drivers/gpu/drm/udl/udl_modeset.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Copyright (C) 2012 Red Hat
   4  *
   5  * based in parts on udlfb.c:
   6  * Copyright (C) 2009 Roberto De Ioris <roberto@unbit.it>
   7  * Copyright (C) 2009 Jaya Kumar <jayakumar.lkml@gmail.com>
   8  * Copyright (C) 2009 Bernie Thompson <bernie@plugable.com>
   9  */
  10
  11 #include <linux/bitfield.h>
  12
  13 #include <drm/drm_atomic.h>
  14 #include <drm/drm_atomic_helper.h>
  15 #include <drm/drm_crtc_helper.h>
  16 #include <drm/drm_damage_helper.h>
  17 #include <drm/drm_drv.h>
  18 #include <drm/drm_edid.h>
  19 #include <drm/drm_fourcc.h>
  20 #include <drm/drm_gem_atomic_helper.h>
  21 #include <drm/drm_gem_framebuffer_helper.h>
  22 #include <drm/drm_gem_shmem_helper.h>
  23 #include <drm/drm_modeset_helper_vtables.h>
  24 #include <drm/drm_plane_helper.h>
  25 #include <drm/drm_probe_helper.h>
  26 #include <drm/drm_vblank.h>
  27
  28 #include "udl_drv.h"
  29 #include "udl_proto.h"
  30
  31 /*
  32  * All DisplayLink bulk operations start with 0xaf (UDL_MSG_BULK), followed by
  33  * a specific command code. All operations are written to a command buffer, which
  34  * the driver sends to the device.
  35  */
  36 static char *udl_set_register(char *buf, u8 reg, u8 val)
  37 {
  38         *buf++ = UDL_MSG_BULK;
  39         *buf++ = UDL_CMD_WRITEREG;
  40         *buf++ = reg;
  41         *buf++ = val;
  42
  43         return buf;
  44 }
  45
  46 static char *udl_vidreg_lock(char *buf)
  47 {
  48         return udl_set_register(buf, UDL_REG_VIDREG, UDL_VIDREG_LOCK);
  49 }
  50
  51 static char *udl_vidreg_unlock(char *buf)
  52 {
  53         return udl_set_register(buf, UDL_REG_VIDREG, UDL_VIDREG_UNLOCK);
  54 }
  55
  56 static char *udl_set_blank_mode(char *buf, u8 mode)
  57 {
  58         return udl_set_register(buf, UDL_REG_BLANKMODE, mode);
  59 }
  60
  61 static char *udl_set_color_depth(char *buf, u8 selection)
  62 {
  63         return udl_set_register(buf, UDL_REG_COLORDEPTH, selection);
  64 }
  65
  66 static char *udl_set_base16bpp(char *buf, u32 base)
  67 {
  68         /* the base pointer is 24 bits wide, 0x20 is hi byte. */
  69         u8 reg20 = FIELD_GET(UDL_BASE_ADDR2_MASK, base);
  70         u8 reg21 = FIELD_GET(UDL_BASE_ADDR1_MASK, base);
  71         u8 reg22 = FIELD_GET(UDL_BASE_ADDR0_MASK, base);
  72
  73         buf = udl_set_register(buf, UDL_REG_BASE16BPP_ADDR2, reg20);
  74         buf = udl_set_register(buf, UDL_REG_BASE16BPP_ADDR1, reg21);
  75         buf = udl_set_register(buf, UDL_REG_BASE16BPP_ADDR0, reg22);
  76
  77         return buf;
  78 }
  79
  80 /*
  81  * DisplayLink HW has separate 16bpp and 8bpp framebuffers.
  82  * In 24bpp modes, the low 323 RGB bits go in the 8bpp framebuffer
  83  */
  84 static char *udl_set_base8bpp(char *buf, u32 base)
  85 {
  86         /* the base pointer is 24 bits wide, 0x26 is hi byte. */
  87         u8 reg26 = FIELD_GET(UDL_BASE_ADDR2_MASK, base);
  88         u8 reg27 = FIELD_GET(UDL_BASE_ADDR1_MASK, base);
  89         u8 reg28 = FIELD_GET(UDL_BASE_ADDR0_MASK, base);
  90
  91         buf = udl_set_register(buf, UDL_REG_BASE8BPP_ADDR2, reg26);
  92         buf = udl_set_register(buf, UDL_REG_BASE8BPP_ADDR1, reg27);
  93         buf = udl_set_register(buf, UDL_REG_BASE8BPP_ADDR0, reg28);
  94
  95         return buf;
  96 }
  97
  98 static char *udl_set_register_16(char *wrptr, u8 reg, u16 value)
  99 {
 100         wrptr = udl_set_register(wrptr, reg, value >> 8);
 101         return udl_set_register(wrptr, reg+1, value);
 102 }
 103
 104 /*
 105  * This is kind of weird because the controller takes some
 106  * register values in a different byte order than other registers.
 107  */
 108 static char *udl_set_register_16be(char *wrptr, u8 reg, u16 value)
 109 {
 110         wrptr = udl_set_register(wrptr, reg, value);
 111         return udl_set_register(wrptr, reg+1, value >> 8);
 112 }
 113
 114 /*
 115  * LFSR is linear feedback shift register. The reason we have this is
 116  * because the display controller needs to minimize the clock depth of
 117  * various counters used in the display path. So this code reverses the
 118  * provided value into the lfsr16 value by counting backwards to get
 119  * the value that needs to be set in the hardware comparator to get the
 120  * same actual count. This makes sense once you read above a couple of
 121  * times and think about it from a hardware perspective.
 122  */
 123 static u16 udl_lfsr16(u16 actual_count)
 124 {
 125         u32 lv = 0xFFFF; /* This is the lfsr value that the hw starts with */
 126
 127         while (actual_count--) {
 128                 lv =     ((lv << 1) |
 129                         (((lv >> 15) ^ (lv >> 4) ^ (lv >> 2) ^ (lv >> 1)) & 1))
 130                         & 0xFFFF;
 131         }
 132
 133         return (u16) lv;
 134 }
 135
 136 /*
 137  * This does LFSR conversion on the value that is to be written.
 138  * See LFSR explanation above for more detail.
 139  */
 140 static char *udl_set_register_lfsr16(char *wrptr, u8 reg, u16 value)
 141 {
 142         return udl_set_register_16(wrptr, reg, udl_lfsr16(value));
 143 }
 144
 145 /*
 146  * Takes a DRM display mode and converts it into the DisplayLink
 147  * equivalent register commands.
 148  */
 149 static char *udl_set_display_mode(char *buf, struct drm_display_mode *mode)
 150 {
 151         u16 reg01 = mode->crtc_htotal - mode->crtc_hsync_start;
 152         u16 reg03 = reg01 + mode->crtc_hdisplay;
 153         u16 reg05 = mode->crtc_vtotal - mode->crtc_vsync_start;
 154         u16 reg07 = reg05 + mode->crtc_vdisplay;
 155         u16 reg09 = mode->crtc_htotal - 1;
 156         u16 reg0b = 1; /* libdlo hardcodes hsync start to 1 */
 157         u16 reg0d = mode->crtc_hsync_end - mode->crtc_hsync_start + 1;
 158         u16 reg0f = mode->hdisplay;
 159         u16 reg11 = mode->crtc_vtotal;
 160         u16 reg13 = 0; /* libdlo hardcodes vsync start to 0 */
 161         u16 reg15 = mode->crtc_vsync_end - mode->crtc_vsync_start;
 162         u16 reg17 = mode->crtc_vdisplay;
 163         u16 reg1b = mode->clock / 5;
 164
 165         buf = udl_set_register_lfsr16(buf, UDL_REG_XDISPLAYSTART, reg01);
 166         buf = udl_set_register_lfsr16(buf, UDL_REG_XDISPLAYEND, reg03);
 167         buf = udl_set_register_lfsr16(buf, UDL_REG_YDISPLAYSTART, reg05);
 168         buf = udl_set_register_lfsr16(buf, UDL_REG_YDISPLAYEND, reg07);
 169         buf = udl_set_register_lfsr16(buf, UDL_REG_XENDCOUNT, reg09);
 170         buf = udl_set_register_lfsr16(buf, UDL_REG_HSYNCSTART, reg0b);
 171         buf = udl_set_register_lfsr16(buf, UDL_REG_HSYNCEND, reg0d);
 172         buf = udl_set_register_16(buf, UDL_REG_HPIXELS, reg0f);
 173         buf = udl_set_register_lfsr16(buf, UDL_REG_YENDCOUNT, reg11);
 174         buf = udl_set_register_lfsr16(buf, UDL_REG_VSYNCSTART, reg13);
 175         buf = udl_set_register_lfsr16(buf, UDL_REG_VSYNCEND, reg15);
 176         buf = udl_set_register_16(buf, UDL_REG_VPIXELS, reg17);
 177         buf = udl_set_register_16be(buf, UDL_REG_PIXELCLOCK5KHZ, reg1b);
 178
 179         return buf;
 180 }
 181
 182 static char *udl_dummy_render(char *wrptr)
 183 {
 184         *wrptr++ = UDL_MSG_BULK;
 185         *wrptr++ = UDL_CMD_WRITECOPY16;
 186         *wrptr++ = 0x00; /* from addr */
 187         *wrptr++ = 0x00;
 188         *wrptr++ = 0x00;
 189         *wrptr++ = 0x01; /* one pixel */
 190         *wrptr++ = 0x00; /* to address */
 191         *wrptr++ = 0x00;
 192         *wrptr++ = 0x00;
 193         return wrptr;
 194 }
 195
 196 static long udl_log_cpp(unsigned int cpp)
 197 {
 198         if (WARN_ON(!is_power_of_2(cpp)))
 199                 return -EINVAL;
 200         return __ffs(cpp);
 201 }
 202
 203 static int udl_handle_damage(struct drm_framebuffer *fb,
 204                              const struct iosys_map *map,
 205                              const struct drm_rect *clip)
 206 {
 207         struct drm_device *dev = fb->dev;
 208         void *vaddr = map->vaddr; /* TODO: Use mapping abstraction properly */
 209         int i, ret;
 210         char *cmd;
 211         struct urb *urb;
 212         int log_bpp;
 213
 214         ret = udl_log_cpp(fb->format->cpp[0]);
 215         if (ret < 0)
 216                 return ret;
 217         log_bpp = ret;
 218
 219         urb = udl_get_urb(dev);
 220         if (!urb)
 221                 return -ENOMEM;
 222         cmd = urb->transfer_buffer;
 223
 224         for (i = clip->y1; i < clip->y2; i++) {
 225                 const int line_offset = fb->pitches[0] * i;
 226                 const int byte_offset = line_offset + (clip->x1 << log_bpp);
 227                 const int dev_byte_offset = (fb->width * i + clip->x1) << log_bpp;
 228                 const int byte_width = drm_rect_width(clip) << log_bpp;
 229                 ret = udl_render_hline(dev, log_bpp, &urb, (char *)vaddr,
 230                                        &cmd, byte_offset, dev_byte_offset,
 231                                        byte_width);
 232                 if (ret)
 233                         return ret;
 234         }
 235
 236         if (cmd > (char *)urb->transfer_buffer) {
 237                 /* Send partial buffer remaining before exiting */
 238                 int len;
 239                 if (cmd < (char *)urb->transfer_buffer + urb->transfer_buffer_length)
 240                         *cmd++ = UDL_MSG_BULK;
 241                 len = cmd - (char *)urb->transfer_buffer;
 242                 ret = udl_submit_urb(dev, urb, len);
 243         } else {
 244                 udl_urb_completion(urb);
 245         }
 246
 247         return 0;
 248 }
 249
 250 /*
 251  * Primary plane
 252  */
 253
 254 static const uint32_t udl_primary_plane_formats[] = {
 255         DRM_FORMAT_RGB565,
 256         DRM_FORMAT_XRGB8888,
 257 };
 258
 259 static const uint64_t udl_primary_plane_fmtmods[] = {
 260         DRM_FORMAT_MOD_LINEAR,
 261         DRM_FORMAT_MOD_INVALID
 262 };
 263
 264 static void udl_primary_plane_helper_atomic_update(struct drm_plane *plane,
 265                                                    struct drm_atomic_state *state)
 266 {
 267         struct drm_device *dev = plane->dev;
 268         struct drm_plane_state *plane_state = drm_atomic_get_new_plane_state(state, plane);
 269         struct drm_shadow_plane_state *shadow_plane_state = to_drm_shadow_plane_state(plane_state);
 270         struct drm_framebuffer *fb = plane_state->fb;
 271         struct drm_plane_state *old_plane_state = drm_atomic_get_old_plane_state(state, plane);
 272         struct drm_atomic_helper_damage_iter iter;
 273         struct drm_rect damage;
 274         int ret, idx;
 275
 276         if (!fb)
 277                 return; /* no framebuffer; plane is disabled */
 278
 279         ret = drm_gem_fb_begin_cpu_access(fb, DMA_FROM_DEVICE);
 280         if (ret)
 281                 return;
 282
 283         if (!drm_dev_enter(dev, &idx))
 284                 goto out_drm_gem_fb_end_cpu_access;
 285
 286         drm_atomic_helper_damage_iter_init(&iter, old_plane_state, plane_state);
 287         drm_atomic_for_each_plane_damage(&iter, &damage) {
 288                 udl_handle_damage(fb, &shadow_plane_state->data[0], &damage);
 289         }
 290
 291         drm_dev_exit(idx);
 292
 293 out_drm_gem_fb_end_cpu_access:
 294         drm_gem_fb_end_cpu_access(fb, DMA_FROM_DEVICE);
 295 }
 296
 297 static const struct drm_plane_helper_funcs udl_primary_plane_helper_funcs = {
 298         DRM_GEM_SHADOW_PLANE_HELPER_FUNCS,
 299         .atomic_check = drm_plane_helper_atomic_check,
 300         .atomic_update = udl_primary_plane_helper_atomic_update,
 301 };
 302
 303 static const struct drm_plane_funcs udl_primary_plane_funcs = {
 304         .update_plane = drm_atomic_helper_update_plane,
 305         .disable_plane = drm_atomic_helper_disable_plane,
 306         .destroy = drm_plane_cleanup,
 307         DRM_GEM_SHADOW_PLANE_FUNCS,
 308 };
 309
 310 /*
 311  * CRTC
 312  */
 313
 314 static void udl_crtc_helper_atomic_enable(struct drm_crtc *crtc, struct drm_atomic_state *state)
 315 {
 316         struct drm_device *dev = crtc->dev;
 317         struct drm_crtc_state *crtc_state = drm_atomic_get_new_crtc_state(state, crtc);
 318         struct drm_display_mode *mode = &crtc_state->mode;
 319         struct urb *urb;
 320         char *buf;
 321         int idx;
 322
 323         if (!drm_dev_enter(dev, &idx))
 324                 return;
 325
 326         urb = udl_get_urb(dev);
 327         if (!urb)
 328                 goto out;
 329
 330         buf = (char *)urb->transfer_buffer;
 331         buf = udl_vidreg_lock(buf);
 332         buf = udl_set_color_depth(buf, UDL_COLORDEPTH_16BPP);
 333         /* set base for 16bpp segment to 0 */
 334         buf = udl_set_base16bpp(buf, 0);
 335         /* set base for 8bpp segment to end of fb */
 336         buf = udl_set_base8bpp(buf, 2 * mode->vdisplay * mode->hdisplay);
 337         buf = udl_set_display_mode(buf, mode);
 338         buf = udl_set_blank_mode(buf, UDL_BLANKMODE_ON);
 339         buf = udl_vidreg_unlock(buf);
 340         buf = udl_dummy_render(buf);
 341
 342         udl_submit_urb(dev, urb, buf - (char *)urb->transfer_buffer);
 343
 344 out:
 345         drm_dev_exit(idx);
 346 }
 347
 348 static void udl_crtc_helper_atomic_disable(struct drm_crtc *crtc, struct drm_atomic_state *state)
 349 {
 350         struct drm_device *dev = crtc->dev;
 351         struct urb *urb;
 352         char *buf;
 353         int idx;
 354
 355         if (!drm_dev_enter(dev, &idx))
 356                 return;
 357
 358         urb = udl_get_urb(dev);
 359         if (!urb)
 360                 goto out;
 361
 362         buf = (char *)urb->transfer_buffer;
 363         buf = udl_vidreg_lock(buf);
 364         buf = udl_set_blank_mode(buf, UDL_BLANKMODE_POWERDOWN);
 365         buf = udl_vidreg_unlock(buf);
 366         buf = udl_dummy_render(buf);
 367
 368         udl_submit_urb(dev, urb, buf - (char *)urb->transfer_buffer);
 369
 370 out:
 371         drm_dev_exit(idx);
 372 }
 373
 374 static const struct drm_crtc_helper_funcs udl_crtc_helper_funcs = {
 375         .atomic_check = drm_crtc_helper_atomic_check,
 376         .atomic_enable = udl_crtc_helper_atomic_enable,
 377         .atomic_disable = udl_crtc_helper_atomic_disable,
 378 };
 379
 380 static const struct drm_crtc_funcs udl_crtc_funcs = {
 381         .reset = drm_atomic_helper_crtc_reset,
 382         .destroy = drm_crtc_cleanup,
 383         .set_config = drm_atomic_helper_set_config,
 384         .page_flip = drm_atomic_helper_page_flip,
 385         .atomic_duplicate_state = drm_atomic_helper_crtc_duplicate_state,
 386         .atomic_destroy_state = drm_atomic_helper_crtc_destroy_state,
 387 };
 388
 389 /*
 390  * Encoder
 391  */
 392
 393 static const struct drm_encoder_funcs udl_encoder_funcs = {
 394         .destroy = drm_encoder_cleanup,
 395 };
 396
 397 /*
 398  * Connector
 399  */
 400
 401 static int udl_connector_helper_get_modes(struct drm_connector *connector)
 402 {
 403         struct udl_connector *udl_connector = to_udl_connector(connector);
 404
 405         drm_connector_update_edid_property(connector, udl_connector->edid);
 406         if (udl_connector->edid)
 407                 return drm_add_edid_modes(connector, udl_connector->edid);
 408
 409         return 0;
 410 }
 411
 412 static const struct drm_connector_helper_funcs udl_connector_helper_funcs = {
 413         .get_modes = udl_connector_helper_get_modes,
 414 };
 415
 416 static int udl_get_edid_block(void *data, u8 *buf, unsigned int block, size_t len)
 417 {
 418         struct udl_device *udl = data;
 419         struct drm_device *dev = &udl->drm;
 420         struct usb_device *udev = udl_to_usb_device(udl);
 421         u8 *read_buff;
 422         int ret;
 423         size_t i;
 424
 425         read_buff = kmalloc(2, GFP_KERNEL);
 426         if (!read_buff)
 427                 return -ENOMEM;
 428
 429         for (i = 0; i < len; i++) {
 430                 int bval = (i + block * EDID_LENGTH) << 8;
 431
 432                 ret = usb_control_msg(udev, usb_rcvctrlpipe(udev, 0),
 433                                       0x02, (0x80 | (0x02 << 5)), bval,
 434                                       0xA1, read_buff, 2, USB_CTRL_GET_TIMEOUT);
 435                 if (ret < 0) {
 436                         drm_err(dev, "Read EDID byte %zu failed err %x\n", i, ret);
 437                         goto err_kfree;
 438                 } else if (ret < 1) {
 439                         ret = -EIO;
 440                         drm_err(dev, "Read EDID byte %zu failed\n", i);
 441                         goto err_kfree;
 442                 }
 443
 444                 buf[i] = read_buff[1];
 445         }
 446
 447         kfree(read_buff);
 448
 449         return 0;
 450
 451 err_kfree:
 452         kfree(read_buff);
 453         return ret;
 454 }
 455
 456 static enum drm_connector_status udl_connector_detect(struct drm_connector *connector, bool force)
 457 {
 458         struct drm_device *dev = connector->dev;
 459         struct udl_device *udl = to_udl(dev);
 460         struct udl_connector *udl_connector = to_udl_connector(connector);
 461         enum drm_connector_status status = connector_status_disconnected;
 462         int idx;
 463
 464         /* cleanup previous EDID */
 465         kfree(udl_connector->edid);
 466         udl_connector->edid = NULL;
 467
 468         if (!drm_dev_enter(dev, &idx))
 469                 return connector_status_disconnected;
 470
 471         udl_connector->edid = drm_do_get_edid(connector, udl_get_edid_block, udl);
 472         if (udl_connector->edid)
 473                 status = connector_status_connected;
 474
 475         drm_dev_exit(idx);
 476
 477         return status;
 478 }
 479
 480 static void udl_connector_destroy(struct drm_connector *connector)
 481 {
 482         struct udl_connector *udl_connector = to_udl_connector(connector);
 483
 484         drm_connector_cleanup(connector);
 485         kfree(udl_connector->edid);
 486         kfree(udl_connector);
 487 }
 488
 489 static const struct drm_connector_funcs udl_connector_funcs = {
 490         .reset = drm_atomic_helper_connector_reset,
 491         .detect = udl_connector_detect,
 492         .fill_modes = drm_helper_probe_single_connector_modes,
 493         .destroy = udl_connector_destroy,
 494         .atomic_duplicate_state = drm_atomic_helper_connector_duplicate_state,
 495         .atomic_destroy_state = drm_atomic_helper_connector_destroy_state,
 496 };
 497
 498 struct drm_connector *udl_connector_init(struct drm_device *dev)
 499 {
 500         struct udl_connector *udl_connector;
 501         struct drm_connector *connector;
 502         int ret;
 503
 504         udl_connector = kzalloc(sizeof(*udl_connector), GFP_KERNEL);
 505         if (!udl_connector)
 506                 return ERR_PTR(-ENOMEM);
 507
 508         connector = &udl_connector->connector;
 509         ret = drm_connector_init(dev, connector, &udl_connector_funcs, DRM_MODE_CONNECTOR_VGA);
 510         if (ret)
 511                 goto err_kfree;
 512
 513         drm_connector_helper_add(connector, &udl_connector_helper_funcs);
 514
 515         connector->polled = DRM_CONNECTOR_POLL_HPD |
 516                             DRM_CONNECTOR_POLL_CONNECT |
 517                             DRM_CONNECTOR_POLL_DISCONNECT;
 518
 519         return connector;
 520
 521 err_kfree:
 522         kfree(udl_connector);
 523         return ERR_PTR(ret);
 524 }
 525
 526 /*
 527  * Modesetting
 528  */
 529
 530 static enum drm_mode_status udl_mode_config_mode_valid(struct drm_device *dev,
 531                                                        const struct drm_display_mode *mode)
 532 {
 533         struct udl_device *udl = to_udl(dev);
 534
 535         if (udl->sku_pixel_limit) {
 536                 if (mode->vdisplay * mode->hdisplay > udl->sku_pixel_limit)
 537                         return MODE_MEM;
 538         }
 539
 540         return MODE_OK;
 541 }
 542
 543 static const struct drm_mode_config_funcs udl_mode_config_funcs = {
 544         .fb_create = drm_gem_fb_create_with_dirty,
 545         .mode_valid = udl_mode_config_mode_valid,
 546         .atomic_check  = drm_atomic_helper_check,
 547         .atomic_commit = drm_atomic_helper_commit,
 548 };
 549
 550 int udl_modeset_init(struct drm_device *dev)
 551 {
 552         struct udl_device *udl = to_udl(dev);
 553         struct drm_plane *primary_plane;
 554         struct drm_crtc *crtc;
 555         struct drm_encoder *encoder;
 556         struct drm_connector *connector;
 557         int ret;
 558
 559         ret = drmm_mode_config_init(dev);
 560         if (ret)
 561                 return ret;
 562
 563         dev->mode_config.min_width = 640;
 564         dev->mode_config.min_height = 480;
 565         dev->mode_config.max_width = 2048;
 566         dev->mode_config.max_height = 2048;
 567         dev->mode_config.preferred_depth = 16;
 568         dev->mode_config.funcs = &udl_mode_config_funcs;
 569
 570         primary_plane = &udl->primary_plane;
 571         ret = drm_universal_plane_init(dev, primary_plane, 0,
 572                                        &udl_primary_plane_funcs,
 573                                        udl_primary_plane_formats,
 574                                        ARRAY_SIZE(udl_primary_plane_formats),
 575                                        udl_primary_plane_fmtmods,
 576                                        DRM_PLANE_TYPE_PRIMARY, NULL);
 577         if (ret)
 578                 return ret;
 579         drm_plane_helper_add(primary_plane, &udl_primary_plane_helper_funcs);
 580         drm_plane_enable_fb_damage_clips(primary_plane);
 581
 582         crtc = &udl->crtc;
 583         ret = drm_crtc_init_with_planes(dev, crtc, primary_plane, NULL,
 584                                         &udl_crtc_funcs, NULL);
 585         if (ret)
 586                 return ret;
 587         drm_crtc_helper_add(crtc, &udl_crtc_helper_funcs);
 588
 589         encoder = &udl->encoder;
 590         ret = drm_encoder_init(dev, encoder, &udl_encoder_funcs, DRM_MODE_ENCODER_DAC, NULL);
 591         if (ret)
 592                 return ret;
 593         encoder->possible_crtcs = drm_crtc_mask(crtc);
 594
 595         connector = udl_connector_init(dev);
 596         if (IS_ERR(connector))
 597                 return PTR_ERR(connector);
 598         ret = drm_connector_attach_encoder(connector, encoder);
 599         if (ret)
 600                 return ret;
 601
 602         drm_mode_config_reset(dev);
 603
 604         return 0;
 605 }