 			return -EFAULT;
797 		return 0;
798 	}
799 
800 	/* TODO: Help propose a standard fb.h ioctl to report mmap damage */
801 	if (cmd == DLFB_IOCTL_REPORT_DAMAGE) {
802 		struct dloarea area;
803 
804 		if (copy_from_user(&area, (void __user *)arg,
805 				  sizeof(struct dloarea)))
806 			return -EFAULT;
807 
808 		/*
809 		 * If we have a damage-aware client, turn fb_defio "off"
810 		 * To avoid perf imact of unnecessary page fault handling.
811 		 * Done by resetting the delay for this fb_info to a very
812 		 * long period. Pages will become writable and stay that way.
813 		 * Reset to normal value when all clients have closed this fb.
814 		 */
815 		if (info->fbdefio)
816 			info->fbdefio->delay = DL_DEFIO_WRITE_DISABLE;
817 
818 		if (area.x < 0)
819 			area.x = 0;
820 
821 		if (area.x > info->var.xres)
822 			area.x = info->var.xres;
823 
824 		if (area.y < 0)
825 			area.y = 0;
826 
827 		if (area.y > info->var.yres)
828 			area.y = info->var.yres;
829 
830 		dlfb_handle_damage(dlfb, area.x, area.y, area.w, area.h,
831 			   info->screen_base);
832 	}
833 
834 	return 0;
835 }
836 
837 /* taken from vesafb */
838 static int
839 dlfb_ops_setcolreg(unsigned regno, unsigned red, unsigned green,
840 	       unsigned blue, unsigned transp, struct fb_info *info)
841 {
842 	int err = 0;
843 
844 	if (regno >= info->cmap.len)
845 		return 1;
846 
847 	if (regno < 16) {
848 		if (info->var.red.offset == 10) {
849 			/* 1:5:5:5 */
850 			((u32 *) (info->pseudo_palette))[regno] =
851 			    ((red & 0xf800) >> 1) |
852 			    ((green & 0xf800) >> 6) | ((blue & 0xf800) >> 11);
853 		} else {
854 			/* 0:5:6:5 */
855 			((u32 *) (info->pseudo_palette))[regno] =
856 			    ((red & 0xf800)) |
857 			    ((green & 0xfc00) >> 5) | ((blue & 0xf800) >> 11);
858 		}
859 	}
860 
861 	return err;
862 }
863 
864 /*
865  * It's common for several clients to have framebuffer open simultaneously.
866  * e.g. both fbcon and X. Makes things interesting.
867  * Assumes caller is holding info->lock (for open and release at least)
868  */
869 static int dlfb_ops_open(struct fb_info *info, int user)
870 {
871 	struct dlfb_data *dlfb = info->par;
872 
873 	/*
874 	 * fbcon aggressively connects to first framebuffer it finds,
875 	 * preventing other clients (X) from working properly. Usually
876 	 * not what the user wants. Fail by default with option to enable.
877 	 */
878 	if ((user == 0) && (!console))
879 		return -EBUSY;
880 
881 	/* If the USB device is gone, we don't accept new opens */
882 	if (dlfb->virtualized)
883 		return -ENODEV;
884 
885 	dlfb->fb_count++;
886 
887 	kref_get(&dlfb->kref);
888 
889 	if (fb_defio && (info->fbdefio == NULL)) {
890 		/* enable defio at last moment if not disabled by client */
891 
892 		struct fb_deferred_io *fbdefio;
893 
894 		fbdefio = kzalloc(sizeof(struct fb_deferred_io), GFP_KERNEL);
895 
896 		if (fbdefio) {
897 			fbdefio->delay = DL_DEFIO_WRITE_DELAY;
898 			fbdefio->deferred_io = dlfb_dpy_deferred_io;
899 		}
900 
901 		info->fbdefio = fbdefio;
902 		fb_deferred_io_init(info);
903 	}
904 
905 	dev_dbg(info->dev, "open, user=%d fb_info=%p count=%d\n",
906 		user, info, dlfb->fb_count);
907 
908 	return 0;
909 }
910 
911 /*
912  * Called when all client interfaces to start transactions have been disabled,
913  * and all references to our device instance (dlfb_data) are released.
914  * Every transaction must have a reference, so we know are fully spun down
915  */
916 static void dlfb_free(struct kref *kref)
917 {
918 	struct dlfb_data *dlfb = container_of(kref, struct dlfb_data, kref);
919 
920 	vfree(dlfb->backing_buffer);
921 	kfree(dlfb->edid);
922 	kfree(dlfb);
923 }
924 
925 static void dlfb_release_urb_work(struct work_struct *work)
926 {
927 	struct urb_node *unode = container_of(work, struct urb_node,
928 					      release_urb_work.work);
929 
930 	up(&unode->dlfb->urbs.limit_sem);
931 }
932 
933 static void dlfb_free_framebuffer(struct dlfb_data *dlfb)
934 {
935 	struct fb_info *info = dlfb->info;
936 
937 	if (info) {
938 		unregister_framebuffer(info);
939 
940 		if (info->cmap.len != 0)
941 			fb_dealloc_cmap(&info->cmap);
942 		if (info->monspecs.modedb)
943 			fb_destroy_modedb(info->monspecs.modedb);
944 		vfree(info->screen_base);
945 
946 		fb_destroy_modelist(&info->modelist);
947 
948 		dlfb->info = NULL;
949 
950 		/* Assume info structure is freed after this point */
951 		framebuffer_release(info);
952 	}
953 
954 	/* ref taken in probe() as part of registering framebfufer */
955 	kref_put(&dlfb->kref, dlfb_free);
956 }
957 
958 static void dlfb_free_framebuffer_work(struct work_struct *work)
959 {
960 	struct dlfb_data *dlfb = container_of(work, struct dlfb_data,
961 					     free_framebuffer_work.work);
962 	dlfb_free_framebuffer(dlfb);
963 }
964 /*
965  * Assumes caller is holding info->lock mutex (for open and release at least)
966  */
967 static int dlfb_ops_release(struct fb_info *info, int user)
968 {
969 	struct dlfb_data *dlfb = info->par;
970 
971 	dlfb->fb_count--;
972 
973 	/* We can't free fb_info here - fbmem will touch it when we return */
974 	if (dlfb->virtualized && (dlfb->fb_count == 0))
975 		schedule_delayed_work(&dlfb->free_framebuffer_work, HZ);
976 
977 	if ((dlfb->fb_count == 0) && (info->fbdefio)) {
978 		fb_deferred_io_cleanup(info);
979 		kfree(info->fbdefio);
980 		info->fbdefio = NULL;
981 		info->fbops->fb_mmap = dlfb_ops_mmap;
982 	}
983 
984 	dev_dbg(info->dev, "release, user=%d count=%d\n", user, dlfb->fb_count);
985 
986 	kref_put(&dlfb->kref, dlfb_free);
987 
988 	return 0;
989 }
990 
991 /*
992  * Check whether a video mode is supported by the DisplayLink chip
993  * We start from monitor's modes, so don't need to filter that here
994  */
995 static int dlfb_is_valid_mode(struct fb_videomode *mode, struct dlfb_data *dlfb)
996 {
997 	if (mode->xres * mode->yres > dlfb->sku_pixel_limit)
998 		return 0;
999 
1000 	return 1;
1001 }
1002 
1003 static void dlfb_var_color_format(struct fb_var_screeninfo *var)
1004 {
1005 	const struct fb_bitfield red = { 11, 5, 0 };
1006 	const struct fb_bitfield green = { 5, 6, 0 };
1007 	const struct fb_bitfield blue = { 0, 5, 0 };
1008 
1009 	var->bits_per_pixel = 16;
1010 	var->red = red;
1011 	var->green = green;
1012 	var->blue = blue;
1013 }
1014 
1015 static int dlfb_ops_check_var(struct fb_var_screeninfo *var,
1016 				struct fb_info *info)
1017 {
1018 	struct fb_videomode mode;
1019 	struct dlfb_data *dlfb = info->par;
1020 
1021 	/* TODO: support dynamically changing framebuffer size */
1022 	if ((var->xres * var->yres * 2) > info->fix.smem_len)
1023 		return -EINVAL;
1024 
1025 	/* set device-specific elements of var unrelated to mode */
1026 	dlfb_var_color_format(var);
1027 
1028 	fb_var_to_videomode(&mode, var);
1029 
1030 	if (!dlfb_is_valid_mode(&mode, dlfb))
1031 		return -EINVAL;
1032 
1033 	return 0;
1034 }
1035 
1036 static int dlfb_ops_set_par(struct fb_info *info)
1037 {
1038 	struct dlfb_data *dlfb = info->par;
1039 	int result;
1040 	u16 *pix_framebuffer;
1041 	int i;
1042 
1043 	result = dlfb_set_video_mode(dlfb, &info->var);
1044 
1045 	if ((result == 0) && (dlfb->fb_count == 0)) {
1046 
1047 		/* paint greenscreen */
1048 
1049 		pix_framebuffer = (u16 *) info->screen_base;
1050 		for (i = 0; i < info->fix.smem_len / 2; i++)
1051 			pix_framebuffer[i] = 0x37e6;
1052 
1053 		dlfb_handle_damage(dlfb, 0, 0, info->var.xres, info->var.yres,
1054 				   info->screen_base);
1055 	}
1056 
1057 	return result;
1058 }
1059 
1060 /* To fonzi the jukebox (e.g. make blanking changes take effect) */
1061 static char *dlfb_dummy_render(char *buf)
1062 {
1063 	*buf++ = 0xAF;
1064 	*buf++ = 0x6A; /* copy */
1065 	*buf++ = 0x00; /* from address*/
1066 	*buf++ = 0x00;
1067 	*buf++ = 0x00;
1068 	*buf++ = 0x01; /* one pixel */
1069 	*buf++ = 0x00; /* to address */
1070 	*buf++ = 0x00;
1071 	*buf++ = 0x00;
1072 	return buf;
1073 }
1074 
1075 /*
1076  * In order to come back from full DPMS off, we need to set the mode again
1077  */
1078 static int dlfb_ops_blank(int blank_mode, struct fb_info *info)
1079 {
1080 	struct dlfb_data *dlfb = info->par;
1081 	char *bufptr;
1082 	struct urb *urb;
1083 
1084 	dev_dbg(info->dev, "blank, mode %d --> %d\n",
1085 		dlfb->blank_mode, blank_mode);
1086 
1087 	if ((dlfb->blank_mode == FB_BLANK_POWERDOWN) &&
1088 	    (blank_mode != FB_BLANK_POWERDOWN)) {
1089 
1090 		/* returning from powerdown requires a fresh modeset */
1091 		dlfb_set_video_mode(dlfb, &info->var);
1092 	}
1093 
1094 	urb = dlfb_get_urb(dlfb);
1095 	if (!urb)
1096 		return 0;
1097 
1098 	bufptr = (char *) urb->transfer_buffer;
1099 	bufptr = dlfb_vidreg_lock(bufptr);
1100 	bufptr = dlfb_blanking(bufptr, blank_mode);
1101 	bufptr = dlfb_vidreg_unlock(bufptr);
1102 
1103 	/* seems like a render op is needed to have blank change take effect */
1104 	bufptr = dlfb_dummy_render(bufptr);
1105 
1106 	dlfb_submit_urb(dlfb, urb, bufptr -
1107 			(char *) urb->transfer_buffer);
1108 
1109 	dlfb->blank_mode = blank_mode;
1110 
1111 	return 0;
1112 }
1113 
1114 static struct fb_ops dlfb_ops = {
1115 	.owner = THIS_MODULE,
1116 	.fb_read = fb_sys_read,
1117 	.fb_write = dlfb_ops_write,
1118 	.fb_setcolreg = dlfb_ops_setcolreg,
1119 	.fb_fillrect = dlfb_ops_fillrect,
1120 	.fb_copyarea = dlfb_ops_copyarea,
1121 	.fb_imageblit = dlfb_ops_imageblit,
1122 	.fb_mmap = dlfb_ops_mmap,
1123 	.fb_ioctl = dlfb_ops_ioctl,
1124 	.fb_open = dlfb_ops_open,
1125 	.fb_release = dlfb_ops_release,
1126 	.fb_blank = dlfb_ops_blank,
1127 	.fb_check_var = dlfb_ops_check_var,
1128 	.fb_set_par = dlfb_ops_set_par,
1129 };
1130 
1131 
1132 /*
1133  * Assumes &info->lock held by caller
1134  * Assumes no active clients have framebuffer open
1135  */
1136 static int dlfb_realloc_framebuffer(struct dlfb_data *dlfb, struct fb_info *info)
1137 {
1138 	int old_len = info->fix.smem_len;
1139 	int new_len;
1140 	unsigned char *old_fb = info->screen_base;
1141 	unsigned char *new_fb;
1142 	unsigned char *new_back = NULL;
1143 
1144 	new_len = info->fix.line_length * info->var.yres;
1145 
1146 	if (PAGE_ALIGN(new_len) > old_len) {
1147 		/*
1148 		 * Alloc system memory for virtual framebuffer
1149 		 */
1150 		new_fb = vmalloc(new_len);
1151 		if (!new_fb) {
1152 			dev_err(info->dev, "Virtual framebuffer alloc failed\n");
1153 			return -ENOMEM;
1154 		}
1155 
1156 		if (info->screen_base) {
1157 			memcpy(new_fb, old_fb, old_len);
1158 			vfree(info->screen_base);
1159 		}
1160 
1161 		info->screen_base = new_fb;
1162 		info->fix.smem_len = PAGE_ALIGN(new_len);
1163 		info->fix.smem_start = (unsigned long) new_fb;
1164 		info->flags = udlfb_info_flags;
1165 
1166 		/*
1167 		 * Second framebuffer copy to mirror the framebuffer state
1168 		 * on the physical USB device. We can function without this.
1169 		 * But with imperfect damage info we may send pixels over USB
1170 		 * that were, in fact, unchanged - wasting limited USB bandwidth
1171 		 */
1172 		if (shadow)
1173 			new_back = vzalloc(new_len);
1174 		if (!new_back)
1175 			dev_info(info->dev,
1176 				 "No shadow/backing buffer allocated\n");
1177 		else {
1178 			vfree(dlfb->backing_buffer);
1179 			dlfb->backing_buffer = new_back;
1180 		}
1181 	}
1182 	return 0;
1183 }
1184 
1185 /*
1186  * 1) Get EDID from hw, or use sw default
1187  * 2) Parse into various fb_info structs
1188  * 3) Allocate virtual framebuffer memory to back highest res mode
1189  *
1190  * Parses EDID into three places used by various parts of fbdev:
1191  * fb_var_screeninfo contains the timing of the monitor's preferred mode
1192  * fb_info.monspecs is full parsed EDID info, including monspecs.modedb
1193  * fb_info.modelist is a linked list of all monitor & VESA modes which work
1194  *
1195  * If EDID is not readable/valid, then modelist is all VESA modes,
1196  * monspecs is NULL, and fb_var_screeninfo is set to safe VESA mode
1197  * Returns 0 if successful
1198  */
1199 static int dlfb_setup_modes(struct dlfb_data *dlfb,
1200 			   struct fb_info *info,
1201 			   char *default_edid, size_t default_edid_size)
1202 {
1203 	char *edid;
1204 	int i, result = 0, tries = 3;
1205 	struct device *dev = info->device;
1206 	struct fb_videomode *mode;
1207 	const struct fb_videomode *default_vmode = NULL;
1208 
1209 	if (info->dev) {
1210 		/* only use mutex if info has been registered */
1211 		mutex_lock(&info->lock);
1212 		/* parent device is used otherwise */
1213 		dev = info->dev;
1214 	}
1215 
1216 	edid = kmalloc(EDID_LENGTH, GFP_KERNEL);
1217 	if (!edid) {
1218 		result = -ENOMEM;
1219 		goto error;
1220 	}
1221 
1222 	fb_destroy_modelist(&info->modelist);
1223 	memset(&info->monspecs, 0, sizeof(info->monspecs));
1224 
1225 	/*
1226 	 * Try to (re)read EDID from hardware first
1227 	 * EDID data may return, but not parse as valid
1228 	 * Try again a few times, in case of e.g. analog cable noise
1229 	 */
1230 	while (tries--) {
1231 
1232 		i = dlfb_get_edid(dlfb, edid, EDID_LENGTH);
1233 
1234 		if (i >= EDID_LENGTH)
1235 			fb_edid_to_monspecs(edid, &info->monspecs);
1236 
1237 		if (info->monspecs.modedb_len > 0) {
1238 			dlfb->edid = edid;
1239 			dlfb->edid_size = i;
1240 			break;
1241 		}
1242 	}
1243 
1244 	/* If that fails, use a previously returned EDID if available */
1245 	if (info->monspecs.modedb_len == 0) {
1246 		dev_err(dev, "Unable to get valid EDID from device/display\n");
1247 
1248 		if (dlfb->edid) {
1249 			fb_edid_to_monspecs(dlfb->edid, &info->monspecs);
1250 			if (info->monspecs.modedb_len > 0)
1251 				dev_err(dev, "Using previously queried EDID\n");
1252 		}
1253 	}
1254 
1255 	/* If that fails, use the default EDID we were handed */
1256 	if (info->monspecs.modedb_len == 0) {
1257 		if (default_edid_size >= EDID_LENGTH) {
1258 			fb_edid_to_monspecs(default_edid, &info->monspecs);
1259 			if (info->monspecs.modedb_len > 0) {
1260 				memcpy(edid, default_edid, default_edid_size);
1261 				dlfb->edid = edid;
1262 				dlfb->edid_size = default_edid_size;
1263 				dev_err(dev, "Using default/backup EDID\n");
1264 			}
1265 		}
1266 	}
1267 
1268 	/* If we've got modes, let's pick a best default mode */
1269 	if (info->monspecs.modedb_len > 0) {
1270 
1271 		for (i = 0; i < info->monspecs.modedb_len; i++) {
1272 			mode = &info->monspecs.modedb[i];
1273 			if (dlfb_is_valid_mode(mode, dlfb)) {
1274 				fb_add_videomode(mode, &info->modelist);
1275 			} else {
1276 				dev_dbg(dev, "Specified mode %dx%d too big\n",
1277 					mode->xres, mode->yres);
1278 				if (i == 0)
1279 					/* if we've removed top/best mode */
1280 					info->monspecs.misc
1281 						&= ~FB_MISC_1ST_DETAIL;
1282 			}
1283 		}
1284 
1285 		default_vmode = fb_find_best_display(&info->monspecs,
1286 						     &info->modelist);
1287 	}
1288 
1289 	/* If everything else has failed, fall back to safe default mode */
1290 	if (default_vmode == NULL) {
1291 
1292 		struct fb_videomode fb_vmode = {0};
1293 
1294 		/*
1295 		 * Add the standard VESA modes to our modelist
1296 		 * Since we don't have EDID, there may be modes that
1297 		 * overspec monitor and/or are incorrect aspect ratio, etc.
1298 		 * But at least the user has a chance to choose
1299 		 */
1300 		for (i = 0; i < VESA_MODEDB_SIZE; i++) {
1301 			mode = (struct fb_videomode *)&vesa_modes[i];
1302 			if (dlfb_is_valid_mode(mode, dlfb))
1303 				fb_add_videomode(mode, &info->modelist);
1304 			else
1305 				dev_dbg(dev, "VESA mode %dx%d too big\n",
1306 					mode->xres, mode->yres);
1307 		}
1308 
1309 		/*
1310 		 * default to resolution safe for projectors
1311 		 * (since they are most common case without EDID)
1312 		 */
1313 		fb_vmode.xres = 800;
1314 		fb_vmode.yres = 600;
1315 		fb_vmode.refresh = 60;
1316 		default_vmode = fb_find_nearest_mode(&fb_vmode,
1317 						     &info->modelist);
1318 	}
1319 
1320 	/* If we have good mode and no active clients*/
1321 	if ((default_vmode != NULL) && (dlfb->fb_count == 0)) {
1322 
1323 		fb_videomode_to_var(&info->var, default_vmode);
1324 		dlfb_var_color_format(&info->var);
1325 
1326 		/*
1327 		 * with mode size info, we can now alloc our framebuffer.
1328 		 */
1329 		memcpy(&info->fix, &dlfb_fix, sizeof(dlfb_fix));
1330 		info->fix.line_length = info->var.xres *
1331 			(info->var.bits_per_pixel / 8);
1332 
1333 		result = dlfb_realloc_framebuffer(dlfb, info);
1334 
1335 	} else
1336 		result = -EINVAL;
1337 
1338 error:
1339 	if (edid && (dlfb->edid != edid))
1340 		kfree(edid);
1341 
1342 	if (info->dev)
1343 		mutex_unlock(&info->lock);
1344 
1345 	return result;
1346 }
1347 
1348 static ssize_t metrics_bytes_rendered_show(struct device *fbdev,
1349 				   struct device_attribute *a, char *buf) {
1350 	struct fb_info *fb_info = dev_get_drvdata(fbdev);
1351 	struct dlfb_data *dlfb = fb_info->par;
1352 	return snprintf(buf, PAGE_SIZE, "%u\n",
1353 			atomic_read(&dlfb->bytes_rendered));
1354 }
1355 
1356 static ssize_t metrics_bytes_identical_show(struct device *fbdev,
1357 				   struct device_attribute *a, char *buf) {
1358 	struct fb_info *fb_info = dev_get_drvdata(fbdev);
1359 	struct dlfb_data *dlfb = fb_info->par;
1360 	return snprintf(buf, PAGE_SIZE, "%u\n",
1361 			atomic_read(&dlfb->bytes_identical));
1362 }
1363 
1364 static ssize_t metrics_bytes_sent_show(struct device *fbdev,
1365 				   struct device_attribute *a, char *buf) {
1366 	struct fb_info *fb_info = dev_get_drvdata(fbdev);
1367 	struct dlfb_data *dlfb = fb_info->par;
1368 	return snprintf(buf, PAGE_SIZE, "%u\n",
1369 			atomic_read(&dlfb->bytes_sent));
1370 }
1371 
1372 static ssize_t metrics_cpu_kcycles_used_show(struct device *fbdev,
1373 				   struct device_attribute *a, char *buf) {
1374 	struct fb_info *fb_info = dev_get_drvdata(fbdev);
1375 	struct dlfb_data *dlfb = fb_info->par;
1376 	return snprintf(buf, PAGE_SIZE, "%u\n",
1377 			atomic_read(&dlfb->cpu_kcycles_used));
1378 }
1379 
1380 static ssize_t edid_show(
1381 			struct file *filp,
1382 			struct kobject *kobj, struct bin_attribute *a,
1383 			 char *buf, loff_t off, size_t count) {
1384 	struct device *fbdev = container_of(kobj, struct device, kobj);
1385 	struct fb_info *fb_info = dev_get_drvdata(fbdev);
1386 	struct dlfb_data *dlfb = fb_info->par;
1387 
1388 	if (dlfb->edid == NULL)
1389 		return 0;
1390 
1391 	if ((off >= dlfb->edid_size) || (count > dlfb->edid_size))
1392 		return 0;
1393 
1394 	if (off + count > dlfb->edid_size)
1395 		count = dlfb->edid_size - off;
1396 
1397 	memcpy(buf, dlfb->edid, count);
1398 
1399 	return count;
1400 }
1401 
1402 static ssize_t edid_store(
1403 			struct file *filp,
1404 			struct kobject *kobj, struct bin_attribute *a,
1405 			char *src, loff_t src_off, size_t src_size) {
1406 	struct device *fbdev = container_of(kobj, struct device, kobj);
1407 	struct fb_info *fb_info = dev_get_drvdata(fbdev);
1408 	struct dlfb_data *dlfb = fb_info->par;
1409 	int ret;
1410 
1411 	/* We only support write of entire EDID at once, no offset*/
1412 	if ((src_size != EDID_LENGTH) || (src_off != 0))
1413 		return -EINVAL;
1414 
1415 	ret = dlfb_setup_modes(dlfb, fb_info, src, src_size);
1416 	if (ret)
1417 		return ret;
1418 
1419 	if (!dlfb->edid || memcmp(src, dlfb->edid, src_size))
1420 		return -EINVAL;
1421 
1422 	dlfb_ops_set_par(fb_info);
1423 	return src_size;
1424 }
1425 
1426 static ssize_t metrics_reset_store(struct device *fbdev,
1427 			   struct device_attribute *attr,
1428 			   const char *buf, size_t count)
1429 {
1430 	struct fb_info *fb_info = dev_get_drvdata(fbdev);
1431 	struct dlfb_data *dlfb = fb_info->par;
1432 
1433 	atomic_set(&dlfb->bytes_rendered, 0);
1434 	atomic_set(&dlfb->bytes_identical, 0);
1435 	atomic_set(&dlfb->bytes_sent, 0);
1436 	atomic_set(&dlfb->cpu_kcycles_used, 0);
1437 
1438 	return count;
1439 }
1440 
1441 static const struct bin_attribute edid_attr = {
1442 	.attr.name = "edid",
1443 	.attr.mode = 0666,
1444 	.size = EDID_LENGTH,
1445 	.read = edid_show,
1446 	.write = edid_store
1447 };
1448 
1449 static const struct device_attribute fb_device_attrs[] = {
1450 	__ATTR_RO(metrics_bytes_rendered),
1451 	__ATTR_RO(metrics_bytes_identical),
1452 	__ATTR_RO(metrics_bytes_sent),
1453 	__ATTR_RO(metrics_cpu_kcycles_used),
1454 	__ATTR(metrics_reset, S_IWUSR, NULL, metrics_reset_store),
1455 };
1456 
1457 /*
1458  * This is necessary before we can communicate with the display controller.
1459  */
1460 static int dlfb_select_std_channel(struct dlfb_data *dlfb)
1461 {
1462 	int ret;
1463 	void *buf;
1464 	static const u8 set_def_chn[] = {
1465 				0x57, 0xCD, 0xDC, 0xA7,
1466 				0x1C, 0x88, 0x5E, 0x15,
1467 				0x60, 0xFE, 0xC6, 0x97,
1468 				0x16, 0x3D, 0x47, 0xF2  };
1469 
1470 	buf = kmemdup(set_def_chn, sizeof(set_def_chn), GFP_KERNEL);
1471 
1472 	if (!buf)
1473 		return -ENOMEM;
1474 
1475 	ret = usb_control_msg(dlfb->udev, usb_sndctrlpipe(dlfb->udev, 0),
1476 			NR_USB_REQUEST_CHANNEL,
1477 			(USB_DIR_OUT | USB_TYPE_VENDOR), 0, 0,
1478 			buf, sizeof(set_def_chn), USB_CTRL_SET_TIMEOUT);
1479 
1480 	kfree(buf);
1481 
1482 	return ret;
1483 }
1484 
1485 static int dlfb_parse_vendor_descriptor(struct dlfb_data *dlfb,
1486 					struct usb_interface *intf)
1487 {
1488 	char *desc;
1489 	char *buf;
1490 	char *desc_end;
1491 	int total_len;
1492 
1493 	buf = kzalloc(MAX_VENDOR_DESCRIPTOR_SIZE, GFP_KERNEL);
1494 	if (!buf)
1495 		return false;
1496 	desc = buf;
1497 
1498 	total_len = usb_get_descriptor(interface_to_usbdev(intf),
1499 					0x5f, /* vendor specific */
1500 					0, desc, MAX_VENDOR_DESCRIPTOR_SIZE);
1501 
1502 	/* if not found, look in configuration descriptor */
1503 	if (total_len < 0) {
1504 		if (0 == usb_get_extra_descriptor(intf->cur_altsetting,
1505 			0x5f, &desc))
1506 			total_len = (int) desc[0];
1507 	}
1508 
1509 	if (total_len > 5) {
1510 		dev_info(&intf->dev,
1511 			 "vendor descriptor length: %d data: %11ph\n",
1512 			 total_len, desc);
1513 
1514 		if ((desc[0] != total_len) || /* descriptor length */
1515 		    (desc[1] != 0x5f) ||   /* vendor descriptor type */
1516 		    (desc[2] != 0x01) ||   /* version (2 bytes) */
1517 		    (desc[3] != 0x00) ||
1518 		    (desc[4] != total_len - 2)) /* length after type */
1519 			goto unrecognized;
1520 
1521 		desc_end = desc + total_len;
1522 		desc += 5; /* the fixed header we've already parsed */
1523 
1524 		while (desc < desc_end) {
1525 			u8 length;
1526 			u16 key;
1527 
1528 			key = *desc++;
1529 			key |= (u16)*desc++ << 8;
1530 			length = *desc++;
1531 
1532 			switch (key) {
1533 			case 0x0200: { /* max_area */
1534 				u32 max_area = *desc++;
1535 				max_area |= (u32)*desc++ << 8;
1536 				max_area |= (u32)*desc++ << 16;
1537 				max_area |= (u32)*desc++ << 24;
1538 				dev_warn(&intf->dev,
1539 					 "DL chip limited to %d pixel modes\n",
1540 					 max_area);
1541 				dlfb->sku_pixel_limit = max_area;
1542 				break;
1543 			}
1544 			default:
1545 				break;
1546 			}
1547 			desc += length;
1548 		}
1549 	} else {
1550 		dev_info(&intf->dev, "vendor descriptor not available (%d)\n",
1551 			 total_len);
1552 	}
1553 
1554 	goto success;
1555 
1556 unrecognized:
1557 	/* allow udlfb to load for now even if firmware unrecognized */
1558 	dev_err(&intf->dev, "Unrecognized vendor firmware descriptor\n");
1559 
1560 success:
1561 	kfree(buf);
1562 	return true;
1563 }
1564 
1565 static void dlfb_init_framebuffer_work(struct work_struct *work);
1566 
1567 static int dlfb_usb_probe(struct usb_interface *intf,
1568 			  const struct usb_device_id *id)
1569 {
1570 	struct dlfb_data *dlfb;
1571 	int retval = -ENOMEM;
1572 	struct usb_device *usbdev = interface_to_usbdev(intf);
1573 
1574 	/* usb initialization */
1575 	dlfb = kzalloc(sizeof(*dlfb), GFP_KERNEL);
1576 	if (!dlfb) {
1577 		dev_err(&intf->dev, "%s: failed to allocate dlfb\n", __func__);
1578 		goto error;
1579 	}
1580 
1581 	kref_init(&dlfb->kref); /* matching kref_put in usb .disconnect fn */
1582 
1583 	dlfb->udev = usbdev;
1584 	usb_set_intfdata(intf, dlfb);
1585 
1586 	dev_dbg(&intf->dev, "console enable=%d\n", console);
1587 	dev_dbg(&intf->dev, "fb_defio enable=%d\n", fb_defio);
1588 	dev_dbg(&intf->dev, "shadow enable=%d\n", shadow);
1589 
1590 	dlfb->sku_pixel_limit = 2048 * 1152; /* default to maximum */
1591 
1592 	if (!dlfb_parse_vendor_descriptor(dlfb, intf)) {
1593 		dev_err(&intf->dev,
1594 			"firmware not recognized, incompatible device?\n");
1595 		goto error;
1596 	}
1597 
1598 	if (pixel_limit) {
1599 		dev_warn(&intf->dev,
1600 			 "DL chip limit of %d overridden to %d\n",
1601 			 dlfb->sku_pixel_limit, pixel_limit);
1602 		dlfb->sku_pixel_limit = pixel_limit;
1603 	}
1604 
1605 
1606 	if (!dlfb_alloc_urb_list(dlfb, WRITES_IN_FLIGHT, MAX_TRANSFER)) {
1607 		retval = -ENOMEM;
1608 		dev_err(&intf->dev, "unable to allocate urb list\n");
1609 		goto error;
1610 	}
1611 
1612 	kref_get(&dlfb->kref); /* matching kref_put in free_framebuffer_work */
1613 
1614 	/* We don't register a new USB class. Our client interface is dlfbev */
1615 
1616 	/* Workitem keep things fast & simple during USB enumeration */
1617 	INIT_DELAYED_WORK(&dlfb->init_framebuffer_work,
1618 			  dlfb_init_framebuffer_work);
1619 	schedule_delayed_work(&dlfb->init_framebuffer_work, 0);
1620 
1621 	return 0;
1622 
1623 error:
1624 	if (dlfb) {
1625 
1626 		kref_put(&dlfb->kref, dlfb_free); /* last ref from kref_init */
1627 
1628 		/* dev has been deallocated. Do not dereference */
1629 	}
1630 
1631 	return retval;
1632 }
1633 
1634 static void dlfb_init_framebuffer_work(struct work_struct *work)
1635 {
1636 	int i, retval;
1637 	struct fb_info *info;
1638 	const struct device_attribute *attr;
1639 	struct dlfb_data *dlfb = container_of(work, struct dlfb_data,
1640 					     init_framebuffer_work.work);
1641 
1642 	/* allocates framebuffer driver structure, not framebuffer memory */
1643 	info = framebuffer_alloc(0, &dlfb->udev->dev);
1644 	if (!info) {
1645 		dev_err(&dlfb->udev->dev, "framebuffer_alloc failed\n");
1646 		goto error;
1647 	}
1648 
1649 	dlfb->info = info;
1650 	info->par = dlfb;
1651 	info->pseudo_palette = dlfb->pseudo_palette;
1652 	info->fbops = &dlfb_ops;
1653 
1654 	retval = fb_alloc_cmap(&info->cmap, 256, 0);
1655 	if (retval < 0) {
1656 		dev_err(info->device, "cmap allocation failed: %d\n", retval);
1657 		goto error;
1658 	}
1659 
1660 	INIT_DELAYED_WORK(&dlfb->free_framebuffer_work,
1661 			  dlfb_free_framebuffer_work);
1662 
1663 	INIT_LIST_HEAD(&info->modelist);
1664 
1665 	retval = dlfb_setup_modes(dlfb, info, NULL, 0);
1666 	if (retval != 0) {
1667 		dev_err(info->device,
1668 			"unable to find common mode for display and adapter\n");
1669 		goto error;
1670 	}
1671 
1672 	/* ready to begin using device */
1673 
1674 	atomic_set(&dlfb->usb_active, 1);
1675 	dlfb_select_std_channel(dlfb);
1676 
1677 	dlfb_ops_check_var(&info->var, info);
1678 	dlfb_ops_set_par(info);
1679 
1680 	retval = register_framebuffer(info);
1681 	if (retval < 0) {
1682 		dev_err(info->device, "unable to register framebuffer: %d\n",
1683 			retval);
1684 		goto error;
1685 	}
1686 
1687 	for (i = 0; i < ARRAY_SIZE(fb_device_attrs); i++) {
1688 		attr = &fb_device_attrs[i];
1689 		retval = device_create_file(info->dev, attr);
1690 		if (retval)
1691 			dev_warn(info->device,
1692 				 "failed to create '%s' attribute: %d\n",
1693 				 attr->attr.name, retval);
1694 	}
1695 
1696 	retval = device_create_bin_file(info->dev, &edid_attr);
1697 	if (retval)
1698 		dev_warn(info->device, "failed to create '%s' attribute: %d\n",
1699 			 edid_attr.attr.name, retval);
1700 
1701 	dev_info(info->device,
1702 		 "%s is DisplayLink USB device (%dx%d, %dK framebuffer memory)\n",
1703 		 dev_name(info->dev), info->var.xres, info->var.yres,
1704 		 ((dlfb->backing_buffer) ?
1705 		 info->fix.smem_len * 2 : info->fix.smem_len) >> 10);
1706 	return;
1707 
1708 error:
1709 	dlfb_free_framebuffer(dlfb);
1710 }
1711 
1712 static void dlfb_usb_disconnect(struct usb_interface *intf)
1713 {
1714 	struct dlfb_data *dlfb;
1715 	struct fb_info *info;
1716 	int i;
1717 
1718 	dlfb = usb_get_intfdata(intf);
1719 	info = dlfb->info;
1720 
1721 	dev_dbg(&intf->dev, "USB disconnect starting\n");
1722 
1723 	/* we virtualize until all fb clients release. Then we free */
1724 	dlfb->virtualized = true;
1725 
1726 	/* When non-active we'll update virtual framebuffer, but no new urbs */
1727 	atomic_set(&dlfb->usb_active, 0);
1728 
1729 	/* this function will wait for all in-flight urbs to complete */
1730 	dlfb_free_urb_list(dlfb);
1731 
1732 	if (info) {
1733 		/* remove udlfb's sysfs interfaces */
1734 		for (i = 0; i < ARRAY_SIZE(fb_device_attrs); i++)
1735 			device_remove_file(info->dev, &fb_device_attrs[i]);
1736 		device_remove_bin_file(info->dev, &edid_attr);
1737 		unlink_framebuffer(info);
1738 	}
1739 
1740 	usb_set_intfdata(intf, NULL);
1741 	dlfb->udev = NULL;
1742 
1743 	/* if clients still have us open, will be freed on last close */
1744 	if (dlfb->fb_count == 0)
1745 		schedule_delayed_work(&dlfb->free_framebuffer_work, 0);
1746 
1747 	/* release reference taken by kref_init in probe() */
1748 	kref_put(&dlfb->kref, dlfb_free);
1749 
1750 	/* consider dlfb_data freed */
1751 }
1752 
1753 static struct usb_driver dlfb_driver = {
1754 	.name = "udlfb",
1755 	.probe = dlfb_usb_probe,
1756 	.disconnect = dlfb_usb_disconnect,
1757 	.id_table = id_table,
1758 };
1759 
1760 module_usb_driver(dlfb_driver);
1761 
1762 static void dlfb_urb_completion(struct urb *urb)
1763 {
1764 	struct urb_node *unode = urb->context;
1765 	struct dlfb_data *dlfb = unode->dlfb;
1766 	unsigned long flags;
1767 
1768 	switch (urb->status) {
1769 	case 0:
1770 		/* success */
1771 		break;
1772 	case -ECONNRESET:
1773 	case -ENOENT:
1774 	case -ESHUTDOWN:
1775 		/* sync/async unlink faults aren't errors */
1776 		break;
1777 	default:
1778 		dev_err(&dlfb->udev->dev,
1779 			"%s - nonzero write bulk status received: %d\n",
1780 			__func__, urb->status);
1781 		atomic_set(&dlfb->lost_pixels, 1);
1782 		break;
1783 	}
1784 
1785 	urb->transfer_buffer_length = dlfb->urbs.size; /* reset to actual */
1786 
1787 	spin_lock_irqsave(&dlfb->urbs.lock, flags);
1788 	list_add_tail(&unode->entry, &dlfb->urbs.list);
1789 	dlfb->urbs.available++;
1790 	spin_unlock_irqrestore(&dlfb->urbs.lock, flags);
1791 
1792 	/*
1793 	 * When using fb_defio, we deadlock if up() is called
1794 	 * while another is waiting. So queue to another process.
1795 	 */
1796 	if (fb_defio)
1797 		schedule_delayed_work(&unode->release_urb_work, 0);
1798 	else
1799 		up(&dlfb->urbs.limit_sem);
1800 }
1801 
1802 static void dlfb_free_urb_list(struct dlfb_data *dlfb)
1803 {
1804 	int count = dlfb->urbs.count;
1805 	struct list_head *node;
1806 	struct urb_node *unode;
1807 	struct urb *urb;
1808 	int ret;
1809 	unsigned long flags;
1810 
1811 	/* keep waiting and freeing, until we've got 'em all */
1812 	while (count--) {
1813 
1814 		/* Getting interrupted means a leak, but ok at disconnect */
1815 		ret = down_interruptible(&dlfb->urbs.limit_sem);
1816 		if (ret)
1817 			break;
1818 
1819 		spin_lock_irqsave(&dlfb->urbs.lock, flags);
1820 
1821 		node = dlfb->urbs.list.next; /* have reserved one with sem */
1822 		list_del_init(node);
1823 
1824 		spin_unlock_irqrestore(&dlfb->urbs.lock, flags);
1825 
1826 		unode = list_entry(node, struct urb_node, entry);
1827 		urb = unode->urb;
1828 
1829 		/* Free each separately allocated piece */
1830 		usb_free_coherent(urb->dev, dlfb->urbs.size,
1831 				  urb->transfer_buffer, urb->transfer_dma);
1832 		usb_free_urb(urb);
1833 		kfree(node);
1834 	}
1835 
1836 	dlfb->urbs.count = 0;
1837 }
1838 
1839 static int dlfb_alloc_urb_list(struct dlfb_data *dlfb, int count, size_t size)
1840 {
1841 	int i = 0;
1842 	struct urb *urb;
1843 	struct urb_node *unode;
1844 	char *buf;
1845 
1846 	spin_lock_init(&dlfb->urbs.lock);
1847 
1848 	dlfb->urbs.size = size;
1849 	INIT_LIST_HEAD(&dlfb->urbs.list);
1850 
1851 	while (i < count) {
1852 		unode = kzalloc(sizeof(*unode), GFP_KERNEL);
1853 		if (!unode)
1854 			break;
1855 		unode->dlfb = dlfb;
1856 
1857 		INIT_DELAYED_WORK(&unode->release_urb_work,
1858 			  dlfb_release_urb_work);
1859 
1860 		urb = usb_alloc_urb(0, GFP_KERNEL);
1861 		if (!urb) {
1862 			kfree(unode);
1863 			break;
1864 		}
1865 		unode->urb = urb;
1866 
1867 		buf = usb_alloc_coherent(dlfb->udev, MAX_TRANSFER, GFP_KERNEL,
1868 					 &urb->transfer_dma);
1869 		if (!buf) {
1870 			kfree(unode);
1871 			usb_free_urb(urb);
1872 			break;
1873 		}
1874 
1875 		/* urb->transfer_buffer_length set to actual before submit */
1876 		usb_fill_bulk_urb(urb, dlfb->udev, usb_sndbulkpipe(dlfb->udev, 1),
1877 			buf, size, dlfb_urb_completion, unode);
1878 		urb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;
1879 
1880 		list_add_tail(&unode->entry, &dlfb->urbs.list);
1881 
1882 		i++;
1883 	}
1884 
1885 	sema_init(&dlfb->urbs.limit_sem, i);
1886 	dlfb->urbs.count = i;
1887 	dlfb->urbs.available = i;
1888 
1889 	return i;
1890 }
1891 
1892 static struct urb *dlfb_get_urb(struct dlfb_data *dlfb)
1893 {
1894 	int ret;
1895 	struct list_head *entry;
1896 	struct urb_node *unode;
1897 	unsigned long flags;
1898 
1899 	/* Wait for an in-flight buffer to complete and get re-queued */
1900 	ret = down_timeout(&dlfb->urbs.limit_sem, GET_URB_TIMEOUT);
1901 	if (ret) {
1902 		atomic_set(&dlfb->lost_pixels, 1);
1903 		dev_warn(&dlfb->udev->dev,
1904 			 "wait for urb interrupted: %d available: %d\n",
1905 			 ret, dlfb->urbs.available);
1906 		return NULL;
1907 	}
1908 
1909 	spin_lock_irqsave(&dlfb->urbs.lock, flags);
1910 
1911 	BUG_ON(list_empty(&dlfb->urbs.list)); /* reserved one with limit_sem */
1912 	entry = dlfb->urbs.list.next;
1913 	list_del_init(entry);
1914 	dlfb->urbs.available--;
1915 
1916 	spin_unlock_irqrestore(&dlfb->urbs.lock, flags);
1917 
1918 	unode = list_entry(entry, struct urb_node, entry);
1919 	return unode->urb;
1920 }
1921 
1922 static int dlfb_submit_urb(struct dlfb_data *dlfb, struct urb *urb, size_t len)
1923 {
1924 	int ret;
1925 
1926 	BUG_ON(len > dlfb->urbs.size);
1927 
1928 	urb->transfer_buffer_length = len; /* set to actual payload len */
1929 	ret = usb_submit_urb(urb, GFP_KERNEL);
1930 	if (ret) {
1931 		dlfb_urb_completion(urb); /* because no one else will */
1932 		atomic_set(&dlfb->lost_pixels, 1);
1933 		dev_err(&dlfb->udev->dev, "submit urb error: %d\n", ret);
1934 	}
1935 	return ret;
1936 }
1937 
1938 module_param(console, bool, S_IWUSR | S_IRUSR | S_IWGRP | S_IRGRP);
1939 MODULE_PARM_DESC(console, "Allow fbcon to open framebuffer");
1940 
1941 module_param(fb_defio, bool, S_IWUSR | S_IRUSR | S_IWGRP | S_IRGRP);
1942 MODULE_PARM_DESC(fb_defio, "Page fault detection of mmap writes");
1943 
1944 module_param(shadow, bool, S_IWUSR | S_IRUSR | S_IWGRP | S_IRGRP);
1945 MODULE_PARM_DESC(shadow, "Shadow vid mem. Disable to save mem but lose perf");
1946 
1947 module_param(pixel_limit, int, S_IWUSR | S_IRUSR | S_IWGRP | S_IRGRP);
1948 MODULE_PARM_DESC(pixel_limit, "Force limit on max mode (in x*y pixels)");
1949 
1950 MODULE_AUTHOR("Roberto De Ioris <roberto@unbit.it>, "
1951 	      "Jaya Kumar <jayakumar.lkml@gmail.com>, "
1952 	      "Bernie Thompson <bernie@plugable.com>");
1953 MODULE_DESCRIPTION("DisplayLink kernel framebuffer driver");
1954 MODULE_LICENSE("GPL");
1955 
1956