xref: /openbmc/linux/drivers/video/fbdev/udlfb.c (revision 3213486f)
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/delay.h>
29 #include <asm/unaligned.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 struct dlfb_deferred_free {
76 	struct list_head list;
77 	void *mem;
78 };
79 
80 static int dlfb_realloc_framebuffer(struct dlfb_data *dlfb, struct fb_info *info, u32 new_len);
81 
82 /* dlfb keeps a list of urbs for efficient bulk transfers */
83 static void dlfb_urb_completion(struct urb *urb);
84 static struct urb *dlfb_get_urb(struct dlfb_data *dlfb);
85 static int dlfb_submit_urb(struct dlfb_data *dlfb, struct urb * urb, size_t len);
86 static int dlfb_alloc_urb_list(struct dlfb_data *dlfb, int count, size_t size);
87 static void dlfb_free_urb_list(struct dlfb_data *dlfb);
88 
89 /*
90  * All DisplayLink bulk operations start with 0xAF, followed by specific code
91  * All operations are written to buffers which then later get sent to device
92  */
93 static char *dlfb_set_register(char *buf, u8 reg, u8 val)
94 {
95 	*buf++ = 0xAF;
96 	*buf++ = 0x20;
97 	*buf++ = reg;
98 	*buf++ = val;
99 	return buf;
100 }
101 
102 static char *dlfb_vidreg_lock(char *buf)
103 {
104 	return dlfb_set_register(buf, 0xFF, 0x00);
105 }
106 
107 static char *dlfb_vidreg_unlock(char *buf)
108 {
109 	return dlfb_set_register(buf, 0xFF, 0xFF);
110 }
111 
112 /*
113  * Map FB_BLANK_* to DisplayLink register
114  * DLReg FB_BLANK_*
115  * ----- -----------------------------
116  *  0x00 FB_BLANK_UNBLANK (0)
117  *  0x01 FB_BLANK (1)
118  *  0x03 FB_BLANK_VSYNC_SUSPEND (2)
119  *  0x05 FB_BLANK_HSYNC_SUSPEND (3)
120  *  0x07 FB_BLANK_POWERDOWN (4) Note: requires modeset to come back
121  */
122 static char *dlfb_blanking(char *buf, int fb_blank)
123 {
124 	u8 reg;
125 
126 	switch (fb_blank) {
127 	case FB_BLANK_POWERDOWN:
128 		reg = 0x07;
129 		break;
130 	case FB_BLANK_HSYNC_SUSPEND:
131 		reg = 0x05;
132 		break;
133 	case FB_BLANK_VSYNC_SUSPEND:
134 		reg = 0x03;
135 		break;
136 	case FB_BLANK_NORMAL:
137 		reg = 0x01;
138 		break;
139 	default:
140 		reg = 0x00;
141 	}
142 
143 	buf = dlfb_set_register(buf, 0x1F, reg);
144 
145 	return buf;
146 }
147 
148 static char *dlfb_set_color_depth(char *buf, u8 selection)
149 {
150 	return dlfb_set_register(buf, 0x00, selection);
151 }
152 
153 static char *dlfb_set_base16bpp(char *wrptr, u32 base)
154 {
155 	/* the base pointer is 16 bits wide, 0x20 is hi byte. */
156 	wrptr = dlfb_set_register(wrptr, 0x20, base >> 16);
157 	wrptr = dlfb_set_register(wrptr, 0x21, base >> 8);
158 	return dlfb_set_register(wrptr, 0x22, base);
159 }
160 
161 /*
162  * DisplayLink HW has separate 16bpp and 8bpp framebuffers.
163  * In 24bpp modes, the low 323 RGB bits go in the 8bpp framebuffer
164  */
165 static char *dlfb_set_base8bpp(char *wrptr, u32 base)
166 {
167 	wrptr = dlfb_set_register(wrptr, 0x26, base >> 16);
168 	wrptr = dlfb_set_register(wrptr, 0x27, base >> 8);
169 	return dlfb_set_register(wrptr, 0x28, base);
170 }
171 
172 static char *dlfb_set_register_16(char *wrptr, u8 reg, u16 value)
173 {
174 	wrptr = dlfb_set_register(wrptr, reg, value >> 8);
175 	return dlfb_set_register(wrptr, reg+1, value);
176 }
177 
178 /*
179  * This is kind of weird because the controller takes some
180  * register values in a different byte order than other registers.
181  */
182 static char *dlfb_set_register_16be(char *wrptr, u8 reg, u16 value)
183 {
184 	wrptr = dlfb_set_register(wrptr, reg, value);
185 	return dlfb_set_register(wrptr, reg+1, value >> 8);
186 }
187 
188 /*
189  * LFSR is linear feedback shift register. The reason we have this is
190  * because the display controller needs to minimize the clock depth of
191  * various counters used in the display path. So this code reverses the
192  * provided value into the lfsr16 value by counting backwards to get
193  * the value that needs to be set in the hardware comparator to get the
194  * same actual count. This makes sense once you read above a couple of
195  * times and think about it from a hardware perspective.
196  */
197 static u16 dlfb_lfsr16(u16 actual_count)
198 {
199 	u32 lv = 0xFFFF; /* This is the lfsr value that the hw starts with */
200 
201 	while (actual_count--) {
202 		lv =	 ((lv << 1) |
203 			(((lv >> 15) ^ (lv >> 4) ^ (lv >> 2) ^ (lv >> 1)) & 1))
204 			& 0xFFFF;
205 	}
206 
207 	return (u16) lv;
208 }
209 
210 /*
211  * This does LFSR conversion on the value that is to be written.
212  * See LFSR explanation above for more detail.
213  */
214 static char *dlfb_set_register_lfsr16(char *wrptr, u8 reg, u16 value)
215 {
216 	return dlfb_set_register_16(wrptr, reg, dlfb_lfsr16(value));
217 }
218 
219 /*
220  * This takes a standard fbdev screeninfo struct and all of its monitor mode
221  * details and converts them into the DisplayLink equivalent register commands.
222  */
223 static char *dlfb_set_vid_cmds(char *wrptr, struct fb_var_screeninfo *var)
224 {
225 	u16 xds, yds;
226 	u16 xde, yde;
227 	u16 yec;
228 
229 	/* x display start */
230 	xds = var->left_margin + var->hsync_len;
231 	wrptr = dlfb_set_register_lfsr16(wrptr, 0x01, xds);
232 	/* x display end */
233 	xde = xds + var->xres;
234 	wrptr = dlfb_set_register_lfsr16(wrptr, 0x03, xde);
235 
236 	/* y display start */
237 	yds = var->upper_margin + var->vsync_len;
238 	wrptr = dlfb_set_register_lfsr16(wrptr, 0x05, yds);
239 	/* y display end */
240 	yde = yds + var->yres;
241 	wrptr = dlfb_set_register_lfsr16(wrptr, 0x07, yde);
242 
243 	/* x end count is active + blanking - 1 */
244 	wrptr = dlfb_set_register_lfsr16(wrptr, 0x09,
245 			xde + var->right_margin - 1);
246 
247 	/* libdlo hardcodes hsync start to 1 */
248 	wrptr = dlfb_set_register_lfsr16(wrptr, 0x0B, 1);
249 
250 	/* hsync end is width of sync pulse + 1 */
251 	wrptr = dlfb_set_register_lfsr16(wrptr, 0x0D, var->hsync_len + 1);
252 
253 	/* hpixels is active pixels */
254 	wrptr = dlfb_set_register_16(wrptr, 0x0F, var->xres);
255 
256 	/* yendcount is vertical active + vertical blanking */
257 	yec = var->yres + var->upper_margin + var->lower_margin +
258 			var->vsync_len;
259 	wrptr = dlfb_set_register_lfsr16(wrptr, 0x11, yec);
260 
261 	/* libdlo hardcodes vsync start to 0 */
262 	wrptr = dlfb_set_register_lfsr16(wrptr, 0x13, 0);
263 
264 	/* vsync end is width of vsync pulse */
265 	wrptr = dlfb_set_register_lfsr16(wrptr, 0x15, var->vsync_len);
266 
267 	/* vpixels is active pixels */
268 	wrptr = dlfb_set_register_16(wrptr, 0x17, var->yres);
269 
270 	/* convert picoseconds to 5kHz multiple for pclk5k = x * 1E12/5k */
271 	wrptr = dlfb_set_register_16be(wrptr, 0x1B,
272 			200*1000*1000/var->pixclock);
273 
274 	return wrptr;
275 }
276 
277 /*
278  * This takes a standard fbdev screeninfo struct that was fetched or prepared
279  * and then generates the appropriate command sequence that then drives the
280  * display controller.
281  */
282 static int dlfb_set_video_mode(struct dlfb_data *dlfb,
283 				struct fb_var_screeninfo *var)
284 {
285 	char *buf;
286 	char *wrptr;
287 	int retval;
288 	int writesize;
289 	struct urb *urb;
290 
291 	if (!atomic_read(&dlfb->usb_active))
292 		return -EPERM;
293 
294 	urb = dlfb_get_urb(dlfb);
295 	if (!urb)
296 		return -ENOMEM;
297 
298 	buf = (char *) urb->transfer_buffer;
299 
300 	/*
301 	* This first section has to do with setting the base address on the
302 	* controller * associated with the display. There are 2 base
303 	* pointers, currently, we only * use the 16 bpp segment.
304 	*/
305 	wrptr = dlfb_vidreg_lock(buf);
306 	wrptr = dlfb_set_color_depth(wrptr, 0x00);
307 	/* set base for 16bpp segment to 0 */
308 	wrptr = dlfb_set_base16bpp(wrptr, 0);
309 	/* set base for 8bpp segment to end of fb */
310 	wrptr = dlfb_set_base8bpp(wrptr, dlfb->info->fix.smem_len);
311 
312 	wrptr = dlfb_set_vid_cmds(wrptr, var);
313 	wrptr = dlfb_blanking(wrptr, FB_BLANK_UNBLANK);
314 	wrptr = dlfb_vidreg_unlock(wrptr);
315 
316 	writesize = wrptr - buf;
317 
318 	retval = dlfb_submit_urb(dlfb, urb, writesize);
319 
320 	dlfb->blank_mode = FB_BLANK_UNBLANK;
321 
322 	return retval;
323 }
324 
325 static int dlfb_ops_mmap(struct fb_info *info, struct vm_area_struct *vma)
326 {
327 	unsigned long start = vma->vm_start;
328 	unsigned long size = vma->vm_end - vma->vm_start;
329 	unsigned long offset = vma->vm_pgoff << PAGE_SHIFT;
330 	unsigned long page, pos;
331 
332 	if (vma->vm_pgoff > (~0UL >> PAGE_SHIFT))
333 		return -EINVAL;
334 	if (size > info->fix.smem_len)
335 		return -EINVAL;
336 	if (offset > info->fix.smem_len - size)
337 		return -EINVAL;
338 
339 	pos = (unsigned long)info->fix.smem_start + offset;
340 
341 	dev_dbg(info->dev, "mmap() framebuffer addr:%lu size:%lu\n",
342 		pos, size);
343 
344 	while (size > 0) {
345 		page = vmalloc_to_pfn((void *)pos);
346 		if (remap_pfn_range(vma, start, page, PAGE_SIZE, PAGE_SHARED))
347 			return -EAGAIN;
348 
349 		start += PAGE_SIZE;
350 		pos += PAGE_SIZE;
351 		if (size > PAGE_SIZE)
352 			size -= PAGE_SIZE;
353 		else
354 			size = 0;
355 	}
356 
357 	return 0;
358 }
359 
360 /*
361  * Trims identical data from front and back of line
362  * Sets new front buffer address and width
363  * And returns byte count of identical pixels
364  * Assumes CPU natural alignment (unsigned long)
365  * for back and front buffer ptrs and width
366  */
367 static int dlfb_trim_hline(const u8 *bback, const u8 **bfront, int *width_bytes)
368 {
369 	int j, k;
370 	const unsigned long *back = (const unsigned long *) bback;
371 	const unsigned long *front = (const unsigned long *) *bfront;
372 	const int width = *width_bytes / sizeof(unsigned long);
373 	int identical = width;
374 	int start = width;
375 	int end = width;
376 
377 	for (j = 0; j < width; j++) {
378 		if (back[j] != front[j]) {
379 			start = j;
380 			break;
381 		}
382 	}
383 
384 	for (k = width - 1; k > j; k--) {
385 		if (back[k] != front[k]) {
386 			end = k+1;
387 			break;
388 		}
389 	}
390 
391 	identical = start + (width - end);
392 	*bfront = (u8 *) &front[start];
393 	*width_bytes = (end - start) * sizeof(unsigned long);
394 
395 	return identical * sizeof(unsigned long);
396 }
397 
398 /*
399  * Render a command stream for an encoded horizontal line segment of pixels.
400  *
401  * A command buffer holds several commands.
402  * It always begins with a fresh command header
403  * (the protocol doesn't require this, but we enforce it to allow
404  * multiple buffers to be potentially encoded and sent in parallel).
405  * A single command encodes one contiguous horizontal line of pixels
406  *
407  * The function relies on the client to do all allocation, so that
408  * rendering can be done directly to output buffers (e.g. USB URBs).
409  * The function fills the supplied command buffer, providing information
410  * on where it left off, so the client may call in again with additional
411  * buffers if the line will take several buffers to complete.
412  *
413  * A single command can transmit a maximum of 256 pixels,
414  * regardless of the compression ratio (protocol design limit).
415  * To the hardware, 0 for a size byte means 256
416  *
417  * Rather than 256 pixel commands which are either rl or raw encoded,
418  * the rlx command simply assumes alternating raw and rl spans within one cmd.
419  * This has a slightly larger header overhead, but produces more even results.
420  * It also processes all data (read and write) in a single pass.
421  * Performance benchmarks of common cases show it having just slightly better
422  * compression than 256 pixel raw or rle commands, with similar CPU consumpion.
423  * But for very rl friendly data, will compress not quite as well.
424  */
425 static void dlfb_compress_hline(
426 	const uint16_t **pixel_start_ptr,
427 	const uint16_t *const pixel_end,
428 	uint32_t *device_address_ptr,
429 	uint8_t **command_buffer_ptr,
430 	const uint8_t *const cmd_buffer_end,
431 	unsigned long back_buffer_offset,
432 	int *ident_ptr)
433 {
434 	const uint16_t *pixel = *pixel_start_ptr;
435 	uint32_t dev_addr  = *device_address_ptr;
436 	uint8_t *cmd = *command_buffer_ptr;
437 
438 	while ((pixel_end > pixel) &&
439 	       (cmd_buffer_end - MIN_RLX_CMD_BYTES > cmd)) {
440 		uint8_t *raw_pixels_count_byte = NULL;
441 		uint8_t *cmd_pixels_count_byte = NULL;
442 		const uint16_t *raw_pixel_start = NULL;
443 		const uint16_t *cmd_pixel_start, *cmd_pixel_end = NULL;
444 
445 		if (back_buffer_offset &&
446 		    *pixel == *(u16 *)((u8 *)pixel + back_buffer_offset)) {
447 			pixel++;
448 			dev_addr += BPP;
449 			(*ident_ptr)++;
450 			continue;
451 		}
452 
453 		*cmd++ = 0xAF;
454 		*cmd++ = 0x6B;
455 		*cmd++ = dev_addr >> 16;
456 		*cmd++ = dev_addr >> 8;
457 		*cmd++ = dev_addr;
458 
459 		cmd_pixels_count_byte = cmd++; /*  we'll know this later */
460 		cmd_pixel_start = pixel;
461 
462 		raw_pixels_count_byte = cmd++; /*  we'll know this later */
463 		raw_pixel_start = pixel;
464 
465 		cmd_pixel_end = pixel + min3(MAX_CMD_PIXELS + 1UL,
466 					(unsigned long)(pixel_end - pixel),
467 					(unsigned long)(cmd_buffer_end - 1 - cmd) / BPP);
468 
469 		if (back_buffer_offset) {
470 			/* note: the framebuffer may change under us, so we must test for underflow */
471 			while (cmd_pixel_end - 1 > pixel &&
472 			       *(cmd_pixel_end - 1) == *(u16 *)((u8 *)(cmd_pixel_end - 1) + back_buffer_offset))
473 				cmd_pixel_end--;
474 		}
475 
476 		while (pixel < cmd_pixel_end) {
477 			const uint16_t * const repeating_pixel = pixel;
478 			u16 pixel_value = *pixel;
479 
480 			put_unaligned_be16(pixel_value, cmd);
481 			if (back_buffer_offset)
482 				*(u16 *)((u8 *)pixel + back_buffer_offset) = pixel_value;
483 			cmd += 2;
484 			pixel++;
485 
486 			if (unlikely((pixel < cmd_pixel_end) &&
487 				     (*pixel == pixel_value))) {
488 				/* go back and fill in raw pixel count */
489 				*raw_pixels_count_byte = ((repeating_pixel -
490 						raw_pixel_start) + 1) & 0xFF;
491 
492 				do {
493 					if (back_buffer_offset)
494 						*(u16 *)((u8 *)pixel + back_buffer_offset) = pixel_value;
495 					pixel++;
496 				} while ((pixel < cmd_pixel_end) &&
497 					 (*pixel == pixel_value));
498 
499 				/* immediately after raw data is repeat byte */
500 				*cmd++ = ((pixel - repeating_pixel) - 1) & 0xFF;
501 
502 				/* Then start another raw pixel span */
503 				raw_pixel_start = pixel;
504 				raw_pixels_count_byte = cmd++;
505 			}
506 		}
507 
508 		if (pixel > raw_pixel_start) {
509 			/* finalize last RAW span */
510 			*raw_pixels_count_byte = (pixel-raw_pixel_start) & 0xFF;
511 		} else {
512 			/* undo unused byte */
513 			cmd--;
514 		}
515 
516 		*cmd_pixels_count_byte = (pixel - cmd_pixel_start) & 0xFF;
517 		dev_addr += (u8 *)pixel - (u8 *)cmd_pixel_start;
518 	}
519 
520 	if (cmd_buffer_end - MIN_RLX_CMD_BYTES <= cmd) {
521 		/* Fill leftover bytes with no-ops */
522 		if (cmd_buffer_end > cmd)
523 			memset(cmd, 0xAF, cmd_buffer_end - cmd);
524 		cmd = (uint8_t *) cmd_buffer_end;
525 	}
526 
527 	*command_buffer_ptr = cmd;
528 	*pixel_start_ptr = pixel;
529 	*device_address_ptr = dev_addr;
530 }
531 
532 /*
533  * There are 3 copies of every pixel: The front buffer that the fbdev
534  * client renders to, the actual framebuffer across the USB bus in hardware
535  * (that we can only write to, slowly, and can never read), and (optionally)
536  * our shadow copy that tracks what's been sent to that hardware buffer.
537  */
538 static int dlfb_render_hline(struct dlfb_data *dlfb, struct urb **urb_ptr,
539 			      const char *front, char **urb_buf_ptr,
540 			      u32 byte_offset, u32 byte_width,
541 			      int *ident_ptr, int *sent_ptr)
542 {
543 	const u8 *line_start, *line_end, *next_pixel;
544 	u32 dev_addr = dlfb->base16 + byte_offset;
545 	struct urb *urb = *urb_ptr;
546 	u8 *cmd = *urb_buf_ptr;
547 	u8 *cmd_end = (u8 *) urb->transfer_buffer + urb->transfer_buffer_length;
548 	unsigned long back_buffer_offset = 0;
549 
550 	line_start = (u8 *) (front + byte_offset);
551 	next_pixel = line_start;
552 	line_end = next_pixel + byte_width;
553 
554 	if (dlfb->backing_buffer) {
555 		int offset;
556 		const u8 *back_start = (u8 *) (dlfb->backing_buffer
557 						+ byte_offset);
558 
559 		back_buffer_offset = (unsigned long)back_start - (unsigned long)line_start;
560 
561 		*ident_ptr += dlfb_trim_hline(back_start, &next_pixel,
562 			&byte_width);
563 
564 		offset = next_pixel - line_start;
565 		line_end = next_pixel + byte_width;
566 		dev_addr += offset;
567 		back_start += offset;
568 		line_start += offset;
569 	}
570 
571 	while (next_pixel < line_end) {
572 
573 		dlfb_compress_hline((const uint16_t **) &next_pixel,
574 			     (const uint16_t *) line_end, &dev_addr,
575 			(u8 **) &cmd, (u8 *) cmd_end, back_buffer_offset,
576 			ident_ptr);
577 
578 		if (cmd >= cmd_end) {
579 			int len = cmd - (u8 *) urb->transfer_buffer;
580 			if (dlfb_submit_urb(dlfb, urb, len))
581 				return 1; /* lost pixels is set */
582 			*sent_ptr += len;
583 			urb = dlfb_get_urb(dlfb);
584 			if (!urb)
585 				return 1; /* lost_pixels is set */
586 			*urb_ptr = urb;
587 			cmd = urb->transfer_buffer;
588 			cmd_end = &cmd[urb->transfer_buffer_length];
589 		}
590 	}
591 
592 	*urb_buf_ptr = cmd;
593 
594 	return 0;
595 }
596 
597 static int dlfb_handle_damage(struct dlfb_data *dlfb, int x, int y,
598 	       int width, int height, char *data)
599 {
600 	int i, ret;
601 	char *cmd;
602 	cycles_t start_cycles, end_cycles;
603 	int bytes_sent = 0;
604 	int bytes_identical = 0;
605 	struct urb *urb;
606 	int aligned_x;
607 
608 	start_cycles = get_cycles();
609 
610 	aligned_x = DL_ALIGN_DOWN(x, sizeof(unsigned long));
611 	width = DL_ALIGN_UP(width + (x-aligned_x), sizeof(unsigned long));
612 	x = aligned_x;
613 
614 	if ((width <= 0) ||
615 	    (x + width > dlfb->info->var.xres) ||
616 	    (y + height > dlfb->info->var.yres))
617 		return -EINVAL;
618 
619 	if (!atomic_read(&dlfb->usb_active))
620 		return 0;
621 
622 	urb = dlfb_get_urb(dlfb);
623 	if (!urb)
624 		return 0;
625 	cmd = urb->transfer_buffer;
626 
627 	for (i = y; i < y + height ; i++) {
628 		const int line_offset = dlfb->info->fix.line_length * i;
629 		const int byte_offset = line_offset + (x * BPP);
630 
631 		if (dlfb_render_hline(dlfb, &urb,
632 				      (char *) dlfb->info->fix.smem_start,
633 				      &cmd, byte_offset, width * BPP,
634 				      &bytes_identical, &bytes_sent))
635 			goto error;
636 	}
637 
638 	if (cmd > (char *) urb->transfer_buffer) {
639 		int len;
640 		if (cmd < (char *) urb->transfer_buffer + urb->transfer_buffer_length)
641 			*cmd++ = 0xAF;
642 		/* Send partial buffer remaining before exiting */
643 		len = cmd - (char *) urb->transfer_buffer;
644 		ret = dlfb_submit_urb(dlfb, urb, len);
645 		bytes_sent += len;
646 	} else
647 		dlfb_urb_completion(urb);
648 
649 error:
650 	atomic_add(bytes_sent, &dlfb->bytes_sent);
651 	atomic_add(bytes_identical, &dlfb->bytes_identical);
652 	atomic_add(width*height*2, &dlfb->bytes_rendered);
653 	end_cycles = get_cycles();
654 	atomic_add(((unsigned int) ((end_cycles - start_cycles)
655 		    >> 10)), /* Kcycles */
656 		   &dlfb->cpu_kcycles_used);
657 
658 	return 0;
659 }
660 
661 /*
662  * Path triggered by usermode clients who write to filesystem
663  * e.g. cat filename > /dev/fb1
664  * Not used by X Windows or text-mode console. But useful for testing.
665  * Slow because of extra copy and we must assume all pixels dirty.
666  */
667 static ssize_t dlfb_ops_write(struct fb_info *info, const char __user *buf,
668 			  size_t count, loff_t *ppos)
669 {
670 	ssize_t result;
671 	struct dlfb_data *dlfb = info->par;
672 	u32 offset = (u32) *ppos;
673 
674 	result = fb_sys_write(info, buf, count, ppos);
675 
676 	if (result > 0) {
677 		int start = max((int)(offset / info->fix.line_length), 0);
678 		int lines = min((u32)((result / info->fix.line_length) + 1),
679 				(u32)info->var.yres);
680 
681 		dlfb_handle_damage(dlfb, 0, start, info->var.xres,
682 			lines, info->screen_base);
683 	}
684 
685 	return result;
686 }
687 
688 /* hardware has native COPY command (see libdlo), but not worth it for fbcon */
689 static void dlfb_ops_copyarea(struct fb_info *info,
690 				const struct fb_copyarea *area)
691 {
692 
693 	struct dlfb_data *dlfb = info->par;
694 
695 	sys_copyarea(info, area);
696 
697 	dlfb_handle_damage(dlfb, area->dx, area->dy,
698 			area->width, area->height, info->screen_base);
699 }
700 
701 static void dlfb_ops_imageblit(struct fb_info *info,
702 				const struct fb_image *image)
703 {
704 	struct dlfb_data *dlfb = info->par;
705 
706 	sys_imageblit(info, image);
707 
708 	dlfb_handle_damage(dlfb, image->dx, image->dy,
709 			image->width, image->height, info->screen_base);
710 }
711 
712 static void dlfb_ops_fillrect(struct fb_info *info,
713 			  const struct fb_fillrect *rect)
714 {
715 	struct dlfb_data *dlfb = info->par;
716 
717 	sys_fillrect(info, rect);
718 
719 	dlfb_handle_damage(dlfb, rect->dx, rect->dy, rect->width,
720 			      rect->height, info->screen_base);
721 }
722 
723 /*
724  * NOTE: fb_defio.c is holding info->fbdefio.mutex
725  *   Touching ANY framebuffer memory that triggers a page fault
726  *   in fb_defio will cause a deadlock, when it also tries to
727  *   grab the same mutex.
728  */
729 static void dlfb_dpy_deferred_io(struct fb_info *info,
730 				struct list_head *pagelist)
731 {
732 	struct page *cur;
733 	struct fb_deferred_io *fbdefio = info->fbdefio;
734 	struct dlfb_data *dlfb = info->par;
735 	struct urb *urb;
736 	char *cmd;
737 	cycles_t start_cycles, end_cycles;
738 	int bytes_sent = 0;
739 	int bytes_identical = 0;
740 	int bytes_rendered = 0;
741 
742 	if (!fb_defio)
743 		return;
744 
745 	if (!atomic_read(&dlfb->usb_active))
746 		return;
747 
748 	start_cycles = get_cycles();
749 
750 	urb = dlfb_get_urb(dlfb);
751 	if (!urb)
752 		return;
753 
754 	cmd = urb->transfer_buffer;
755 
756 	/* walk the written page list and render each to device */
757 	list_for_each_entry(cur, &fbdefio->pagelist, lru) {
758 
759 		if (dlfb_render_hline(dlfb, &urb, (char *) info->fix.smem_start,
760 				  &cmd, cur->index << PAGE_SHIFT,
761 				  PAGE_SIZE, &bytes_identical, &bytes_sent))
762 			goto error;
763 		bytes_rendered += PAGE_SIZE;
764 	}
765 
766 	if (cmd > (char *) urb->transfer_buffer) {
767 		int len;
768 		if (cmd < (char *) urb->transfer_buffer + urb->transfer_buffer_length)
769 			*cmd++ = 0xAF;
770 		/* Send partial buffer remaining before exiting */
771 		len = cmd - (char *) urb->transfer_buffer;
772 		dlfb_submit_urb(dlfb, urb, len);
773 		bytes_sent += len;
774 	} else
775 		dlfb_urb_completion(urb);
776 
777 error:
778 	atomic_add(bytes_sent, &dlfb->bytes_sent);
779 	atomic_add(bytes_identical, &dlfb->bytes_identical);
780 	atomic_add(bytes_rendered, &dlfb->bytes_rendered);
781 	end_cycles = get_cycles();
782 	atomic_add(((unsigned int) ((end_cycles - start_cycles)
783 		    >> 10)), /* Kcycles */
784 		   &dlfb->cpu_kcycles_used);
785 }
786 
787 static int dlfb_get_edid(struct dlfb_data *dlfb, char *edid, int len)
788 {
789 	int i, ret;
790 	char *rbuf;
791 
792 	rbuf = kmalloc(2, GFP_KERNEL);
793 	if (!rbuf)
794 		return 0;
795 
796 	for (i = 0; i < len; i++) {
797 		ret = usb_control_msg(dlfb->udev,
798 				      usb_rcvctrlpipe(dlfb->udev, 0), 0x02,
799 				      (0x80 | (0x02 << 5)), i << 8, 0xA1,
800 				      rbuf, 2, USB_CTRL_GET_TIMEOUT);
801 		if (ret < 2) {
802 			dev_err(&dlfb->udev->dev,
803 				"Read EDID byte %d failed: %d\n", i, ret);
804 			i--;
805 			break;
806 		}
807 		edid[i] = rbuf[1];
808 	}
809 
810 	kfree(rbuf);
811 
812 	return i;
813 }
814 
815 static int dlfb_ops_ioctl(struct fb_info *info, unsigned int cmd,
816 				unsigned long arg)
817 {
818 
819 	struct dlfb_data *dlfb = info->par;
820 
821 	if (!atomic_read(&dlfb->usb_active))
822 		return 0;
823 
824 	/* TODO: Update X server to get this from sysfs instead */
825 	if (cmd == DLFB_IOCTL_RETURN_EDID) {
826 		void __user *edid = (void __user *)arg;
827 		if (copy_to_user(edid, dlfb->edid, dlfb->edid_size))
828 			return -EFAULT;
829 		return 0;
830 	}
831 
832 	/* TODO: Help propose a standard fb.h ioctl to report mmap damage */
833 	if (cmd == DLFB_IOCTL_REPORT_DAMAGE) {
834 		struct dloarea area;
835 
836 		if (copy_from_user(&area, (void __user *)arg,
837 				  sizeof(struct dloarea)))
838 			return -EFAULT;
839 
840 		/*
841 		 * If we have a damage-aware client, turn fb_defio "off"
842 		 * To avoid perf imact of unnecessary page fault handling.
843 		 * Done by resetting the delay for this fb_info to a very
844 		 * long period. Pages will become writable and stay that way.
845 		 * Reset to normal value when all clients have closed this fb.
846 		 */
847 		if (info->fbdefio)
848 			info->fbdefio->delay = DL_DEFIO_WRITE_DISABLE;
849 
850 		if (area.x < 0)
851 			area.x = 0;
852 
853 		if (area.x > info->var.xres)
854 			area.x = info->var.xres;
855 
856 		if (area.y < 0)
857 			area.y = 0;
858 
859 		if (area.y > info->var.yres)
860 			area.y = info->var.yres;
861 
862 		dlfb_handle_damage(dlfb, area.x, area.y, area.w, area.h,
863 			   info->screen_base);
864 	}
865 
866 	return 0;
867 }
868 
869 /* taken from vesafb */
870 static int
871 dlfb_ops_setcolreg(unsigned regno, unsigned red, unsigned green,
872 	       unsigned blue, unsigned transp, struct fb_info *info)
873 {
874 	int err = 0;
875 
876 	if (regno >= info->cmap.len)
877 		return 1;
878 
879 	if (regno < 16) {
880 		if (info->var.red.offset == 10) {
881 			/* 1:5:5:5 */
882 			((u32 *) (info->pseudo_palette))[regno] =
883 			    ((red & 0xf800) >> 1) |
884 			    ((green & 0xf800) >> 6) | ((blue & 0xf800) >> 11);
885 		} else {
886 			/* 0:5:6:5 */
887 			((u32 *) (info->pseudo_palette))[regno] =
888 			    ((red & 0xf800)) |
889 			    ((green & 0xfc00) >> 5) | ((blue & 0xf800) >> 11);
890 		}
891 	}
892 
893 	return err;
894 }
895 
896 /*
897  * It's common for several clients to have framebuffer open simultaneously.
898  * e.g. both fbcon and X. Makes things interesting.
899  * Assumes caller is holding info->lock (for open and release at least)
900  */
901 static int dlfb_ops_open(struct fb_info *info, int user)
902 {
903 	struct dlfb_data *dlfb = info->par;
904 
905 	/*
906 	 * fbcon aggressively connects to first framebuffer it finds,
907 	 * preventing other clients (X) from working properly. Usually
908 	 * not what the user wants. Fail by default with option to enable.
909 	 */
910 	if ((user == 0) && (!console))
911 		return -EBUSY;
912 
913 	/* If the USB device is gone, we don't accept new opens */
914 	if (dlfb->virtualized)
915 		return -ENODEV;
916 
917 	dlfb->fb_count++;
918 
919 	if (fb_defio && (info->fbdefio == NULL)) {
920 		/* enable defio at last moment if not disabled by client */
921 
922 		struct fb_deferred_io *fbdefio;
923 
924 		fbdefio = kzalloc(sizeof(struct fb_deferred_io), GFP_KERNEL);
925 
926 		if (fbdefio) {
927 			fbdefio->delay = DL_DEFIO_WRITE_DELAY;
928 			fbdefio->deferred_io = dlfb_dpy_deferred_io;
929 		}
930 
931 		info->fbdefio = fbdefio;
932 		fb_deferred_io_init(info);
933 	}
934 
935 	dev_dbg(info->dev, "open, user=%d fb_info=%p count=%d\n",
936 		user, info, dlfb->fb_count);
937 
938 	return 0;
939 }
940 
941 static void dlfb_ops_destroy(struct fb_info *info)
942 {
943 	struct dlfb_data *dlfb = info->par;
944 
945 	if (info->cmap.len != 0)
946 		fb_dealloc_cmap(&info->cmap);
947 	if (info->monspecs.modedb)
948 		fb_destroy_modedb(info->monspecs.modedb);
949 	vfree(info->screen_base);
950 
951 	fb_destroy_modelist(&info->modelist);
952 
953 	while (!list_empty(&dlfb->deferred_free)) {
954 		struct dlfb_deferred_free *d = list_entry(dlfb->deferred_free.next, struct dlfb_deferred_free, list);
955 		list_del(&d->list);
956 		vfree(d->mem);
957 		kfree(d);
958 	}
959 	vfree(dlfb->backing_buffer);
960 	kfree(dlfb->edid);
961 	usb_put_dev(dlfb->udev);
962 	kfree(dlfb);
963 
964 	/* Assume info structure is freed after this point */
965 	framebuffer_release(info);
966 }
967 
968 /*
969  * Assumes caller is holding info->lock mutex (for open and release at least)
970  */
971 static int dlfb_ops_release(struct fb_info *info, int user)
972 {
973 	struct dlfb_data *dlfb = info->par;
974 
975 	dlfb->fb_count--;
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 	return 0;
987 }
988 
989 /*
990  * Check whether a video mode is supported by the DisplayLink chip
991  * We start from monitor's modes, so don't need to filter that here
992  */
993 static int dlfb_is_valid_mode(struct fb_videomode *mode, struct dlfb_data *dlfb)
994 {
995 	if (mode->xres * mode->yres > dlfb->sku_pixel_limit)
996 		return 0;
997 
998 	return 1;
999 }
1000 
1001 static void dlfb_var_color_format(struct fb_var_screeninfo *var)
1002 {
1003 	const struct fb_bitfield red = { 11, 5, 0 };
1004 	const struct fb_bitfield green = { 5, 6, 0 };
1005 	const struct fb_bitfield blue = { 0, 5, 0 };
1006 
1007 	var->bits_per_pixel = 16;
1008 	var->red = red;
1009 	var->green = green;
1010 	var->blue = blue;
1011 }
1012 
1013 static int dlfb_ops_check_var(struct fb_var_screeninfo *var,
1014 				struct fb_info *info)
1015 {
1016 	struct fb_videomode mode;
1017 	struct dlfb_data *dlfb = info->par;
1018 
1019 	/* set device-specific elements of var unrelated to mode */
1020 	dlfb_var_color_format(var);
1021 
1022 	fb_var_to_videomode(&mode, var);
1023 
1024 	if (!dlfb_is_valid_mode(&mode, dlfb))
1025 		return -EINVAL;
1026 
1027 	return 0;
1028 }
1029 
1030 static int dlfb_ops_set_par(struct fb_info *info)
1031 {
1032 	struct dlfb_data *dlfb = info->par;
1033 	int result;
1034 	u16 *pix_framebuffer;
1035 	int i;
1036 	struct fb_var_screeninfo fvs;
1037 	u32 line_length = info->var.xres * (info->var.bits_per_pixel / 8);
1038 
1039 	/* clear the activate field because it causes spurious miscompares */
1040 	fvs = info->var;
1041 	fvs.activate = 0;
1042 	fvs.vmode &= ~FB_VMODE_SMOOTH_XPAN;
1043 
1044 	if (!memcmp(&dlfb->current_mode, &fvs, sizeof(struct fb_var_screeninfo)))
1045 		return 0;
1046 
1047 	result = dlfb_realloc_framebuffer(dlfb, info, info->var.yres * line_length);
1048 	if (result)
1049 		return result;
1050 
1051 	result = dlfb_set_video_mode(dlfb, &info->var);
1052 
1053 	if (result)
1054 		return result;
1055 
1056 	dlfb->current_mode = fvs;
1057 	info->fix.line_length = line_length;
1058 
1059 	if (dlfb->fb_count == 0) {
1060 
1061 		/* paint greenscreen */
1062 
1063 		pix_framebuffer = (u16 *) info->screen_base;
1064 		for (i = 0; i < info->fix.smem_len / 2; i++)
1065 			pix_framebuffer[i] = 0x37e6;
1066 	}
1067 
1068 	dlfb_handle_damage(dlfb, 0, 0, info->var.xres, info->var.yres,
1069 			   info->screen_base);
1070 
1071 	return 0;
1072 }
1073 
1074 /* To fonzi the jukebox (e.g. make blanking changes take effect) */
1075 static char *dlfb_dummy_render(char *buf)
1076 {
1077 	*buf++ = 0xAF;
1078 	*buf++ = 0x6A; /* copy */
1079 	*buf++ = 0x00; /* from address*/
1080 	*buf++ = 0x00;
1081 	*buf++ = 0x00;
1082 	*buf++ = 0x01; /* one pixel */
1083 	*buf++ = 0x00; /* to address */
1084 	*buf++ = 0x00;
1085 	*buf++ = 0x00;
1086 	return buf;
1087 }
1088 
1089 /*
1090  * In order to come back from full DPMS off, we need to set the mode again
1091  */
1092 static int dlfb_ops_blank(int blank_mode, struct fb_info *info)
1093 {
1094 	struct dlfb_data *dlfb = info->par;
1095 	char *bufptr;
1096 	struct urb *urb;
1097 
1098 	dev_dbg(info->dev, "blank, mode %d --> %d\n",
1099 		dlfb->blank_mode, blank_mode);
1100 
1101 	if ((dlfb->blank_mode == FB_BLANK_POWERDOWN) &&
1102 	    (blank_mode != FB_BLANK_POWERDOWN)) {
1103 
1104 		/* returning from powerdown requires a fresh modeset */
1105 		dlfb_set_video_mode(dlfb, &info->var);
1106 	}
1107 
1108 	urb = dlfb_get_urb(dlfb);
1109 	if (!urb)
1110 		return 0;
1111 
1112 	bufptr = (char *) urb->transfer_buffer;
1113 	bufptr = dlfb_vidreg_lock(bufptr);
1114 	bufptr = dlfb_blanking(bufptr, blank_mode);
1115 	bufptr = dlfb_vidreg_unlock(bufptr);
1116 
1117 	/* seems like a render op is needed to have blank change take effect */
1118 	bufptr = dlfb_dummy_render(bufptr);
1119 
1120 	dlfb_submit_urb(dlfb, urb, bufptr -
1121 			(char *) urb->transfer_buffer);
1122 
1123 	dlfb->blank_mode = blank_mode;
1124 
1125 	return 0;
1126 }
1127 
1128 static struct fb_ops dlfb_ops = {
1129 	.owner = THIS_MODULE,
1130 	.fb_read = fb_sys_read,
1131 	.fb_write = dlfb_ops_write,
1132 	.fb_setcolreg = dlfb_ops_setcolreg,
1133 	.fb_fillrect = dlfb_ops_fillrect,
1134 	.fb_copyarea = dlfb_ops_copyarea,
1135 	.fb_imageblit = dlfb_ops_imageblit,
1136 	.fb_mmap = dlfb_ops_mmap,
1137 	.fb_ioctl = dlfb_ops_ioctl,
1138 	.fb_open = dlfb_ops_open,
1139 	.fb_release = dlfb_ops_release,
1140 	.fb_blank = dlfb_ops_blank,
1141 	.fb_check_var = dlfb_ops_check_var,
1142 	.fb_set_par = dlfb_ops_set_par,
1143 	.fb_destroy = dlfb_ops_destroy,
1144 };
1145 
1146 
1147 static void dlfb_deferred_vfree(struct dlfb_data *dlfb, void *mem)
1148 {
1149 	struct dlfb_deferred_free *d = kmalloc(sizeof(struct dlfb_deferred_free), GFP_KERNEL);
1150 	if (!d)
1151 		return;
1152 	d->mem = mem;
1153 	list_add(&d->list, &dlfb->deferred_free);
1154 }
1155 
1156 /*
1157  * Assumes &info->lock held by caller
1158  * Assumes no active clients have framebuffer open
1159  */
1160 static int dlfb_realloc_framebuffer(struct dlfb_data *dlfb, struct fb_info *info, u32 new_len)
1161 {
1162 	u32 old_len = info->fix.smem_len;
1163 	const void *old_fb = (const void __force *)info->screen_base;
1164 	unsigned char *new_fb;
1165 	unsigned char *new_back = NULL;
1166 
1167 	new_len = PAGE_ALIGN(new_len);
1168 
1169 	if (new_len > old_len) {
1170 		/*
1171 		 * Alloc system memory for virtual framebuffer
1172 		 */
1173 		new_fb = vmalloc(new_len);
1174 		if (!new_fb) {
1175 			dev_err(info->dev, "Virtual framebuffer alloc failed\n");
1176 			return -ENOMEM;
1177 		}
1178 		memset(new_fb, 0xff, new_len);
1179 
1180 		if (info->screen_base) {
1181 			memcpy(new_fb, old_fb, old_len);
1182 			dlfb_deferred_vfree(dlfb, (void __force *)info->screen_base);
1183 		}
1184 
1185 		info->screen_base = (char __iomem *)new_fb;
1186 		info->fix.smem_len = new_len;
1187 		info->fix.smem_start = (unsigned long) new_fb;
1188 		info->flags = udlfb_info_flags;
1189 
1190 		/*
1191 		 * Second framebuffer copy to mirror the framebuffer state
1192 		 * on the physical USB device. We can function without this.
1193 		 * But with imperfect damage info we may send pixels over USB
1194 		 * that were, in fact, unchanged - wasting limited USB bandwidth
1195 		 */
1196 		if (shadow)
1197 			new_back = vzalloc(new_len);
1198 		if (!new_back)
1199 			dev_info(info->dev,
1200 				 "No shadow/backing buffer allocated\n");
1201 		else {
1202 			dlfb_deferred_vfree(dlfb, dlfb->backing_buffer);
1203 			dlfb->backing_buffer = new_back;
1204 		}
1205 	}
1206 	return 0;
1207 }
1208 
1209 /*
1210  * 1) Get EDID from hw, or use sw default
1211  * 2) Parse into various fb_info structs
1212  * 3) Allocate virtual framebuffer memory to back highest res mode
1213  *
1214  * Parses EDID into three places used by various parts of fbdev:
1215  * fb_var_screeninfo contains the timing of the monitor's preferred mode
1216  * fb_info.monspecs is full parsed EDID info, including monspecs.modedb
1217  * fb_info.modelist is a linked list of all monitor & VESA modes which work
1218  *
1219  * If EDID is not readable/valid, then modelist is all VESA modes,
1220  * monspecs is NULL, and fb_var_screeninfo is set to safe VESA mode
1221  * Returns 0 if successful
1222  */
1223 static int dlfb_setup_modes(struct dlfb_data *dlfb,
1224 			   struct fb_info *info,
1225 			   char *default_edid, size_t default_edid_size)
1226 {
1227 	char *edid;
1228 	int i, result = 0, tries = 3;
1229 	struct device *dev = info->device;
1230 	struct fb_videomode *mode;
1231 	const struct fb_videomode *default_vmode = NULL;
1232 
1233 	if (info->dev) {
1234 		/* only use mutex if info has been registered */
1235 		mutex_lock(&info->lock);
1236 		/* parent device is used otherwise */
1237 		dev = info->dev;
1238 	}
1239 
1240 	edid = kmalloc(EDID_LENGTH, GFP_KERNEL);
1241 	if (!edid) {
1242 		result = -ENOMEM;
1243 		goto error;
1244 	}
1245 
1246 	fb_destroy_modelist(&info->modelist);
1247 	memset(&info->monspecs, 0, sizeof(info->monspecs));
1248 
1249 	/*
1250 	 * Try to (re)read EDID from hardware first
1251 	 * EDID data may return, but not parse as valid
1252 	 * Try again a few times, in case of e.g. analog cable noise
1253 	 */
1254 	while (tries--) {
1255 
1256 		i = dlfb_get_edid(dlfb, edid, EDID_LENGTH);
1257 
1258 		if (i >= EDID_LENGTH)
1259 			fb_edid_to_monspecs(edid, &info->monspecs);
1260 
1261 		if (info->monspecs.modedb_len > 0) {
1262 			dlfb->edid = edid;
1263 			dlfb->edid_size = i;
1264 			break;
1265 		}
1266 	}
1267 
1268 	/* If that fails, use a previously returned EDID if available */
1269 	if (info->monspecs.modedb_len == 0) {
1270 		dev_err(dev, "Unable to get valid EDID from device/display\n");
1271 
1272 		if (dlfb->edid) {
1273 			fb_edid_to_monspecs(dlfb->edid, &info->monspecs);
1274 			if (info->monspecs.modedb_len > 0)
1275 				dev_err(dev, "Using previously queried EDID\n");
1276 		}
1277 	}
1278 
1279 	/* If that fails, use the default EDID we were handed */
1280 	if (info->monspecs.modedb_len == 0) {
1281 		if (default_edid_size >= EDID_LENGTH) {
1282 			fb_edid_to_monspecs(default_edid, &info->monspecs);
1283 			if (info->monspecs.modedb_len > 0) {
1284 				memcpy(edid, default_edid, default_edid_size);
1285 				dlfb->edid = edid;
1286 				dlfb->edid_size = default_edid_size;
1287 				dev_err(dev, "Using default/backup EDID\n");
1288 			}
1289 		}
1290 	}
1291 
1292 	/* If we've got modes, let's pick a best default mode */
1293 	if (info->monspecs.modedb_len > 0) {
1294 
1295 		for (i = 0; i < info->monspecs.modedb_len; i++) {
1296 			mode = &info->monspecs.modedb[i];
1297 			if (dlfb_is_valid_mode(mode, dlfb)) {
1298 				fb_add_videomode(mode, &info->modelist);
1299 			} else {
1300 				dev_dbg(dev, "Specified mode %dx%d too big\n",
1301 					mode->xres, mode->yres);
1302 				if (i == 0)
1303 					/* if we've removed top/best mode */
1304 					info->monspecs.misc
1305 						&= ~FB_MISC_1ST_DETAIL;
1306 			}
1307 		}
1308 
1309 		default_vmode = fb_find_best_display(&info->monspecs,
1310 						     &info->modelist);
1311 	}
1312 
1313 	/* If everything else has failed, fall back to safe default mode */
1314 	if (default_vmode == NULL) {
1315 
1316 		struct fb_videomode fb_vmode = {0};
1317 
1318 		/*
1319 		 * Add the standard VESA modes to our modelist
1320 		 * Since we don't have EDID, there may be modes that
1321 		 * overspec monitor and/or are incorrect aspect ratio, etc.
1322 		 * But at least the user has a chance to choose
1323 		 */
1324 		for (i = 0; i < VESA_MODEDB_SIZE; i++) {
1325 			mode = (struct fb_videomode *)&vesa_modes[i];
1326 			if (dlfb_is_valid_mode(mode, dlfb))
1327 				fb_add_videomode(mode, &info->modelist);
1328 			else
1329 				dev_dbg(dev, "VESA mode %dx%d too big\n",
1330 					mode->xres, mode->yres);
1331 		}
1332 
1333 		/*
1334 		 * default to resolution safe for projectors
1335 		 * (since they are most common case without EDID)
1336 		 */
1337 		fb_vmode.xres = 800;
1338 		fb_vmode.yres = 600;
1339 		fb_vmode.refresh = 60;
1340 		default_vmode = fb_find_nearest_mode(&fb_vmode,
1341 						     &info->modelist);
1342 	}
1343 
1344 	/* If we have good mode and no active clients*/
1345 	if ((default_vmode != NULL) && (dlfb->fb_count == 0)) {
1346 
1347 		fb_videomode_to_var(&info->var, default_vmode);
1348 		dlfb_var_color_format(&info->var);
1349 
1350 		/*
1351 		 * with mode size info, we can now alloc our framebuffer.
1352 		 */
1353 		memcpy(&info->fix, &dlfb_fix, sizeof(dlfb_fix));
1354 	} else
1355 		result = -EINVAL;
1356 
1357 error:
1358 	if (edid && (dlfb->edid != edid))
1359 		kfree(edid);
1360 
1361 	if (info->dev)
1362 		mutex_unlock(&info->lock);
1363 
1364 	return result;
1365 }
1366 
1367 static ssize_t metrics_bytes_rendered_show(struct device *fbdev,
1368 				   struct device_attribute *a, char *buf) {
1369 	struct fb_info *fb_info = dev_get_drvdata(fbdev);
1370 	struct dlfb_data *dlfb = fb_info->par;
1371 	return snprintf(buf, PAGE_SIZE, "%u\n",
1372 			atomic_read(&dlfb->bytes_rendered));
1373 }
1374 
1375 static ssize_t metrics_bytes_identical_show(struct device *fbdev,
1376 				   struct device_attribute *a, char *buf) {
1377 	struct fb_info *fb_info = dev_get_drvdata(fbdev);
1378 	struct dlfb_data *dlfb = fb_info->par;
1379 	return snprintf(buf, PAGE_SIZE, "%u\n",
1380 			atomic_read(&dlfb->bytes_identical));
1381 }
1382 
1383 static ssize_t metrics_bytes_sent_show(struct device *fbdev,
1384 				   struct device_attribute *a, char *buf) {
1385 	struct fb_info *fb_info = dev_get_drvdata(fbdev);
1386 	struct dlfb_data *dlfb = fb_info->par;
1387 	return snprintf(buf, PAGE_SIZE, "%u\n",
1388 			atomic_read(&dlfb->bytes_sent));
1389 }
1390 
1391 static ssize_t metrics_cpu_kcycles_used_show(struct device *fbdev,
1392 				   struct device_attribute *a, char *buf) {
1393 	struct fb_info *fb_info = dev_get_drvdata(fbdev);
1394 	struct dlfb_data *dlfb = fb_info->par;
1395 	return snprintf(buf, PAGE_SIZE, "%u\n",
1396 			atomic_read(&dlfb->cpu_kcycles_used));
1397 }
1398 
1399 static ssize_t edid_show(
1400 			struct file *filp,
1401 			struct kobject *kobj, struct bin_attribute *a,
1402 			 char *buf, loff_t off, size_t count) {
1403 	struct device *fbdev = container_of(kobj, struct device, kobj);
1404 	struct fb_info *fb_info = dev_get_drvdata(fbdev);
1405 	struct dlfb_data *dlfb = fb_info->par;
1406 
1407 	if (dlfb->edid == NULL)
1408 		return 0;
1409 
1410 	if ((off >= dlfb->edid_size) || (count > dlfb->edid_size))
1411 		return 0;
1412 
1413 	if (off + count > dlfb->edid_size)
1414 		count = dlfb->edid_size - off;
1415 
1416 	memcpy(buf, dlfb->edid, count);
1417 
1418 	return count;
1419 }
1420 
1421 static ssize_t edid_store(
1422 			struct file *filp,
1423 			struct kobject *kobj, struct bin_attribute *a,
1424 			char *src, loff_t src_off, size_t src_size) {
1425 	struct device *fbdev = container_of(kobj, struct device, kobj);
1426 	struct fb_info *fb_info = dev_get_drvdata(fbdev);
1427 	struct dlfb_data *dlfb = fb_info->par;
1428 	int ret;
1429 
1430 	/* We only support write of entire EDID at once, no offset*/
1431 	if ((src_size != EDID_LENGTH) || (src_off != 0))
1432 		return -EINVAL;
1433 
1434 	ret = dlfb_setup_modes(dlfb, fb_info, src, src_size);
1435 	if (ret)
1436 		return ret;
1437 
1438 	if (!dlfb->edid || memcmp(src, dlfb->edid, src_size))
1439 		return -EINVAL;
1440 
1441 	ret = dlfb_ops_set_par(fb_info);
1442 	if (ret)
1443 		return ret;
1444 
1445 	return src_size;
1446 }
1447 
1448 static ssize_t metrics_reset_store(struct device *fbdev,
1449 			   struct device_attribute *attr,
1450 			   const char *buf, size_t count)
1451 {
1452 	struct fb_info *fb_info = dev_get_drvdata(fbdev);
1453 	struct dlfb_data *dlfb = fb_info->par;
1454 
1455 	atomic_set(&dlfb->bytes_rendered, 0);
1456 	atomic_set(&dlfb->bytes_identical, 0);
1457 	atomic_set(&dlfb->bytes_sent, 0);
1458 	atomic_set(&dlfb->cpu_kcycles_used, 0);
1459 
1460 	return count;
1461 }
1462 
1463 static const struct bin_attribute edid_attr = {
1464 	.attr.name = "edid",
1465 	.attr.mode = 0666,
1466 	.size = EDID_LENGTH,
1467 	.read = edid_show,
1468 	.write = edid_store
1469 };
1470 
1471 static const struct device_attribute fb_device_attrs[] = {
1472 	__ATTR_RO(metrics_bytes_rendered),
1473 	__ATTR_RO(metrics_bytes_identical),
1474 	__ATTR_RO(metrics_bytes_sent),
1475 	__ATTR_RO(metrics_cpu_kcycles_used),
1476 	__ATTR(metrics_reset, S_IWUSR, NULL, metrics_reset_store),
1477 };
1478 
1479 /*
1480  * This is necessary before we can communicate with the display controller.
1481  */
1482 static int dlfb_select_std_channel(struct dlfb_data *dlfb)
1483 {
1484 	int ret;
1485 	void *buf;
1486 	static const u8 set_def_chn[] = {
1487 				0x57, 0xCD, 0xDC, 0xA7,
1488 				0x1C, 0x88, 0x5E, 0x15,
1489 				0x60, 0xFE, 0xC6, 0x97,
1490 				0x16, 0x3D, 0x47, 0xF2  };
1491 
1492 	buf = kmemdup(set_def_chn, sizeof(set_def_chn), GFP_KERNEL);
1493 
1494 	if (!buf)
1495 		return -ENOMEM;
1496 
1497 	ret = usb_control_msg(dlfb->udev, usb_sndctrlpipe(dlfb->udev, 0),
1498 			NR_USB_REQUEST_CHANNEL,
1499 			(USB_DIR_OUT | USB_TYPE_VENDOR), 0, 0,
1500 			buf, sizeof(set_def_chn), USB_CTRL_SET_TIMEOUT);
1501 
1502 	kfree(buf);
1503 
1504 	return ret;
1505 }
1506 
1507 static int dlfb_parse_vendor_descriptor(struct dlfb_data *dlfb,
1508 					struct usb_interface *intf)
1509 {
1510 	char *desc;
1511 	char *buf;
1512 	char *desc_end;
1513 	int total_len;
1514 
1515 	buf = kzalloc(MAX_VENDOR_DESCRIPTOR_SIZE, GFP_KERNEL);
1516 	if (!buf)
1517 		return false;
1518 	desc = buf;
1519 
1520 	total_len = usb_get_descriptor(interface_to_usbdev(intf),
1521 					0x5f, /* vendor specific */
1522 					0, desc, MAX_VENDOR_DESCRIPTOR_SIZE);
1523 
1524 	/* if not found, look in configuration descriptor */
1525 	if (total_len < 0) {
1526 		if (0 == usb_get_extra_descriptor(intf->cur_altsetting,
1527 			0x5f, &desc))
1528 			total_len = (int) desc[0];
1529 	}
1530 
1531 	if (total_len > 5) {
1532 		dev_info(&intf->dev,
1533 			 "vendor descriptor length: %d data: %11ph\n",
1534 			 total_len, desc);
1535 
1536 		if ((desc[0] != total_len) || /* descriptor length */
1537 		    (desc[1] != 0x5f) ||   /* vendor descriptor type */
1538 		    (desc[2] != 0x01) ||   /* version (2 bytes) */
1539 		    (desc[3] != 0x00) ||
1540 		    (desc[4] != total_len - 2)) /* length after type */
1541 			goto unrecognized;
1542 
1543 		desc_end = desc + total_len;
1544 		desc += 5; /* the fixed header we've already parsed */
1545 
1546 		while (desc < desc_end) {
1547 			u8 length;
1548 			u16 key;
1549 
1550 			key = *desc++;
1551 			key |= (u16)*desc++ << 8;
1552 			length = *desc++;
1553 
1554 			switch (key) {
1555 			case 0x0200: { /* max_area */
1556 				u32 max_area = *desc++;
1557 				max_area |= (u32)*desc++ << 8;
1558 				max_area |= (u32)*desc++ << 16;
1559 				max_area |= (u32)*desc++ << 24;
1560 				dev_warn(&intf->dev,
1561 					 "DL chip limited to %d pixel modes\n",
1562 					 max_area);
1563 				dlfb->sku_pixel_limit = max_area;
1564 				break;
1565 			}
1566 			default:
1567 				break;
1568 			}
1569 			desc += length;
1570 		}
1571 	} else {
1572 		dev_info(&intf->dev, "vendor descriptor not available (%d)\n",
1573 			 total_len);
1574 	}
1575 
1576 	goto success;
1577 
1578 unrecognized:
1579 	/* allow udlfb to load for now even if firmware unrecognized */
1580 	dev_err(&intf->dev, "Unrecognized vendor firmware descriptor\n");
1581 
1582 success:
1583 	kfree(buf);
1584 	return true;
1585 }
1586 
1587 static int dlfb_usb_probe(struct usb_interface *intf,
1588 			  const struct usb_device_id *id)
1589 {
1590 	int i;
1591 	const struct device_attribute *attr;
1592 	struct dlfb_data *dlfb;
1593 	struct fb_info *info;
1594 	int retval = -ENOMEM;
1595 	struct usb_device *usbdev = interface_to_usbdev(intf);
1596 
1597 	/* usb initialization */
1598 	dlfb = kzalloc(sizeof(*dlfb), GFP_KERNEL);
1599 	if (!dlfb) {
1600 		dev_err(&intf->dev, "%s: failed to allocate dlfb\n", __func__);
1601 		return -ENOMEM;
1602 	}
1603 
1604 	INIT_LIST_HEAD(&dlfb->deferred_free);
1605 
1606 	dlfb->udev = usb_get_dev(usbdev);
1607 	usb_set_intfdata(intf, dlfb);
1608 
1609 	dev_dbg(&intf->dev, "console enable=%d\n", console);
1610 	dev_dbg(&intf->dev, "fb_defio enable=%d\n", fb_defio);
1611 	dev_dbg(&intf->dev, "shadow enable=%d\n", shadow);
1612 
1613 	dlfb->sku_pixel_limit = 2048 * 1152; /* default to maximum */
1614 
1615 	if (!dlfb_parse_vendor_descriptor(dlfb, intf)) {
1616 		dev_err(&intf->dev,
1617 			"firmware not recognized, incompatible device?\n");
1618 		goto error;
1619 	}
1620 
1621 	if (pixel_limit) {
1622 		dev_warn(&intf->dev,
1623 			 "DL chip limit of %d overridden to %d\n",
1624 			 dlfb->sku_pixel_limit, pixel_limit);
1625 		dlfb->sku_pixel_limit = pixel_limit;
1626 	}
1627 
1628 
1629 	/* allocates framebuffer driver structure, not framebuffer memory */
1630 	info = framebuffer_alloc(0, &dlfb->udev->dev);
1631 	if (!info) {
1632 		dev_err(&dlfb->udev->dev, "framebuffer_alloc failed\n");
1633 		goto error;
1634 	}
1635 
1636 	dlfb->info = info;
1637 	info->par = dlfb;
1638 	info->pseudo_palette = dlfb->pseudo_palette;
1639 	dlfb->ops = dlfb_ops;
1640 	info->fbops = &dlfb->ops;
1641 
1642 	INIT_LIST_HEAD(&info->modelist);
1643 
1644 	if (!dlfb_alloc_urb_list(dlfb, WRITES_IN_FLIGHT, MAX_TRANSFER)) {
1645 		retval = -ENOMEM;
1646 		dev_err(&intf->dev, "unable to allocate urb list\n");
1647 		goto error;
1648 	}
1649 
1650 	/* We don't register a new USB class. Our client interface is dlfbev */
1651 
1652 	retval = fb_alloc_cmap(&info->cmap, 256, 0);
1653 	if (retval < 0) {
1654 		dev_err(info->device, "cmap allocation failed: %d\n", retval);
1655 		goto error;
1656 	}
1657 
1658 	retval = dlfb_setup_modes(dlfb, info, NULL, 0);
1659 	if (retval != 0) {
1660 		dev_err(info->device,
1661 			"unable to find common mode for display and adapter\n");
1662 		goto error;
1663 	}
1664 
1665 	/* ready to begin using device */
1666 
1667 	atomic_set(&dlfb->usb_active, 1);
1668 	dlfb_select_std_channel(dlfb);
1669 
1670 	dlfb_ops_check_var(&info->var, info);
1671 	retval = dlfb_ops_set_par(info);
1672 	if (retval)
1673 		goto error;
1674 
1675 	retval = register_framebuffer(info);
1676 	if (retval < 0) {
1677 		dev_err(info->device, "unable to register framebuffer: %d\n",
1678 			retval);
1679 		goto error;
1680 	}
1681 
1682 	for (i = 0; i < ARRAY_SIZE(fb_device_attrs); i++) {
1683 		attr = &fb_device_attrs[i];
1684 		retval = device_create_file(info->dev, attr);
1685 		if (retval)
1686 			dev_warn(info->device,
1687 				 "failed to create '%s' attribute: %d\n",
1688 				 attr->attr.name, retval);
1689 	}
1690 
1691 	retval = device_create_bin_file(info->dev, &edid_attr);
1692 	if (retval)
1693 		dev_warn(info->device, "failed to create '%s' attribute: %d\n",
1694 			 edid_attr.attr.name, retval);
1695 
1696 	dev_info(info->device,
1697 		 "%s is DisplayLink USB device (%dx%d, %dK framebuffer memory)\n",
1698 		 dev_name(info->dev), info->var.xres, info->var.yres,
1699 		 ((dlfb->backing_buffer) ?
1700 		 info->fix.smem_len * 2 : info->fix.smem_len) >> 10);
1701 	return 0;
1702 
1703 error:
1704 	if (dlfb->info) {
1705 		dlfb_ops_destroy(dlfb->info);
1706 	} else {
1707 		usb_put_dev(dlfb->udev);
1708 		kfree(dlfb);
1709 	}
1710 	return retval;
1711 }
1712 
1713 static void dlfb_usb_disconnect(struct usb_interface *intf)
1714 {
1715 	struct dlfb_data *dlfb;
1716 	struct fb_info *info;
1717 	int i;
1718 
1719 	dlfb = usb_get_intfdata(intf);
1720 	info = dlfb->info;
1721 
1722 	dev_dbg(&intf->dev, "USB disconnect starting\n");
1723 
1724 	/* we virtualize until all fb clients release. Then we free */
1725 	dlfb->virtualized = true;
1726 
1727 	/* When non-active we'll update virtual framebuffer, but no new urbs */
1728 	atomic_set(&dlfb->usb_active, 0);
1729 
1730 	/* this function will wait for all in-flight urbs to complete */
1731 	dlfb_free_urb_list(dlfb);
1732 
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 
1738 	unregister_framebuffer(info);
1739 }
1740 
1741 static struct usb_driver dlfb_driver = {
1742 	.name = "udlfb",
1743 	.probe = dlfb_usb_probe,
1744 	.disconnect = dlfb_usb_disconnect,
1745 	.id_table = id_table,
1746 };
1747 
1748 module_usb_driver(dlfb_driver);
1749 
1750 static void dlfb_urb_completion(struct urb *urb)
1751 {
1752 	struct urb_node *unode = urb->context;
1753 	struct dlfb_data *dlfb = unode->dlfb;
1754 	unsigned long flags;
1755 
1756 	switch (urb->status) {
1757 	case 0:
1758 		/* success */
1759 		break;
1760 	case -ECONNRESET:
1761 	case -ENOENT:
1762 	case -ESHUTDOWN:
1763 		/* sync/async unlink faults aren't errors */
1764 		break;
1765 	default:
1766 		dev_err(&dlfb->udev->dev,
1767 			"%s - nonzero write bulk status received: %d\n",
1768 			__func__, urb->status);
1769 		atomic_set(&dlfb->lost_pixels, 1);
1770 		break;
1771 	}
1772 
1773 	urb->transfer_buffer_length = dlfb->urbs.size; /* reset to actual */
1774 
1775 	spin_lock_irqsave(&dlfb->urbs.lock, flags);
1776 	list_add_tail(&unode->entry, &dlfb->urbs.list);
1777 	dlfb->urbs.available++;
1778 	spin_unlock_irqrestore(&dlfb->urbs.lock, flags);
1779 
1780 	up(&dlfb->urbs.limit_sem);
1781 }
1782 
1783 static void dlfb_free_urb_list(struct dlfb_data *dlfb)
1784 {
1785 	int count = dlfb->urbs.count;
1786 	struct list_head *node;
1787 	struct urb_node *unode;
1788 	struct urb *urb;
1789 
1790 	/* keep waiting and freeing, until we've got 'em all */
1791 	while (count--) {
1792 		down(&dlfb->urbs.limit_sem);
1793 
1794 		spin_lock_irq(&dlfb->urbs.lock);
1795 
1796 		node = dlfb->urbs.list.next; /* have reserved one with sem */
1797 		list_del_init(node);
1798 
1799 		spin_unlock_irq(&dlfb->urbs.lock);
1800 
1801 		unode = list_entry(node, struct urb_node, entry);
1802 		urb = unode->urb;
1803 
1804 		/* Free each separately allocated piece */
1805 		usb_free_coherent(urb->dev, dlfb->urbs.size,
1806 				  urb->transfer_buffer, urb->transfer_dma);
1807 		usb_free_urb(urb);
1808 		kfree(node);
1809 	}
1810 
1811 	dlfb->urbs.count = 0;
1812 }
1813 
1814 static int dlfb_alloc_urb_list(struct dlfb_data *dlfb, int count, size_t size)
1815 {
1816 	struct urb *urb;
1817 	struct urb_node *unode;
1818 	char *buf;
1819 	size_t wanted_size = count * size;
1820 
1821 	spin_lock_init(&dlfb->urbs.lock);
1822 
1823 retry:
1824 	dlfb->urbs.size = size;
1825 	INIT_LIST_HEAD(&dlfb->urbs.list);
1826 
1827 	sema_init(&dlfb->urbs.limit_sem, 0);
1828 	dlfb->urbs.count = 0;
1829 	dlfb->urbs.available = 0;
1830 
1831 	while (dlfb->urbs.count * size < wanted_size) {
1832 		unode = kzalloc(sizeof(*unode), GFP_KERNEL);
1833 		if (!unode)
1834 			break;
1835 		unode->dlfb = dlfb;
1836 
1837 		urb = usb_alloc_urb(0, GFP_KERNEL);
1838 		if (!urb) {
1839 			kfree(unode);
1840 			break;
1841 		}
1842 		unode->urb = urb;
1843 
1844 		buf = usb_alloc_coherent(dlfb->udev, size, GFP_KERNEL,
1845 					 &urb->transfer_dma);
1846 		if (!buf) {
1847 			kfree(unode);
1848 			usb_free_urb(urb);
1849 			if (size > PAGE_SIZE) {
1850 				size /= 2;
1851 				dlfb_free_urb_list(dlfb);
1852 				goto retry;
1853 			}
1854 			break;
1855 		}
1856 
1857 		/* urb->transfer_buffer_length set to actual before submit */
1858 		usb_fill_bulk_urb(urb, dlfb->udev, usb_sndbulkpipe(dlfb->udev, 1),
1859 			buf, size, dlfb_urb_completion, unode);
1860 		urb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;
1861 
1862 		list_add_tail(&unode->entry, &dlfb->urbs.list);
1863 
1864 		up(&dlfb->urbs.limit_sem);
1865 		dlfb->urbs.count++;
1866 		dlfb->urbs.available++;
1867 	}
1868 
1869 	return dlfb->urbs.count;
1870 }
1871 
1872 static struct urb *dlfb_get_urb(struct dlfb_data *dlfb)
1873 {
1874 	int ret;
1875 	struct list_head *entry;
1876 	struct urb_node *unode;
1877 
1878 	/* Wait for an in-flight buffer to complete and get re-queued */
1879 	ret = down_timeout(&dlfb->urbs.limit_sem, GET_URB_TIMEOUT);
1880 	if (ret) {
1881 		atomic_set(&dlfb->lost_pixels, 1);
1882 		dev_warn(&dlfb->udev->dev,
1883 			 "wait for urb interrupted: %d available: %d\n",
1884 			 ret, dlfb->urbs.available);
1885 		return NULL;
1886 	}
1887 
1888 	spin_lock_irq(&dlfb->urbs.lock);
1889 
1890 	BUG_ON(list_empty(&dlfb->urbs.list)); /* reserved one with limit_sem */
1891 	entry = dlfb->urbs.list.next;
1892 	list_del_init(entry);
1893 	dlfb->urbs.available--;
1894 
1895 	spin_unlock_irq(&dlfb->urbs.lock);
1896 
1897 	unode = list_entry(entry, struct urb_node, entry);
1898 	return unode->urb;
1899 }
1900 
1901 static int dlfb_submit_urb(struct dlfb_data *dlfb, struct urb *urb, size_t len)
1902 {
1903 	int ret;
1904 
1905 	BUG_ON(len > dlfb->urbs.size);
1906 
1907 	urb->transfer_buffer_length = len; /* set to actual payload len */
1908 	ret = usb_submit_urb(urb, GFP_KERNEL);
1909 	if (ret) {
1910 		dlfb_urb_completion(urb); /* because no one else will */
1911 		atomic_set(&dlfb->lost_pixels, 1);
1912 		dev_err(&dlfb->udev->dev, "submit urb error: %d\n", ret);
1913 	}
1914 	return ret;
1915 }
1916 
1917 module_param(console, bool, S_IWUSR | S_IRUSR | S_IWGRP | S_IRGRP);
1918 MODULE_PARM_DESC(console, "Allow fbcon to open framebuffer");
1919 
1920 module_param(fb_defio, bool, S_IWUSR | S_IRUSR | S_IWGRP | S_IRGRP);
1921 MODULE_PARM_DESC(fb_defio, "Page fault detection of mmap writes");
1922 
1923 module_param(shadow, bool, S_IWUSR | S_IRUSR | S_IWGRP | S_IRGRP);
1924 MODULE_PARM_DESC(shadow, "Shadow vid mem. Disable to save mem but lose perf");
1925 
1926 module_param(pixel_limit, int, S_IWUSR | S_IRUSR | S_IWGRP | S_IRGRP);
1927 MODULE_PARM_DESC(pixel_limit, "Force limit on max mode (in x*y pixels)");
1928 
1929 MODULE_AUTHOR("Roberto De Ioris <roberto@unbit.it>, "
1930 	      "Jaya Kumar <jayakumar.lkml@gmail.com>, "
1931 	      "Bernie Thompson <bernie@plugable.com>");
1932 MODULE_DESCRIPTION("DisplayLink kernel framebuffer driver");
1933 MODULE_LICENSE("GPL");
1934 
1935