udlfb.c

   1// SPDX-License-Identifier: GPL-2.0-only
   2/*
   3 * udlfb.c -- Framebuffer driver for DisplayLink USB controller
   4 *
   5 * Copyright (C) 2009 Roberto De Ioris <roberto@unbit.it>
   6 * Copyright (C) 2009 Jaya Kumar <jayakumar.lkml@gmail.com>
   7 * Copyright (C) 2009 Bernie Thompson <bernie@plugable.com>
   8 *
   9 * Layout is based on skeletonfb by James Simmons and Geert Uytterhoeven,
  10 * usb-skeleton by GregKH.
  11 *
  12 * Device-specific portions based on information from Displaylink, with work
  13 * from Florian Echtler, Henrik Bjerregaard Pedersen, and others.
  14 */
  15
  16#include <linux/module.h>
  17#include <linux/kernel.h>
  18#include <linux/init.h>
  19#include <linux/usb.h>
  20#include <linux/uaccess.h>
  21#include <linux/mm.h>
  22#include <linux/fb.h>
  23#include <linux/vmalloc.h>
  24#include <linux/slab.h>
  25#include <linux/delay.h>
  26#include <linux/unaligned.h>
  27#include <video/udlfb.h>
  28#include "edid.h"
  29
  30#define OUT_EP_NUM	1	/* The endpoint number we will use */
  31
  32static const struct fb_fix_screeninfo dlfb_fix = {
  33	.id =           "udlfb",
  34	.type =         FB_TYPE_PACKED_PIXELS,
  35	.visual =       FB_VISUAL_TRUECOLOR,
  36	.xpanstep =     0,
  37	.ypanstep =     0,
  38	.ywrapstep =    0,
  39	.accel =        FB_ACCEL_NONE,
  40};
  41
  42static const u32 udlfb_info_flags = FBINFO_READS_FAST |
  43		FBINFO_VIRTFB |
  44		FBINFO_HWACCEL_IMAGEBLIT | FBINFO_HWACCEL_FILLRECT |
  45		FBINFO_HWACCEL_COPYAREA | FBINFO_MISC_ALWAYS_SETPAR;
  46
  47/*
  48 * There are many DisplayLink-based graphics products, all with unique PIDs.
  49 * So we match on DisplayLink's VID + Vendor-Defined Interface Class (0xff)
  50 * We also require a match on SubClass (0x00) and Protocol (0x00),
  51 * which is compatible with all known USB 2.0 era graphics chips and firmware,
  52 * but allows DisplayLink to increment those for any future incompatible chips
  53 */
  54static const struct usb_device_id id_table[] = {
  55	{.idVendor = 0x17e9,
  56	 .bInterfaceClass = 0xff,
  57	 .bInterfaceSubClass = 0x00,
  58	 .bInterfaceProtocol = 0x00,
  59	 .match_flags = USB_DEVICE_ID_MATCH_VENDOR |
  60		USB_DEVICE_ID_MATCH_INT_CLASS |
  61		USB_DEVICE_ID_MATCH_INT_SUBCLASS |
  62		USB_DEVICE_ID_MATCH_INT_PROTOCOL,
  63	},
  64	{},
  65};
  66MODULE_DEVICE_TABLE(usb, id_table);
  67
  68/* module options */
  69static bool console = true; /* Allow fbcon to open framebuffer */
  70static bool fb_defio = true;  /* Detect mmap writes using page faults */
  71static bool shadow = true; /* Optionally disable shadow framebuffer */
  72static int pixel_limit; /* Optionally force a pixel resolution limit */
  73
  74struct dlfb_deferred_free {
  75	struct list_head list;
  76	void *mem;
  77};
  78
  79static int dlfb_realloc_framebuffer(struct dlfb_data *dlfb, struct fb_info *info, u32 new_len);
  80
  81/* dlfb keeps a list of urbs for efficient bulk transfers */
  82static void dlfb_urb_completion(struct urb *urb);
  83static struct urb *dlfb_get_urb(struct dlfb_data *dlfb);
  84static int dlfb_submit_urb(struct dlfb_data *dlfb, struct urb * urb, size_t len);
  85static int dlfb_alloc_urb_list(struct dlfb_data *dlfb, int count, size_t size);
  86static void dlfb_free_urb_list(struct dlfb_data *dlfb);
  87
  88/*
  89 * All DisplayLink bulk operations start with 0xAF, followed by specific code
  90 * All operations are written to buffers which then later get sent to device
  91 */
  92static char *dlfb_set_register(char *buf, u8 reg, u8 val)
  93{
  94	*buf++ = 0xAF;
  95	*buf++ = 0x20;
  96	*buf++ = reg;
  97	*buf++ = val;
  98	return buf;
  99}
 100
 101static char *dlfb_vidreg_lock(char *buf)
 102{
 103	return dlfb_set_register(buf, 0xFF, 0x00);
 104}
 105
 106static char *dlfb_vidreg_unlock(char *buf)
 107{
 108	return dlfb_set_register(buf, 0xFF, 0xFF);
 109}
 110
 111/*
 112 * Map FB_BLANK_* to DisplayLink register
 113 * DLReg FB_BLANK_*
 114 * ----- -----------------------------
 115 *  0x00 FB_BLANK_UNBLANK (0)
 116 *  0x01 FB_BLANK (1)
 117 *  0x03 FB_BLANK_VSYNC_SUSPEND (2)
 118 *  0x05 FB_BLANK_HSYNC_SUSPEND (3)
 119 *  0x07 FB_BLANK_POWERDOWN (4) Note: requires modeset to come back
 120 */
 121static char *dlfb_blanking(char *buf, int fb_blank)
 122{
 123	u8 reg;
 124
 125	switch (fb_blank) {
 126	case FB_BLANK_POWERDOWN:
 127		reg = 0x07;
 128		break;
 129	case FB_BLANK_HSYNC_SUSPEND:
 130		reg = 0x05;
 131		break;
 132	case FB_BLANK_VSYNC_SUSPEND:
 133		reg = 0x03;
 134		break;
 135	case FB_BLANK_NORMAL:
 136		reg = 0x01;
 137		break;
 138	default:
 139		reg = 0x00;
 140	}
 141
 142	buf = dlfb_set_register(buf, 0x1F, reg);
 143
 144	return buf;
 145}
 146
 147static char *dlfb_set_color_depth(char *buf, u8 selection)
 148{
 149	return dlfb_set_register(buf, 0x00, selection);
 150}
 151
 152static char *dlfb_set_base16bpp(char *wrptr, u32 base)
 153{
 154	/* the base pointer is 16 bits wide, 0x20 is hi byte. */
 155	wrptr = dlfb_set_register(wrptr, 0x20, base >> 16);
 156	wrptr = dlfb_set_register(wrptr, 0x21, base >> 8);
 157	return dlfb_set_register(wrptr, 0x22, base);
 158}
 159
 160/*
 161 * DisplayLink HW has separate 16bpp and 8bpp framebuffers.
 162 * In 24bpp modes, the low 323 RGB bits go in the 8bpp framebuffer
 163 */
 164static char *dlfb_set_base8bpp(char *wrptr, u32 base)
 165{
 166	wrptr = dlfb_set_register(wrptr, 0x26, base >> 16);
 167	wrptr = dlfb_set_register(wrptr, 0x27, base >> 8);
 168	return dlfb_set_register(wrptr, 0x28, base);
 169}
 170
 171static char *dlfb_set_register_16(char *wrptr, u8 reg, u16 value)
 172{
 173	wrptr = dlfb_set_register(wrptr, reg, value >> 8);
 174	return dlfb_set_register(wrptr, reg+1, value);
 175}
 176
 177/*
 178 * This is kind of weird because the controller takes some
 179 * register values in a different byte order than other registers.
 180 */
 181static char *dlfb_set_register_16be(char *wrptr, u8 reg, u16 value)
 182{
 183	wrptr = dlfb_set_register(wrptr, reg, value);
 184	return dlfb_set_register(wrptr, reg+1, value >> 8);
 185}
 186
 187/*
 188 * LFSR is linear feedback shift register. The reason we have this is
 189 * because the display controller needs to minimize the clock depth of
 190 * various counters used in the display path. So this code reverses the
 191 * provided value into the lfsr16 value by counting backwards to get
 192 * the value that needs to be set in the hardware comparator to get the
 193 * same actual count. This makes sense once you read above a couple of
 194 * times and think about it from a hardware perspective.
 195 */
 196static u16 dlfb_lfsr16(u16 actual_count)
 197{
 198	u32 lv = 0xFFFF; /* This is the lfsr value that the hw starts with */
 199
 200	while (actual_count--) {
 201		lv =	 ((lv << 1) |
 202			(((lv >> 15) ^ (lv >> 4) ^ (lv >> 2) ^ (lv >> 1)) & 1))
 203			& 0xFFFF;
 204	}
 205
 206	return (u16) lv;
 207}
 208
 209/*
 210 * This does LFSR conversion on the value that is to be written.
 211 * See LFSR explanation above for more detail.
 212 */
 213static char *dlfb_set_register_lfsr16(char *wrptr, u8 reg, u16 value)
 214{
 215	return dlfb_set_register_16(wrptr, reg, dlfb_lfsr16(value));
 216}
 217
 218/*
 219 * This takes a standard fbdev screeninfo struct and all of its monitor mode
 220 * details and converts them into the DisplayLink equivalent register commands.
 221 */
 222static char *dlfb_set_vid_cmds(char *wrptr, struct fb_var_screeninfo *var)
 223{
 224	u16 xds, yds;
 225	u16 xde, yde;
 226	u16 yec;
 227
 228	/* x display start */
 229	xds = var->left_margin + var->hsync_len;
 230	wrptr = dlfb_set_register_lfsr16(wrptr, 0x01, xds);
 231	/* x display end */
 232	xde = xds + var->xres;
 233	wrptr = dlfb_set_register_lfsr16(wrptr, 0x03, xde);
 234
 235	/* y display start */
 236	yds = var->upper_margin + var->vsync_len;
 237	wrptr = dlfb_set_register_lfsr16(wrptr, 0x05, yds);
 238	/* y display end */
 239	yde = yds + var->yres;
 240	wrptr = dlfb_set_register_lfsr16(wrptr, 0x07, yde);
 241
 242	/* x end count is active + blanking - 1 */
 243	wrptr = dlfb_set_register_lfsr16(wrptr, 0x09,
 244			xde + var->right_margin - 1);
 245
 246	/* libdlo hardcodes hsync start to 1 */
 247	wrptr = dlfb_set_register_lfsr16(wrptr, 0x0B, 1);
 248
 249	/* hsync end is width of sync pulse + 1 */
 250	wrptr = dlfb_set_register_lfsr16(wrptr, 0x0D, var->hsync_len + 1);
 251
 252	/* hpixels is active pixels */
 253	wrptr = dlfb_set_register_16(wrptr, 0x0F, var->xres);
 254
 255	/* yendcount is vertical active + vertical blanking */
 256	yec = var->yres + var->upper_margin + var->lower_margin +
 257			var->vsync_len;
 258	wrptr = dlfb_set_register_lfsr16(wrptr, 0x11, yec);
 259
 260	/* libdlo hardcodes vsync start to 0 */
 261	wrptr = dlfb_set_register_lfsr16(wrptr, 0x13, 0);
 262
 263	/* vsync end is width of vsync pulse */
 264	wrptr = dlfb_set_register_lfsr16(wrptr, 0x15, var->vsync_len);
 265
 266	/* vpixels is active pixels */
 267	wrptr = dlfb_set_register_16(wrptr, 0x17, var->yres);
 268
 269	/* convert picoseconds to 5kHz multiple for pclk5k = x * 1E12/5k */
 270	wrptr = dlfb_set_register_16be(wrptr, 0x1B,
 271			200*1000*1000/var->pixclock);
 272
 273	return wrptr;
 274}
 275
 276/*
 277 * This takes a standard fbdev screeninfo struct that was fetched or prepared
 278 * and then generates the appropriate command sequence that then drives the
 279 * display controller.
 280 */
 281static int dlfb_set_video_mode(struct dlfb_data *dlfb,
 282				struct fb_var_screeninfo *var)
 283{
 284	char *buf;
 285	char *wrptr;
 286	int retval;
 287	int writesize;
 288	struct urb *urb;
 289
 290	if (!atomic_read(&dlfb->usb_active))
 291		return -EPERM;
 292
 293	urb = dlfb_get_urb(dlfb);
 294	if (!urb)
 295		return -ENOMEM;
 296
 297	buf = (char *) urb->transfer_buffer;
 298
 299	/*
 300	* This first section has to do with setting the base address on the
 301	* controller * associated with the display. There are 2 base
 302	* pointers, currently, we only * use the 16 bpp segment.
 303	*/
 304	wrptr = dlfb_vidreg_lock(buf);
 305	wrptr = dlfb_set_color_depth(wrptr, 0x00);
 306	/* set base for 16bpp segment to 0 */
 307	wrptr = dlfb_set_base16bpp(wrptr, 0);
 308	/* set base for 8bpp segment to end of fb */
 309	wrptr = dlfb_set_base8bpp(wrptr, dlfb->info->fix.smem_len);
 310
 311	wrptr = dlfb_set_vid_cmds(wrptr, var);
 312	wrptr = dlfb_blanking(wrptr, FB_BLANK_UNBLANK);
 313	wrptr = dlfb_vidreg_unlock(wrptr);
 314
 315	writesize = wrptr - buf;
 316
 317	retval = dlfb_submit_urb(dlfb, urb, writesize);
 318
 319	dlfb->blank_mode = FB_BLANK_UNBLANK;
 320
 321	return retval;
 322}
 323
 324static int dlfb_ops_mmap(struct fb_info *info, struct vm_area_struct *vma)
 325{
 326	unsigned long start = vma->vm_start;
 327	unsigned long size = vma->vm_end - vma->vm_start;
 328	unsigned long offset = vma->vm_pgoff << PAGE_SHIFT;
 329	unsigned long page, pos;
 330
 331	if (info->fbdefio)
 332		return fb_deferred_io_mmap(info, vma);
 333
 334	vma->vm_page_prot = pgprot_decrypted(vma->vm_page_prot);
 335
 336	if (vma->vm_pgoff > (~0UL >> PAGE_SHIFT))
 337		return -EINVAL;
 338	if (size > info->fix.smem_len)
 339		return -EINVAL;
 340	if (offset > info->fix.smem_len - size)
 341		return -EINVAL;
 342
 343	pos = (unsigned long)info->fix.smem_start + offset;
 344
 345	dev_dbg(info->dev, "mmap() framebuffer addr:%lu size:%lu\n",
 346		pos, size);
 347
 348	while (size > 0) {
 349		page = vmalloc_to_pfn((void *)pos);
 350		if (remap_pfn_range(vma, start, page, PAGE_SIZE, PAGE_SHARED))
 351			return -EAGAIN;
 352
 353		start += PAGE_SIZE;
 354		pos += PAGE_SIZE;
 355		if (size > PAGE_SIZE)
 356			size -= PAGE_SIZE;
 357		else
 358			size = 0;
 359	}
 360
 361	return 0;
 362}
 363
 364/*
 365 * Trims identical data from front and back of line
 366 * Sets new front buffer address and width
 367 * And returns byte count of identical pixels
 368 * Assumes CPU natural alignment (unsigned long)
 369 * for back and front buffer ptrs and width
 370 */
 371static int dlfb_trim_hline(const u8 *bback, const u8 **bfront, int *width_bytes)
 372{
 373	int j, k;
 374	const unsigned long *back = (const unsigned long *) bback;
 375	const unsigned long *front = (const unsigned long *) *bfront;
 376	const int width = *width_bytes / sizeof(unsigned long);
 377	int identical;
 378	int start = width;
 379	int end = width;
 380
 381	for (j = 0; j < width; j++) {
 382		if (back[j] != front[j]) {
 383			start = j;
 384			break;
 385		}
 386	}
 387
 388	for (k = width - 1; k > j; k--) {
 389		if (back[k] != front[k]) {
 390			end = k+1;
 391			break;
 392		}
 393	}
 394
 395	identical = start + (width - end);
 396	*bfront = (u8 *) &front[start];
 397	*width_bytes = (end - start) * sizeof(unsigned long);
 398
 399	return identical * sizeof(unsigned long);
 400}
 401
 402/*
 403 * Render a command stream for an encoded horizontal line segment of pixels.
 404 *
 405 * A command buffer holds several commands.
 406 * It always begins with a fresh command header
 407 * (the protocol doesn't require this, but we enforce it to allow
 408 * multiple buffers to be potentially encoded and sent in parallel).
 409 * A single command encodes one contiguous horizontal line of pixels
 410 *
 411 * The function relies on the client to do all allocation, so that
 412 * rendering can be done directly to output buffers (e.g. USB URBs).
 413 * The function fills the supplied command buffer, providing information
 414 * on where it left off, so the client may call in again with additional
 415 * buffers if the line will take several buffers to complete.
 416 *
 417 * A single command can transmit a maximum of 256 pixels,
 418 * regardless of the compression ratio (protocol design limit).
 419 * To the hardware, 0 for a size byte means 256
 420 *
 421 * Rather than 256 pixel commands which are either rl or raw encoded,
 422 * the rlx command simply assumes alternating raw and rl spans within one cmd.
 423 * This has a slightly larger header overhead, but produces more even results.
 424 * It also processes all data (read and write) in a single pass.
 425 * Performance benchmarks of common cases show it having just slightly better
 426 * compression than 256 pixel raw or rle commands, with similar CPU consumpion.
 427 * But for very rl friendly data, will compress not quite as well.
 428 */
 429static void dlfb_compress_hline(
 430	const uint16_t **pixel_start_ptr,
 431	const uint16_t *const pixel_end,
 432	uint32_t *device_address_ptr,
 433	uint8_t **command_buffer_ptr,
 434	const uint8_t *const cmd_buffer_end,
 435	unsigned long back_buffer_offset,
 436	int *ident_ptr)
 437{
 438	const uint16_t *pixel = *pixel_start_ptr;
 439	uint32_t dev_addr  = *device_address_ptr;
 440	uint8_t *cmd = *command_buffer_ptr;
 441
 442	while ((pixel_end > pixel) &&
 443	       (cmd_buffer_end - MIN_RLX_CMD_BYTES > cmd)) {
 444		uint8_t *raw_pixels_count_byte = NULL;
 445		uint8_t *cmd_pixels_count_byte = NULL;
 446		const uint16_t *raw_pixel_start = NULL;
 447		const uint16_t *cmd_pixel_start, *cmd_pixel_end = NULL;
 448
 449		if (back_buffer_offset &&
 450		    *pixel == *(u16 *)((u8 *)pixel + back_buffer_offset)) {
 451			pixel++;
 452			dev_addr += BPP;
 453			(*ident_ptr)++;
 454			continue;
 455		}
 456
 457		*cmd++ = 0xAF;
 458		*cmd++ = 0x6B;
 459		*cmd++ = dev_addr >> 16;
 460		*cmd++ = dev_addr >> 8;
 461		*cmd++ = dev_addr;
 462
 463		cmd_pixels_count_byte = cmd++; /*  we'll know this later */
 464		cmd_pixel_start = pixel;
 465
 466		raw_pixels_count_byte = cmd++; /*  we'll know this later */
 467		raw_pixel_start = pixel;
 468
 469		cmd_pixel_end = pixel + min3(MAX_CMD_PIXELS + 1UL,
 470					(unsigned long)(pixel_end - pixel),
 471					(unsigned long)(cmd_buffer_end - 1 - cmd) / BPP);
 472
 473		if (back_buffer_offset) {
 474			/* note: the framebuffer may change under us, so we must test for underflow */
 475			while (cmd_pixel_end - 1 > pixel &&
 476			       *(cmd_pixel_end - 1) == *(u16 *)((u8 *)(cmd_pixel_end - 1) + back_buffer_offset))
 477				cmd_pixel_end--;
 478		}
 479
 480		while (pixel < cmd_pixel_end) {
 481			const uint16_t * const repeating_pixel = pixel;
 482			u16 pixel_value = *pixel;
 483
 484			put_unaligned_be16(pixel_value, cmd);
 485			if (back_buffer_offset)
 486				*(u16 *)((u8 *)pixel + back_buffer_offset) = pixel_value;
 487			cmd += 2;
 488			pixel++;
 489
 490			if (unlikely((pixel < cmd_pixel_end) &&
 491				     (*pixel == pixel_value))) {
 492				/* go back and fill in raw pixel count */
 493				*raw_pixels_count_byte = ((repeating_pixel -
 494						raw_pixel_start) + 1) & 0xFF;
 495
 496				do {
 497					if (back_buffer_offset)
 498						*(u16 *)((u8 *)pixel + back_buffer_offset) = pixel_value;
 499					pixel++;
 500				} while ((pixel < cmd_pixel_end) &&
 501					 (*pixel == pixel_value));
 502
 503				/* immediately after raw data is repeat byte */
 504				*cmd++ = ((pixel - repeating_pixel) - 1) & 0xFF;
 505
 506				/* Then start another raw pixel span */
 507				raw_pixel_start = pixel;
 508				raw_pixels_count_byte = cmd++;
 509			}
 510		}
 511
 512		if (pixel > raw_pixel_start) {
 513			/* finalize last RAW span */
 514			*raw_pixels_count_byte = (pixel-raw_pixel_start) & 0xFF;
 515		} else {
 516			/* undo unused byte */
 517			cmd--;
 518		}
 519
 520		*cmd_pixels_count_byte = (pixel - cmd_pixel_start) & 0xFF;
 521		dev_addr += (u8 *)pixel - (u8 *)cmd_pixel_start;
 522	}
 523
 524	if (cmd_buffer_end - MIN_RLX_CMD_BYTES <= cmd) {
 525		/* Fill leftover bytes with no-ops */
 526		if (cmd_buffer_end > cmd)
 527			memset(cmd, 0xAF, cmd_buffer_end - cmd);
 528		cmd = (uint8_t *) cmd_buffer_end;
 529	}
 530
 531	*command_buffer_ptr = cmd;
 532	*pixel_start_ptr = pixel;
 533	*device_address_ptr = dev_addr;
 534}
 535
 536/*
 537 * There are 3 copies of every pixel: The front buffer that the fbdev
 538 * client renders to, the actual framebuffer across the USB bus in hardware
 539 * (that we can only write to, slowly, and can never read), and (optionally)
 540 * our shadow copy that tracks what's been sent to that hardware buffer.
 541 */
 542static int dlfb_render_hline(struct dlfb_data *dlfb, struct urb **urb_ptr,
 543			      const char *front, char **urb_buf_ptr,
 544			      u32 byte_offset, u32 byte_width,
 545			      int *ident_ptr, int *sent_ptr)
 546{
 547	const u8 *line_start, *line_end, *next_pixel;
 548	u32 dev_addr = dlfb->base16 + byte_offset;
 549	struct urb *urb = *urb_ptr;
 550	u8 *cmd = *urb_buf_ptr;
 551	u8 *cmd_end = (u8 *) urb->transfer_buffer + urb->transfer_buffer_length;
 552	unsigned long back_buffer_offset = 0;
 553
 554	line_start = (u8 *) (front + byte_offset);
 555	next_pixel = line_start;
 556	line_end = next_pixel + byte_width;
 557
 558	if (dlfb->backing_buffer) {
 559		int offset;
 560		const u8 *back_start = (u8 *) (dlfb->backing_buffer
 561						+ byte_offset);
 562
 563		back_buffer_offset = (unsigned long)back_start - (unsigned long)line_start;
 564
 565		*ident_ptr += dlfb_trim_hline(back_start, &next_pixel,
 566			&byte_width);
 567
 568		offset = next_pixel - line_start;
 569		line_end = next_pixel + byte_width;
 570		dev_addr += offset;
 571		back_start += offset;
 572		line_start += offset;
 573	}
 574
 575	while (next_pixel < line_end) {
 576
 577		dlfb_compress_hline((const uint16_t **) &next_pixel,
 578			     (const uint16_t *) line_end, &dev_addr,
 579			(u8 **) &cmd, (u8 *) cmd_end, back_buffer_offset,
 580			ident_ptr);
 581
 582		if (cmd >= cmd_end) {
 583			int len = cmd - (u8 *) urb->transfer_buffer;
 584			if (dlfb_submit_urb(dlfb, urb, len))
 585				return 1; /* lost pixels is set */
 586			*sent_ptr += len;
 587			urb = dlfb_get_urb(dlfb);
 588			if (!urb)
 589				return 1; /* lost_pixels is set */
 590			*urb_ptr = urb;
 591			cmd = urb->transfer_buffer;
 592			cmd_end = &cmd[urb->transfer_buffer_length];
 593		}
 594	}
 595
 596	*urb_buf_ptr = cmd;
 597
 598	return 0;
 599}
 600
 601static int dlfb_handle_damage(struct dlfb_data *dlfb, int x, int y, int width, int height)
 602{
 603	int i, ret;
 604	char *cmd;
 605	cycles_t start_cycles, end_cycles;
 606	int bytes_sent = 0;
 607	int bytes_identical = 0;
 608	struct urb *urb;
 609	int aligned_x;
 610
 611	start_cycles = get_cycles();
 612
 613	mutex_lock(&dlfb->render_mutex);
 614
 615	aligned_x = DL_ALIGN_DOWN(x, sizeof(unsigned long));
 616	width = DL_ALIGN_UP(width + (x-aligned_x), sizeof(unsigned long));
 617	x = aligned_x;
 618
 619	if ((width <= 0) ||
 620	    (x + width > dlfb->info->var.xres) ||
 621	    (y + height > dlfb->info->var.yres)) {
 622		ret = -EINVAL;
 623		goto unlock_ret;
 624	}
 625
 626	if (!atomic_read(&dlfb->usb_active)) {
 627		ret = 0;
 628		goto unlock_ret;
 629	}
 630
 631	urb = dlfb_get_urb(dlfb);
 632	if (!urb) {
 633		ret = 0;
 634		goto unlock_ret;
 635	}
 636	cmd = urb->transfer_buffer;
 637
 638	for (i = y; i < y + height ; i++) {
 639		const int line_offset = dlfb->info->fix.line_length * i;
 640		const int byte_offset = line_offset + (x * BPP);
 641
 642		if (dlfb_render_hline(dlfb, &urb,
 643				      (char *) dlfb->info->fix.smem_start,
 644				      &cmd, byte_offset, width * BPP,
 645				      &bytes_identical, &bytes_sent))
 646			goto error;
 647	}
 648
 649	if (cmd > (char *) urb->transfer_buffer) {
 650		int len;
 651		if (cmd < (char *) urb->transfer_buffer + urb->transfer_buffer_length)
 652			*cmd++ = 0xAF;
 653		/* Send partial buffer remaining before exiting */
 654		len = cmd - (char *) urb->transfer_buffer;
 655		dlfb_submit_urb(dlfb, urb, len);
 656		bytes_sent += len;
 657	} else
 658		dlfb_urb_completion(urb);
 659
 660error:
 661	atomic_add(bytes_sent, &dlfb->bytes_sent);
 662	atomic_add(bytes_identical, &dlfb->bytes_identical);
 663	atomic_add(width*height*2, &dlfb->bytes_rendered);
 664	end_cycles = get_cycles();
 665	atomic_add(((unsigned int) ((end_cycles - start_cycles)
 666		    >> 10)), /* Kcycles */
 667		   &dlfb->cpu_kcycles_used);
 668
 669	ret = 0;
 670
 671unlock_ret:
 672	mutex_unlock(&dlfb->render_mutex);
 673	return ret;
 674}
 675
 676static void dlfb_init_damage(struct dlfb_data *dlfb)
 677{
 678	dlfb->damage_x = INT_MAX;
 679	dlfb->damage_x2 = 0;
 680	dlfb->damage_y = INT_MAX;
 681	dlfb->damage_y2 = 0;
 682}
 683
 684static void dlfb_damage_work(struct work_struct *w)
 685{
 686	struct dlfb_data *dlfb = container_of(w, struct dlfb_data, damage_work);
 687	int x, x2, y, y2;
 688
 689	spin_lock_irq(&dlfb->damage_lock);
 690	x = dlfb->damage_x;
 691	x2 = dlfb->damage_x2;
 692	y = dlfb->damage_y;
 693	y2 = dlfb->damage_y2;
 694	dlfb_init_damage(dlfb);
 695	spin_unlock_irq(&dlfb->damage_lock);
 696
 697	if (x < x2 && y < y2)
 698		dlfb_handle_damage(dlfb, x, y, x2 - x, y2 - y);
 699}
 700
 701static void dlfb_offload_damage(struct dlfb_data *dlfb, int x, int y, int width, int height)
 702{
 703	unsigned long flags;
 704	int x2 = x + width;
 705	int y2 = y + height;
 706
 707	if (x >= x2 || y >= y2)
 708		return;
 709
 710	spin_lock_irqsave(&dlfb->damage_lock, flags);
 711	dlfb->damage_x = min(x, dlfb->damage_x);
 712	dlfb->damage_x2 = max(x2, dlfb->damage_x2);
 713	dlfb->damage_y = min(y, dlfb->damage_y);
 714	dlfb->damage_y2 = max(y2, dlfb->damage_y2);
 715	spin_unlock_irqrestore(&dlfb->damage_lock, flags);
 716
 717	schedule_work(&dlfb->damage_work);
 718}
 719
 720/*
 721 * NOTE: fb_defio.c is holding info->fbdefio.mutex
 722 *   Touching ANY framebuffer memory that triggers a page fault
 723 *   in fb_defio will cause a deadlock, when it also tries to
 724 *   grab the same mutex.
 725 */
 726static void dlfb_dpy_deferred_io(struct fb_info *info, struct list_head *pagereflist)
 727{
 728	struct fb_deferred_io_pageref *pageref;
 729	struct dlfb_data *dlfb = info->par;
 730	struct urb *urb;
 731	char *cmd;
 732	cycles_t start_cycles, end_cycles;
 733	int bytes_sent = 0;
 734	int bytes_identical = 0;
 735	int bytes_rendered = 0;
 736
 737	mutex_lock(&dlfb->render_mutex);
 738
 739	if (!fb_defio)
 740		goto unlock_ret;
 741
 742	if (!atomic_read(&dlfb->usb_active))
 743		goto unlock_ret;
 744
 745	start_cycles = get_cycles();
 746
 747	urb = dlfb_get_urb(dlfb);
 748	if (!urb)
 749		goto unlock_ret;
 750
 751	cmd = urb->transfer_buffer;
 752
 753	/* walk the written page list and render each to device */
 754	list_for_each_entry(pageref, pagereflist, list) {
 755		if (dlfb_render_hline(dlfb, &urb, (char *) info->fix.smem_start,
 756				      &cmd, pageref->offset, PAGE_SIZE,
 757				      &bytes_identical, &bytes_sent))
 758			goto error;
 759		bytes_rendered += PAGE_SIZE;
 760	}
 761
 762	if (cmd > (char *) urb->transfer_buffer) {
 763		int len;
 764		if (cmd < (char *) urb->transfer_buffer + urb->transfer_buffer_length)
 765			*cmd++ = 0xAF;
 766		/* Send partial buffer remaining before exiting */
 767		len = cmd - (char *) urb->transfer_buffer;
 768		dlfb_submit_urb(dlfb, urb, len);
 769		bytes_sent += len;
 770	} else
 771		dlfb_urb_completion(urb);
 772
 773error:
 774	atomic_add(bytes_sent, &dlfb->bytes_sent);
 775	atomic_add(bytes_identical, &dlfb->bytes_identical);
 776	atomic_add(bytes_rendered, &dlfb->bytes_rendered);
 777	end_cycles = get_cycles();
 778	atomic_add(((unsigned int) ((end_cycles - start_cycles)
 779		    >> 10)), /* Kcycles */
 780		   &dlfb->cpu_kcycles_used);
 781unlock_ret:
 782	mutex_unlock(&dlfb->render_mutex);
 783}
 784
 785static int dlfb_get_edid(struct dlfb_data *dlfb, char *edid, int len)
 786{
 787	int i, ret;
 788	char *rbuf;
 789
 790	rbuf = kmalloc(2, GFP_KERNEL);
 791	if (!rbuf)
 792		return 0;
 793
 794	for (i = 0; i < len; i++) {
 795		ret = usb_control_msg(dlfb->udev,
 796				      usb_rcvctrlpipe(dlfb->udev, 0), 0x02,
 797				      (0x80 | (0x02 << 5)), i << 8, 0xA1,
 798				      rbuf, 2, USB_CTRL_GET_TIMEOUT);
 799		if (ret < 2) {
 800			dev_err(&dlfb->udev->dev,
 801				"Read EDID byte %d failed: %d\n", i, ret);
 802			i--;
 803			break;
 804		}
 805		edid[i] = rbuf[1];
 806	}
 807
 808	kfree(rbuf);
 809
 810	return i;
 811}
 812
 813static int dlfb_ops_ioctl(struct fb_info *info, unsigned int cmd,
 814				unsigned long arg)
 815{
 816
 817	struct dlfb_data *dlfb = info->par;
 818
 819	if (!atomic_read(&dlfb->usb_active))
 820		return 0;
 821
 822	/* TODO: Update X server to get this from sysfs instead */
 823	if (cmd == DLFB_IOCTL_RETURN_EDID) {
 824		void __user *edid = (void __user *)arg;
 825		if (copy_to_user(edid, dlfb->edid, dlfb->edid_size))
 826			return -EFAULT;
 827		return 0;
 828	}
 829
 830	/* TODO: Help propose a standard fb.h ioctl to report mmap damage */
 831	if (cmd == DLFB_IOCTL_REPORT_DAMAGE) {
 832		struct dloarea area;
 833
 834		if (copy_from_user(&area, (void __user *)arg,
 835				  sizeof(struct dloarea)))
 836			return -EFAULT;
 837
 838		/*
 839		 * If we have a damage-aware client, turn fb_defio "off"
 840		 * To avoid perf imact of unnecessary page fault handling.
 841		 * Done by resetting the delay for this fb_info to a very
 842		 * long period. Pages will become writable and stay that way.
 843		 * Reset to normal value when all clients have closed this fb.
 844		 */
 845		if (info->fbdefio)
 846			info->fbdefio->delay = DL_DEFIO_WRITE_DISABLE;
 847
 848		if (area.x < 0)
 849			area.x = 0;
 850
 851		if (area.x > info->var.xres)
 852			area.x = info->var.xres;
 853
 854		if (area.y < 0)
 855			area.y = 0;
 856
 857		if (area.y > info->var.yres)
 858			area.y = info->var.yres;
 859
 860		dlfb_handle_damage(dlfb, area.x, area.y, area.w, area.h);
 861	}
 862
 863	return 0;
 864}
 865
 866/* taken from vesafb */
 867static int
 868dlfb_ops_setcolreg(unsigned regno, unsigned red, unsigned green,
 869	       unsigned blue, unsigned transp, struct fb_info *info)
 870{
 871	int err = 0;
 872
 873	if (regno >= info->cmap.len)
 874		return 1;
 875
 876	if (regno < 16) {
 877		if (info->var.red.offset == 10) {
 878			/* 1:5:5:5 */
 879			((u32 *) (info->pseudo_palette))[regno] =
 880			    ((red & 0xf800) >> 1) |
 881			    ((green & 0xf800) >> 6) | ((blue & 0xf800) >> 11);
 882		} else {
 883			/* 0:5:6:5 */
 884			((u32 *) (info->pseudo_palette))[regno] =
 885			    ((red & 0xf800)) |
 886			    ((green & 0xfc00) >> 5) | ((blue & 0xf800) >> 11);
 887		}
 888	}
 889
 890	return err;
 891}
 892
 893/*
 894 * It's common for several clients to have framebuffer open simultaneously.
 895 * e.g. both fbcon and X. Makes things interesting.
 896 * Assumes caller is holding info->lock (for open and release at least)
 897 */
 898static int dlfb_ops_open(struct fb_info *info, int user)
 899{
 900	struct dlfb_data *dlfb = info->par;
 901
 902	/*
 903	 * fbcon aggressively connects to first framebuffer it finds,
 904	 * preventing other clients (X) from working properly. Usually
 905	 * not what the user wants. Fail by default with option to enable.
 906	 */
 907	if ((user == 0) && (!console))
 908		return -EBUSY;
 909
 910	/* If the USB device is gone, we don't accept new opens */
 911	if (dlfb->virtualized)
 912		return -ENODEV;
 913
 914	dlfb->fb_count++;
 915
 916	if (fb_defio && (info->fbdefio == NULL)) {
 917		/* enable defio at last moment if not disabled by client */
 918
 919		struct fb_deferred_io *fbdefio;
 920
 921		fbdefio = kzalloc(sizeof(struct fb_deferred_io), GFP_KERNEL);
 922
 923		if (fbdefio) {
 924			fbdefio->delay = DL_DEFIO_WRITE_DELAY;
 925			fbdefio->sort_pagereflist = true;
 926			fbdefio->deferred_io = dlfb_dpy_deferred_io;
 927		}
 928
 929		info->fbdefio = fbdefio;
 930		fb_deferred_io_init(info);
 931	}
 932
 933	dev_dbg(info->dev, "open, user=%d fb_info=%p count=%d\n",
 934		user, info, dlfb->fb_count);
 935
 936	return 0;
 937}
 938
 939static void dlfb_ops_destroy(struct fb_info *info)
 940{
 941	struct dlfb_data *dlfb = info->par;
 942
 943	cancel_work_sync(&dlfb->damage_work);
 944
 945	mutex_destroy(&dlfb->render_mutex);
 946
 947	if (info->cmap.len != 0)
 948		fb_dealloc_cmap(&info->cmap);
 949	if (info->monspecs.modedb)
 950		fb_destroy_modedb(info->monspecs.modedb);
 951	vfree(info->screen_buffer);
 952
 953	fb_destroy_modelist(&info->modelist);
 954
 955	while (!list_empty(&dlfb->deferred_free)) {
 956		struct dlfb_deferred_free *d = list_entry(dlfb->deferred_free.next, struct dlfb_deferred_free, list);
 957		list_del(&d->list);
 958		vfree(d->mem);
 959		kfree(d);
 960	}
 961	vfree(dlfb->backing_buffer);
 962	kfree(dlfb->edid);
 963	dlfb_free_urb_list(dlfb);
 964	usb_put_dev(dlfb->udev);
 965	kfree(dlfb);
 966
 967	/* Assume info structure is freed after this point */
 968	framebuffer_release(info);
 969}
 970
 971/*
 972 * Assumes caller is holding info->lock mutex (for open and release at least)
 973 */
 974static int dlfb_ops_release(struct fb_info *info, int user)
 975{
 976	struct dlfb_data *dlfb = info->par;
 977
 978	dlfb->fb_count--;
 979
 980	if ((dlfb->fb_count == 0) && (info->fbdefio)) {
 981		fb_deferred_io_cleanup(info);
 982		kfree(info->fbdefio);
 983		info->fbdefio = NULL;
 984	}
 985
 986	dev_dbg(info->dev, "release, user=%d count=%d\n", user, dlfb->fb_count);
 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 */
 995static 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
1003static 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
1015static 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	if (!var->pixclock)
1022		return -EINVAL;
1023
1024	/* set device-specific elements of var unrelated to mode */
1025	dlfb_var_color_format(var);
1026
1027	fb_var_to_videomode(&mode, var);
1028
1029	if (!dlfb_is_valid_mode(&mode, dlfb))
1030		return -EINVAL;
1031
1032	return 0;
1033}
1034
1035static int dlfb_ops_set_par(struct fb_info *info)
1036{
1037	struct dlfb_data *dlfb = info->par;
1038	int result;
1039	u16 *pix_framebuffer;
1040	int i;
1041	struct fb_var_screeninfo fvs;
1042	u32 line_length = info->var.xres * (info->var.bits_per_pixel / 8);
1043
1044	/* clear the activate field because it causes spurious miscompares */
1045	fvs = info->var;
1046	fvs.activate = 0;
1047	fvs.vmode &= ~FB_VMODE_SMOOTH_XPAN;
1048
1049	if (!memcmp(&dlfb->current_mode, &fvs, sizeof(struct fb_var_screeninfo)))
1050		return 0;
1051
1052	result = dlfb_realloc_framebuffer(dlfb, info, info->var.yres * line_length);
1053	if (result)
1054		return result;
1055
1056	result = dlfb_set_video_mode(dlfb, &info->var);
1057
1058	if (result)
1059		return result;
1060
1061	dlfb->current_mode = fvs;
1062	info->fix.line_length = line_length;
1063
1064	if (dlfb->fb_count == 0) {
1065
1066		/* paint greenscreen */
1067
1068		pix_framebuffer = (u16 *)info->screen_buffer;
1069		for (i = 0; i < info->fix.smem_len / 2; i++)
1070			pix_framebuffer[i] = 0x37e6;
1071	}
1072
1073	dlfb_handle_damage(dlfb, 0, 0, info->var.xres, info->var.yres);
1074
1075	return 0;
1076}
1077
1078/* To fonzi the jukebox (e.g. make blanking changes take effect) */
1079static char *dlfb_dummy_render(char *buf)
1080{
1081	*buf++ = 0xAF;
1082	*buf++ = 0x6A; /* copy */
1083	*buf++ = 0x00; /* from address*/
1084	*buf++ = 0x00;
1085	*buf++ = 0x00;
1086	*buf++ = 0x01; /* one pixel */
1087	*buf++ = 0x00; /* to address */
1088	*buf++ = 0x00;
1089	*buf++ = 0x00;
1090	return buf;
1091}
1092
1093/*
1094 * In order to come back from full DPMS off, we need to set the mode again
1095 */
1096static int dlfb_ops_blank(int blank_mode, struct fb_info *info)
1097{
1098	struct dlfb_data *dlfb = info->par;
1099	char *bufptr;
1100	struct urb *urb;
1101
1102	dev_dbg(info->dev, "blank, mode %d --> %d\n",
1103		dlfb->blank_mode, blank_mode);
1104
1105	if ((dlfb->blank_mode == FB_BLANK_POWERDOWN) &&
1106	    (blank_mode != FB_BLANK_POWERDOWN)) {
1107
1108		/* returning from powerdown requires a fresh modeset */
1109		dlfb_set_video_mode(dlfb, &info->var);
1110	}
1111
1112	urb = dlfb_get_urb(dlfb);
1113	if (!urb)
1114		return 0;
1115
1116	bufptr = (char *) urb->transfer_buffer;
1117	bufptr = dlfb_vidreg_lock(bufptr);
1118	bufptr = dlfb_blanking(bufptr, blank_mode);
1119	bufptr = dlfb_vidreg_unlock(bufptr);
1120
1121	/* seems like a render op is needed to have blank change take effect */
1122	bufptr = dlfb_dummy_render(bufptr);
1123
1124	dlfb_submit_urb(dlfb, urb, bufptr -
1125			(char *) urb->transfer_buffer);
1126
1127	dlfb->blank_mode = blank_mode;
1128
1129	return 0;
1130}
1131
1132static void dlfb_ops_damage_range(struct fb_info *info, off_t off, size_t len)
1133{
1134	struct dlfb_data *dlfb = info->par;
1135	int start = max((int)(off / info->fix.line_length), 0);
1136	int lines = min((u32)((len / info->fix.line_length) + 1), (u32)info->var.yres);
1137
1138	dlfb_handle_damage(dlfb, 0, start, info->var.xres, lines);
1139}
1140
1141static void dlfb_ops_damage_area(struct fb_info *info, u32 x, u32 y, u32 width, u32 height)
1142{
1143	struct dlfb_data *dlfb = info->par;
1144
1145	dlfb_offload_damage(dlfb, x, y, width, height);
1146}
1147
1148FB_GEN_DEFAULT_DEFERRED_SYSMEM_OPS(dlfb_ops,
1149				   dlfb_ops_damage_range,
1150				   dlfb_ops_damage_area)
1151
1152static const struct fb_ops dlfb_ops = {
1153	.owner = THIS_MODULE,
1154	__FB_DEFAULT_DEFERRED_OPS_RDWR(dlfb_ops),
1155	.fb_setcolreg = dlfb_ops_setcolreg,
1156	__FB_DEFAULT_DEFERRED_OPS_DRAW(dlfb_ops),
1157	.fb_mmap = dlfb_ops_mmap,
1158	.fb_ioctl = dlfb_ops_ioctl,
1159	.fb_open = dlfb_ops_open,
1160	.fb_release = dlfb_ops_release,
1161	.fb_blank = dlfb_ops_blank,
1162	.fb_check_var = dlfb_ops_check_var,
1163	.fb_set_par = dlfb_ops_set_par,
1164	.fb_destroy = dlfb_ops_destroy,
1165};
1166
1167
1168static void dlfb_deferred_vfree(struct dlfb_data *dlfb, void *mem)
1169{
1170	struct dlfb_deferred_free *d = kmalloc(sizeof(struct dlfb_deferred_free), GFP_KERNEL);
1171	if (!d)
1172		return;
1173	d->mem = mem;
1174	list_add(&d->list, &dlfb->deferred_free);
1175}
1176
1177/*
1178 * Assumes &info->lock held by caller
1179 * Assumes no active clients have framebuffer open
1180 */
1181static int dlfb_realloc_framebuffer(struct dlfb_data *dlfb, struct fb_info *info, u32 new_len)
1182{
1183	u32 old_len = info->fix.smem_len;
1184	const void *old_fb = info->screen_buffer;
1185	unsigned char *new_fb;
1186	unsigned char *new_back = NULL;
1187
1188	new_len = PAGE_ALIGN(new_len);
1189
1190	if (new_len > old_len) {
1191		/*
1192		 * Alloc system memory for virtual framebuffer
1193		 */
1194		new_fb = vmalloc(new_len);
1195		if (!new_fb) {
1196			dev_err(info->dev, "Virtual framebuffer alloc failed\n");
1197			return -ENOMEM;
1198		}
1199		memset(new_fb, 0xff, new_len);
1200
1201		if (info->screen_buffer) {
1202			memcpy(new_fb, old_fb, old_len);
1203			dlfb_deferred_vfree(dlfb, info->screen_buffer);
1204		}
1205
1206		info->screen_buffer = new_fb;
1207		info->fix.smem_len = new_len;
1208		info->fix.smem_start = (unsigned long) new_fb;
1209		info->flags = udlfb_info_flags;
1210
1211		/*
1212		 * Second framebuffer copy to mirror the framebuffer state
1213		 * on the physical USB device. We can function without this.
1214		 * But with imperfect damage info we may send pixels over USB
1215		 * that were, in fact, unchanged - wasting limited USB bandwidth
1216		 */
1217		if (shadow)
1218			new_back = vzalloc(new_len);
1219		if (!new_back)
1220			dev_info(info->dev,
1221				 "No shadow/backing buffer allocated\n");
1222		else {
1223			dlfb_deferred_vfree(dlfb, dlfb->backing_buffer);
1224			dlfb->backing_buffer = new_back;
1225		}
1226	}
1227	return 0;
1228}
1229
1230/*
1231 * 1) Get EDID from hw, or use sw default
1232 * 2) Parse into various fb_info structs
1233 * 3) Allocate virtual framebuffer memory to back highest res mode
1234 *
1235 * Parses EDID into three places used by various parts of fbdev:
1236 * fb_var_screeninfo contains the timing of the monitor's preferred mode
1237 * fb_info.monspecs is full parsed EDID info, including monspecs.modedb
1238 * fb_info.modelist is a linked list of all monitor & VESA modes which work
1239 *
1240 * If EDID is not readable/valid, then modelist is all VESA modes,
1241 * monspecs is NULL, and fb_var_screeninfo is set to safe VESA mode
1242 * Returns 0 if successful
1243 */
1244static int dlfb_setup_modes(struct dlfb_data *dlfb,
1245			   struct fb_info *info,
1246			   char *default_edid, size_t default_edid_size)
1247{
1248	char *edid;
1249	int i, result = 0, tries = 3;
1250	struct device *dev = info->device;
1251	struct fb_videomode *mode;
1252	const struct fb_videomode *default_vmode = NULL;
1253
1254	if (info->dev) {
1255		/* only use mutex if info has been registered */
1256		mutex_lock(&info->lock);
1257		/* parent device is used otherwise */
1258		dev = info->dev;
1259	}
1260
1261	edid = kmalloc(EDID_LENGTH, GFP_KERNEL);
1262	if (!edid) {
1263		result = -ENOMEM;
1264		goto error;
1265	}
1266
1267	fb_destroy_modelist(&info->modelist);
1268	memset(&info->monspecs, 0, sizeof(info->monspecs));
1269
1270	/*
1271	 * Try to (re)read EDID from hardware first
1272	 * EDID data may return, but not parse as valid
1273	 * Try again a few times, in case of e.g. analog cable noise
1274	 */
1275	while (tries--) {
1276
1277		i = dlfb_get_edid(dlfb, edid, EDID_LENGTH);
1278
1279		if (i >= EDID_LENGTH)
1280			fb_edid_to_monspecs(edid, &info->monspecs);
1281
1282		if (info->monspecs.modedb_len > 0) {
1283			dlfb->edid = edid;
1284			dlfb->edid_size = i;
1285			break;
1286		}
1287	}
1288
1289	/* If that fails, use a previously returned EDID if available */
1290	if (info->monspecs.modedb_len == 0) {
1291		dev_err(dev, "Unable to get valid EDID from device/display\n");
1292
1293		if (dlfb->edid) {
1294			fb_edid_to_monspecs(dlfb->edid, &info->monspecs);
1295			if (info->monspecs.modedb_len > 0)
1296				dev_err(dev, "Using previously queried EDID\n");
1297		}
1298	}
1299
1300	/* If that fails, use the default EDID we were handed */
1301	if (info->monspecs.modedb_len == 0) {
1302		if (default_edid_size >= EDID_LENGTH) {
1303			fb_edid_to_monspecs(default_edid, &info->monspecs);
1304			if (info->monspecs.modedb_len > 0) {
1305				memcpy(edid, default_edid, default_edid_size);
1306				dlfb->edid = edid;
1307				dlfb->edid_size = default_edid_size;
1308				dev_err(dev, "Using default/backup EDID\n");
1309			}
1310		}
1311	}
1312
1313	/* If we've got modes, let's pick a best default mode */
1314	if (info->monspecs.modedb_len > 0) {
1315
1316		for (i = 0; i < info->monspecs.modedb_len; i++) {
1317			mode = &info->monspecs.modedb[i];
1318			if (dlfb_is_valid_mode(mode, dlfb)) {
1319				fb_add_videomode(mode, &info->modelist);
1320			} else {
1321				dev_dbg(dev, "Specified mode %dx%d too big\n",
1322					mode->xres, mode->yres);
1323				if (i == 0)
1324					/* if we've removed top/best mode */
1325					info->monspecs.misc
1326						&= ~FB_MISC_1ST_DETAIL;
1327			}
1328		}
1329
1330		default_vmode = fb_find_best_display(&info->monspecs,
1331						     &info->modelist);
1332	}
1333
1334	/* If everything else has failed, fall back to safe default mode */
1335	if (default_vmode == NULL) {
1336
1337		struct fb_videomode fb_vmode = {0};
1338
1339		/*
1340		 * Add the standard VESA modes to our modelist
1341		 * Since we don't have EDID, there may be modes that
1342		 * overspec monitor and/or are incorrect aspect ratio, etc.
1343		 * But at least the user has a chance to choose
1344		 */
1345		for (i = 0; i < VESA_MODEDB_SIZE; i++) {
1346			mode = (struct fb_videomode *)&vesa_modes[i];
1347			if (dlfb_is_valid_mode(mode, dlfb))
1348				fb_add_videomode(mode, &info->modelist);
1349			else
1350				dev_dbg(dev, "VESA mode %dx%d too big\n",
1351					mode->xres, mode->yres);
1352		}
1353
1354		/*
1355		 * default to resolution safe for projectors
1356		 * (since they are most common case without EDID)
1357		 */
1358		fb_vmode.xres = 800;
1359		fb_vmode.yres = 600;
1360		fb_vmode.refresh = 60;
1361		default_vmode = fb_find_nearest_mode(&fb_vmode,
1362						     &info->modelist);
1363	}
1364
1365	/* If we have good mode and no active clients*/
1366	if ((default_vmode != NULL) && (dlfb->fb_count == 0)) {
1367
1368		fb_videomode_to_var(&info->var, default_vmode);
1369		dlfb_var_color_format(&info->var);
1370
1371		/*
1372		 * with mode size info, we can now alloc our framebuffer.
1373		 */
1374		memcpy(&info->fix, &dlfb_fix, sizeof(dlfb_fix));
1375	} else
1376		result = -EINVAL;
1377
1378error:
1379	if (edid && (dlfb->edid != edid))
1380		kfree(edid);
1381
1382	if (info->dev)
1383		mutex_unlock(&info->lock);
1384
1385	return result;
1386}
1387
1388static ssize_t metrics_bytes_rendered_show(struct device *fbdev,
1389				   struct device_attribute *a, char *buf) {
1390	struct fb_info *fb_info = dev_get_drvdata(fbdev);
1391	struct dlfb_data *dlfb = fb_info->par;
1392	return sysfs_emit(buf, "%u\n",
1393			atomic_read(&dlfb->bytes_rendered));
1394}
1395
1396static ssize_t metrics_bytes_identical_show(struct device *fbdev,
1397				   struct device_attribute *a, char *buf) {
1398	struct fb_info *fb_info = dev_get_drvdata(fbdev);
1399	struct dlfb_data *dlfb = fb_info->par;
1400	return sysfs_emit(buf, "%u\n",
1401			atomic_read(&dlfb->bytes_identical));
1402}
1403
1404static ssize_t metrics_bytes_sent_show(struct device *fbdev,
1405				   struct device_attribute *a, char *buf) {
1406	struct fb_info *fb_info = dev_get_drvdata(fbdev);
1407	struct dlfb_data *dlfb = fb_info->par;
1408	return sysfs_emit(buf, "%u\n",
1409			atomic_read(&dlfb->bytes_sent));
1410}
1411
1412static ssize_t metrics_cpu_kcycles_used_show(struct device *fbdev,
1413				   struct device_attribute *a, char *buf) {
1414	struct fb_info *fb_info = dev_get_drvdata(fbdev);
1415	struct dlfb_data *dlfb = fb_info->par;
1416	return sysfs_emit(buf, "%u\n",
1417			atomic_read(&dlfb->cpu_kcycles_used));
1418}
1419
1420static ssize_t edid_show(
1421			struct file *filp,
1422			struct kobject *kobj, const struct bin_attribute *a,
1423			 char *buf, loff_t off, size_t count) {
1424	struct device *fbdev = kobj_to_dev(kobj);
1425	struct fb_info *fb_info = dev_get_drvdata(fbdev);
1426	struct dlfb_data *dlfb = fb_info->par;
1427
1428	if (dlfb->edid == NULL)
1429		return 0;
1430
1431	if ((off >= dlfb->edid_size) || (count > dlfb->edid_size))
1432		return 0;
1433
1434	if (off + count > dlfb->edid_size)
1435		count = dlfb->edid_size - off;
1436
1437	memcpy(buf, dlfb->edid, count);
1438
1439	return count;
1440}
1441
1442static ssize_t edid_store(
1443			struct file *filp,
1444			struct kobject *kobj, const struct bin_attribute *a,
1445			char *src, loff_t src_off, size_t src_size) {
1446	struct device *fbdev = kobj_to_dev(kobj);
1447	struct fb_info *fb_info = dev_get_drvdata(fbdev);
1448	struct dlfb_data *dlfb = fb_info->par;
1449	int ret;
1450
1451	/* We only support write of entire EDID at once, no offset*/
1452	if ((src_size != EDID_LENGTH) || (src_off != 0))
1453		return -EINVAL;
1454
1455	ret = dlfb_setup_modes(dlfb, fb_info, src, src_size);
1456	if (ret)
1457		return ret;
1458
1459	if (!dlfb->edid || memcmp(src, dlfb->edid, src_size))
1460		return -EINVAL;
1461
1462	ret = dlfb_ops_set_par(fb_info);
1463	if (ret)
1464		return ret;
1465
1466	return src_size;
1467}
1468
1469static ssize_t metrics_reset_store(struct device *fbdev,
1470			   struct device_attribute *attr,
1471			   const char *buf, size_t count)
1472{
1473	struct fb_info *fb_info = dev_get_drvdata(fbdev);
1474	struct dlfb_data *dlfb = fb_info->par;
1475
1476	atomic_set(&dlfb->bytes_rendered, 0);
1477	atomic_set(&dlfb->bytes_identical, 0);
1478	atomic_set(&dlfb->bytes_sent, 0);
1479	atomic_set(&dlfb->cpu_kcycles_used, 0);
1480
1481	return count;
1482}
1483
1484static const struct bin_attribute edid_attr = {
1485	.attr.name = "edid",
1486	.attr.mode = 0666,
1487	.size = EDID_LENGTH,
1488	.read = edid_show,
1489	.write = edid_store
1490};
1491
1492static const struct device_attribute fb_device_attrs[] = {
1493	__ATTR_RO(metrics_bytes_rendered),
1494	__ATTR_RO(metrics_bytes_identical),
1495	__ATTR_RO(metrics_bytes_sent),
1496	__ATTR_RO(metrics_cpu_kcycles_used),
1497	__ATTR(metrics_reset, S_IWUSR, NULL, metrics_reset_store),
1498};
1499
1500/*
1501 * This is necessary before we can communicate with the display controller.
1502 */
1503static int dlfb_select_std_channel(struct dlfb_data *dlfb)
1504{
1505	int ret;
1506	static const u8 set_def_chn[] = {
1507				0x57, 0xCD, 0xDC, 0xA7,
1508				0x1C, 0x88, 0x5E, 0x15,
1509				0x60, 0xFE, 0xC6, 0x97,
1510				0x16, 0x3D, 0x47, 0xF2  };
1511
1512	ret = usb_control_msg_send(dlfb->udev, 0, NR_USB_REQUEST_CHANNEL,
1513			(USB_DIR_OUT | USB_TYPE_VENDOR), 0, 0,
1514			&set_def_chn, sizeof(set_def_chn), USB_CTRL_SET_TIMEOUT,
1515			GFP_KERNEL);
1516
1517	return ret;
1518}
1519
1520static int dlfb_parse_vendor_descriptor(struct dlfb_data *dlfb,
1521					struct usb_interface *intf)
1522{
1523	char *desc;
1524	char *buf;
1525	char *desc_end;
1526	int total_len;
1527
1528	buf = kzalloc(MAX_VENDOR_DESCRIPTOR_SIZE, GFP_KERNEL);
1529	if (!buf)
1530		return false;
1531	desc = buf;
1532
1533	total_len = usb_get_descriptor(interface_to_usbdev(intf),
1534					0x5f, /* vendor specific */
1535					0, desc, MAX_VENDOR_DESCRIPTOR_SIZE);
1536
1537	/* if not found, look in configuration descriptor */
1538	if (total_len < 0) {
1539		if (0 == usb_get_extra_descriptor(intf->cur_altsetting,
1540			0x5f, &desc))
1541			total_len = (int) desc[0];
1542	}
1543
1544	if (total_len > 5) {
1545		dev_info(&intf->dev,
1546			 "vendor descriptor length: %d data: %11ph\n",
1547			 total_len, desc);
1548
1549		if ((desc[0] != total_len) || /* descriptor length */
1550		    (desc[1] != 0x5f) ||   /* vendor descriptor type */
1551		    (desc[2] != 0x01) ||   /* version (2 bytes) */
1552		    (desc[3] != 0x00) ||
1553		    (desc[4] != total_len - 2)) /* length after type */
1554			goto unrecognized;
1555
1556		desc_end = desc + total_len;
1557		desc += 5; /* the fixed header we've already parsed */
1558
1559		while (desc < desc_end) {
1560			u8 length;
1561			u16 key;
1562
1563			key = *desc++;
1564			key |= (u16)*desc++ << 8;
1565			length = *desc++;
1566
1567			switch (key) {
1568			case 0x0200: { /* max_area */
1569				u32 max_area = *desc++;
1570				max_area |= (u32)*desc++ << 8;
1571				max_area |= (u32)*desc++ << 16;
1572				max_area |= (u32)*desc++ << 24;
1573				dev_warn(&intf->dev,
1574					 "DL chip limited to %d pixel modes\n",
1575					 max_area);
1576				dlfb->sku_pixel_limit = max_area;
1577				break;
1578			}
1579			default:
1580				break;
1581			}
1582			desc += length;
1583		}
1584	} else {
1585		dev_info(&intf->dev, "vendor descriptor not available (%d)\n",
1586			 total_len);
1587	}
1588
1589	goto success;
1590
1591unrecognized:
1592	/* allow udlfb to load for now even if firmware unrecognized */
1593	dev_err(&intf->dev, "Unrecognized vendor firmware descriptor\n");
1594
1595success:
1596	kfree(buf);
1597	return true;
1598}
1599
1600static int dlfb_usb_probe(struct usb_interface *intf,
1601			  const struct usb_device_id *id)
1602{
1603	int i;
1604	const struct device_attribute *attr;
1605	struct dlfb_data *dlfb;
1606	struct fb_info *info;
1607	int retval;
1608	struct usb_device *usbdev = interface_to_usbdev(intf);
1609	static u8 out_ep[] = {OUT_EP_NUM + USB_DIR_OUT, 0};
1610
1611	/* usb initialization */
1612	dlfb = kzalloc(sizeof(*dlfb), GFP_KERNEL);
1613	if (!dlfb) {
1614		dev_err(&intf->dev, "%s: failed to allocate dlfb\n", __func__);
1615		return -ENOMEM;
1616	}
1617
1618	INIT_LIST_HEAD(&dlfb->deferred_free);
1619
1620	dlfb->udev = usb_get_dev(usbdev);
1621	usb_set_intfdata(intf, dlfb);
1622
1623	if (!usb_check_bulk_endpoints(intf, out_ep)) {
1624		dev_err(&intf->dev, "Invalid DisplayLink device!\n");
1625		retval = -EINVAL;
1626		goto error;
1627	}
1628
1629	dev_dbg(&intf->dev, "console enable=%d\n", console);
1630	dev_dbg(&intf->dev, "fb_defio enable=%d\n", fb_defio);
1631	dev_dbg(&intf->dev, "shadow enable=%d\n", shadow);
1632
1633	dlfb->sku_pixel_limit = 2048 * 1152; /* default to maximum */
1634
1635	if (!dlfb_parse_vendor_descriptor(dlfb, intf)) {
1636		dev_err(&intf->dev,
1637			"firmware not recognized, incompatible device?\n");
1638		retval = -ENODEV;
1639		goto error;
1640	}
1641
1642	if (pixel_limit) {
1643		dev_warn(&intf->dev,
1644			 "DL chip limit of %d overridden to %d\n",
1645			 dlfb->sku_pixel_limit, pixel_limit);
1646		dlfb->sku_pixel_limit = pixel_limit;
1647	}
1648
1649
1650	/* allocates framebuffer driver structure, not framebuffer memory */
1651	info = framebuffer_alloc(0, &dlfb->udev->dev);
1652	if (!info) {
1653		retval = -ENOMEM;
1654		goto error;
1655	}
1656
1657	dlfb->info = info;
1658	info->par = dlfb;
1659	info->pseudo_palette = dlfb->pseudo_palette;
1660	dlfb->ops = dlfb_ops;
1661	info->fbops = &dlfb->ops;
1662
1663	mutex_init(&dlfb->render_mutex);
1664	dlfb_init_damage(dlfb);
1665	spin_lock_init(&dlfb->damage_lock);
1666	INIT_WORK(&dlfb->damage_work, dlfb_damage_work);
1667
1668	INIT_LIST_HEAD(&info->modelist);
1669
1670	if (!dlfb_alloc_urb_list(dlfb, WRITES_IN_FLIGHT, MAX_TRANSFER)) {
1671		retval = -ENOMEM;
1672		dev_err(&intf->dev, "unable to allocate urb list\n");
1673		goto error;
1674	}
1675
1676	/* We don't register a new USB class. Our client interface is dlfbev */
1677
1678	retval = fb_alloc_cmap(&info->cmap, 256, 0);
1679	if (retval < 0) {
1680		dev_err(info->device, "cmap allocation failed: %d\n", retval);
1681		goto error;
1682	}
1683
1684	retval = dlfb_setup_modes(dlfb, info, NULL, 0);
1685	if (retval != 0) {
1686		dev_err(info->device,
1687			"unable to find common mode for display and adapter\n");
1688		goto error;
1689	}
1690
1691	/* ready to begin using device */
1692
1693	atomic_set(&dlfb->usb_active, 1);
1694	dlfb_select_std_channel(dlfb);
1695
1696	dlfb_ops_check_var(&info->var, info);
1697	retval = dlfb_ops_set_par(info);
1698	if (retval)
1699		goto error;
1700
1701	retval = register_framebuffer(info);
1702	if (retval < 0) {
1703		dev_err(info->device, "unable to register framebuffer: %d\n",
1704			retval);
1705		goto error;
1706	}
1707
1708	for (i = 0; i < ARRAY_SIZE(fb_device_attrs); i++) {
1709		attr = &fb_device_attrs[i];
1710		retval = device_create_file(info->dev, attr);
1711		if (retval)
1712			dev_warn(info->device,
1713				 "failed to create '%s' attribute: %d\n",
1714				 attr->attr.name, retval);
1715	}
1716
1717	retval = device_create_bin_file(info->dev, &edid_attr);
1718	if (retval)
1719		dev_warn(info->device, "failed to create '%s' attribute: %d\n",
1720			 edid_attr.attr.name, retval);
1721
1722	dev_info(info->device,
1723		 "%s is DisplayLink USB device (%dx%d, %dK framebuffer memory)\n",
1724		 dev_name(info->dev), info->var.xres, info->var.yres,
1725		 ((dlfb->backing_buffer) ?
1726		 info->fix.smem_len * 2 : info->fix.smem_len) >> 10);
1727	return 0;
1728
1729error:
1730	if (dlfb->info) {
1731		dlfb_ops_destroy(dlfb->info);
1732	} else {
1733		usb_put_dev(dlfb->udev);
1734		kfree(dlfb);
1735	}
1736	return retval;
1737}
1738
1739static void dlfb_usb_disconnect(struct usb_interface *intf)
1740{
1741	struct dlfb_data *dlfb;
1742	struct fb_info *info;
1743	int i;
1744
1745	dlfb = usb_get_intfdata(intf);
1746	info = dlfb->info;
1747
1748	dev_dbg(&intf->dev, "USB disconnect starting\n");
1749
1750	/* we virtualize until all fb clients release. Then we free */
1751	dlfb->virtualized = true;
1752
1753	/* When non-active we'll update virtual framebuffer, but no new urbs */
1754	atomic_set(&dlfb->usb_active, 0);
1755
1756	/* this function will wait for all in-flight urbs to complete */
1757	dlfb_free_urb_list(dlfb);
1758
1759	/* remove udlfb's sysfs interfaces */
1760	for (i = 0; i < ARRAY_SIZE(fb_device_attrs); i++)
1761		device_remove_file(info->dev, &fb_device_attrs[i]);
1762	device_remove_bin_file(info->dev, &edid_attr);
1763
1764	unregister_framebuffer(info);
1765}
1766
1767static struct usb_driver dlfb_driver = {
1768	.name = "udlfb",
1769	.probe = dlfb_usb_probe,
1770	.disconnect = dlfb_usb_disconnect,
1771	.id_table = id_table,
1772};
1773
1774module_usb_driver(dlfb_driver);
1775
1776static void dlfb_urb_completion(struct urb *urb)
1777{
1778	struct urb_node *unode = urb->context;
1779	struct dlfb_data *dlfb = unode->dlfb;
1780	unsigned long flags;
1781
1782	switch (urb->status) {
1783	case 0:
1784		/* success */
1785		break;
1786	case -ECONNRESET:
1787	case -ENOENT:
1788	case -ESHUTDOWN:
1789		/* sync/async unlink faults aren't errors */
1790		break;
1791	default:
1792		dev_err(&dlfb->udev->dev,
1793			"%s - nonzero write bulk status received: %d\n",
1794			__func__, urb->status);
1795		atomic_set(&dlfb->lost_pixels, 1);
1796		break;
1797	}
1798
1799	urb->transfer_buffer_length = dlfb->urbs.size; /* reset to actual */
1800
1801	spin_lock_irqsave(&dlfb->urbs.lock, flags);
1802	list_add_tail(&unode->entry, &dlfb->urbs.list);
1803	dlfb->urbs.available++;
1804	spin_unlock_irqrestore(&dlfb->urbs.lock, flags);
1805
1806	up(&dlfb->urbs.limit_sem);
1807}
1808
1809static void dlfb_free_urb_list(struct dlfb_data *dlfb)
1810{
1811	int count = dlfb->urbs.count;
1812	struct list_head *node;
1813	struct urb_node *unode;
1814	struct urb *urb;
1815
1816	/* keep waiting and freeing, until we've got 'em all */
1817	while (count--) {
1818		down(&dlfb->urbs.limit_sem);
1819
1820		spin_lock_irq(&dlfb->urbs.lock);
1821
1822		node = dlfb->urbs.list.next; /* have reserved one with sem */
1823		list_del_init(node);
1824
1825		spin_unlock_irq(&dlfb->urbs.lock);
1826
1827		unode = list_entry(node, struct urb_node, entry);
1828		urb = unode->urb;
1829
1830		/* Free each separately allocated piece */
1831		usb_free_coherent(urb->dev, dlfb->urbs.size,
1832				  urb->transfer_buffer, urb->transfer_dma);
1833		usb_free_urb(urb);
1834		kfree(node);
1835	}
1836
1837	dlfb->urbs.count = 0;
1838}
1839
1840static int dlfb_alloc_urb_list(struct dlfb_data *dlfb, int count, size_t size)
1841{
1842	struct urb *urb;
1843	struct urb_node *unode;
1844	char *buf;
1845	size_t wanted_size = count * size;
1846
1847	spin_lock_init(&dlfb->urbs.lock);
1848
1849retry:
1850	dlfb->urbs.size = size;
1851	INIT_LIST_HEAD(&dlfb->urbs.list);
1852
1853	sema_init(&dlfb->urbs.limit_sem, 0);
1854	dlfb->urbs.count = 0;
1855	dlfb->urbs.available = 0;
1856
1857	while (dlfb->urbs.count * size < wanted_size) {
1858		unode = kzalloc(sizeof(*unode), GFP_KERNEL);
1859		if (!unode)
1860			break;
1861		unode->dlfb = dlfb;
1862
1863		urb = usb_alloc_urb(0, GFP_KERNEL);
1864		if (!urb) {
1865			kfree(unode);
1866			break;
1867		}
1868		unode->urb = urb;
1869
1870		buf = usb_alloc_coherent(dlfb->udev, size, GFP_KERNEL,
1871					 &urb->transfer_dma);
1872		if (!buf) {
1873			kfree(unode);
1874			usb_free_urb(urb);
1875			if (size > PAGE_SIZE) {
1876				size /= 2;
1877				dlfb_free_urb_list(dlfb);
1878				goto retry;
1879			}
1880			break;
1881		}
1882
1883		/* urb->transfer_buffer_length set to actual before submit */
1884		usb_fill_bulk_urb(urb, dlfb->udev,
1885			usb_sndbulkpipe(dlfb->udev, OUT_EP_NUM),
1886			buf, size, dlfb_urb_completion, unode);
1887		urb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;
1888
1889		list_add_tail(&unode->entry, &dlfb->urbs.list);
1890
1891		up(&dlfb->urbs.limit_sem);
1892		dlfb->urbs.count++;
1893		dlfb->urbs.available++;
1894	}
1895
1896	return dlfb->urbs.count;
1897}
1898
1899static struct urb *dlfb_get_urb(struct dlfb_data *dlfb)
1900{
1901	int ret;
1902	struct list_head *entry;
1903	struct urb_node *unode;
1904
1905	/* Wait for an in-flight buffer to complete and get re-queued */
1906	ret = down_timeout(&dlfb->urbs.limit_sem, GET_URB_TIMEOUT);
1907	if (ret) {
1908		atomic_set(&dlfb->lost_pixels, 1);
1909		dev_warn(&dlfb->udev->dev,
1910			 "wait for urb interrupted: %d available: %d\n",
1911			 ret, dlfb->urbs.available);
1912		return NULL;
1913	}
1914
1915	spin_lock_irq(&dlfb->urbs.lock);
1916
1917	BUG_ON(list_empty(&dlfb->urbs.list)); /* reserved one with limit_sem */
1918	entry = dlfb->urbs.list.next;
1919	list_del_init(entry);
1920	dlfb->urbs.available--;
1921
1922	spin_unlock_irq(&dlfb->urbs.lock);
1923
1924	unode = list_entry(entry, struct urb_node, entry);
1925	return unode->urb;
1926}
1927
1928static int dlfb_submit_urb(struct dlfb_data *dlfb, struct urb *urb, size_t len)
1929{
1930	int ret;
1931
1932	BUG_ON(len > dlfb->urbs.size);
1933
1934	urb->transfer_buffer_length = len; /* set to actual payload len */
1935	ret = usb_submit_urb(urb, GFP_KERNEL);
1936	if (ret) {
1937		dlfb_urb_completion(urb); /* because no one else will */
1938		atomic_set(&dlfb->lost_pixels, 1);
1939		dev_err(&dlfb->udev->dev, "submit urb error: %d\n", ret);
1940	}
1941	return ret;
1942}
1943
1944module_param(console, bool, S_IWUSR | S_IRUSR | S_IWGRP | S_IRGRP);
1945MODULE_PARM_DESC(console, "Allow fbcon to open framebuffer");
1946
1947module_param(fb_defio, bool, S_IWUSR | S_IRUSR | S_IWGRP | S_IRGRP);
1948MODULE_PARM_DESC(fb_defio, "Page fault detection of mmap writes");
1949
1950module_param(shadow, bool, S_IWUSR | S_IRUSR | S_IWGRP | S_IRGRP);
1951MODULE_PARM_DESC(shadow, "Shadow vid mem. Disable to save mem but lose perf");
1952
1953module_param(pixel_limit, int, S_IWUSR | S_IRUSR | S_IWGRP | S_IRGRP);
1954MODULE_PARM_DESC(pixel_limit, "Force limit on max mode (in x*y pixels)");
1955
1956MODULE_AUTHOR("Roberto De Ioris <roberto@unbit.it>, "
1957	      "Jaya Kumar <jayakumar.lkml@gmail.com>, "
1958	      "Bernie Thompson <bernie@plugable.com>");
1959MODULE_DESCRIPTION("DisplayLink kernel framebuffer driver");
1960MODULE_LICENSE("GPL");
1961