1/* 2 * Copyright © 2009 Keith Packard 3 * 4 * Permission to use, copy, modify, distribute, and sell this software and its 5 * documentation for any purpose is hereby granted without fee, provided that 6 * the above copyright notice appear in all copies and that both that copyright 7 * notice and this permission notice appear in supporting documentation, and 8 * that the name of the copyright holders not be used in advertising or 9 * publicity pertaining to distribution of the software without specific, 10 * written prior permission. The copyright holders make no representations 11 * about the suitability of this software for any purpose. It is provided "as 12 * is" without express or implied warranty. 13 * 14 * THE COPYRIGHT HOLDERS DISCLAIM ALL WARRANTIES WITH REGARD TO THIS SOFTWARE, 15 * INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO 16 * EVENT SHALL THE COPYRIGHT HOLDERS BE LIABLE FOR ANY SPECIAL, INDIRECT OR 17 * CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, 18 * DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER 19 * TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE 20 * OF THIS SOFTWARE. 21 */ 22 23#include <linux/kernel.h> 24#include <linux/module.h> 25#include <linux/delay.h> 26#include <linux/init.h> 27#include <linux/errno.h> 28#include <linux/sched.h> 29#include <linux/i2c.h> 30#include <drm/drm_dp_helper.h> 31#include <drm/drmP.h> 32 33/** 34 * DOC: dp helpers 35 * 36 * These functions contain some common logic and helpers at various abstraction 37 * levels to deal with Display Port sink devices and related things like DP aux 38 * channel transfers, EDID reading over DP aux channels, decoding certain DPCD 39 * blocks, ... 40 */ 41 42/* Helpers for DP link training */ 43static u8 dp_link_status(const u8 link_status[DP_LINK_STATUS_SIZE], int r) 44{ 45 return link_status[r - DP_LANE0_1_STATUS]; 46} 47 48static u8 dp_get_lane_status(const u8 link_status[DP_LINK_STATUS_SIZE], 49 int lane) 50{ 51 int i = DP_LANE0_1_STATUS + (lane >> 1); 52 int s = (lane & 1) * 4; 53 u8 l = dp_link_status(link_status, i); 54 return (l >> s) & 0xf; 55} 56 57bool drm_dp_channel_eq_ok(const u8 link_status[DP_LINK_STATUS_SIZE], 58 int lane_count) 59{ 60 u8 lane_align; 61 u8 lane_status; 62 int lane; 63 64 lane_align = dp_link_status(link_status, 65 DP_LANE_ALIGN_STATUS_UPDATED); 66 if ((lane_align & DP_INTERLANE_ALIGN_DONE) == 0) 67 return false; 68 for (lane = 0; lane < lane_count; lane++) { 69 lane_status = dp_get_lane_status(link_status, lane); 70 if ((lane_status & DP_CHANNEL_EQ_BITS) != DP_CHANNEL_EQ_BITS) 71 return false; 72 } 73 return true; 74} 75EXPORT_SYMBOL(drm_dp_channel_eq_ok); 76 77bool drm_dp_clock_recovery_ok(const u8 link_status[DP_LINK_STATUS_SIZE], 78 int lane_count) 79{ 80 int lane; 81 u8 lane_status; 82 83 for (lane = 0; lane < lane_count; lane++) { 84 lane_status = dp_get_lane_status(link_status, lane); 85 if ((lane_status & DP_LANE_CR_DONE) == 0) 86 return false; 87 } 88 return true; 89} 90EXPORT_SYMBOL(drm_dp_clock_recovery_ok); 91 92u8 drm_dp_get_adjust_request_voltage(const u8 link_status[DP_LINK_STATUS_SIZE], 93 int lane) 94{ 95 int i = DP_ADJUST_REQUEST_LANE0_1 + (lane >> 1); 96 int s = ((lane & 1) ? 97 DP_ADJUST_VOLTAGE_SWING_LANE1_SHIFT : 98 DP_ADJUST_VOLTAGE_SWING_LANE0_SHIFT); 99 u8 l = dp_link_status(link_status, i); 100 101 return ((l >> s) & 0x3) << DP_TRAIN_VOLTAGE_SWING_SHIFT; 102} 103EXPORT_SYMBOL(drm_dp_get_adjust_request_voltage); 104 105u8 drm_dp_get_adjust_request_pre_emphasis(const u8 link_status[DP_LINK_STATUS_SIZE], 106 int lane) 107{ 108 int i = DP_ADJUST_REQUEST_LANE0_1 + (lane >> 1); 109 int s = ((lane & 1) ? 110 DP_ADJUST_PRE_EMPHASIS_LANE1_SHIFT : 111 DP_ADJUST_PRE_EMPHASIS_LANE0_SHIFT); 112 u8 l = dp_link_status(link_status, i); 113 114 return ((l >> s) & 0x3) << DP_TRAIN_PRE_EMPHASIS_SHIFT; 115} 116EXPORT_SYMBOL(drm_dp_get_adjust_request_pre_emphasis); 117 118void drm_dp_link_train_clock_recovery_delay(const u8 dpcd[DP_RECEIVER_CAP_SIZE]) { 119 if (dpcd[DP_TRAINING_AUX_RD_INTERVAL] == 0) 120 udelay(100); 121 else 122 mdelay(dpcd[DP_TRAINING_AUX_RD_INTERVAL] * 4); 123} 124EXPORT_SYMBOL(drm_dp_link_train_clock_recovery_delay); 125 126void drm_dp_link_train_channel_eq_delay(const u8 dpcd[DP_RECEIVER_CAP_SIZE]) { 127 if (dpcd[DP_TRAINING_AUX_RD_INTERVAL] == 0) 128 udelay(400); 129 else 130 mdelay(dpcd[DP_TRAINING_AUX_RD_INTERVAL] * 4); 131} 132EXPORT_SYMBOL(drm_dp_link_train_channel_eq_delay); 133 134u8 drm_dp_link_rate_to_bw_code(int link_rate) 135{ 136 switch (link_rate) { 137 case 162000: 138 default: 139 return DP_LINK_BW_1_62; 140 case 270000: 141 return DP_LINK_BW_2_7; 142 case 540000: 143 return DP_LINK_BW_5_4; 144 } 145} 146EXPORT_SYMBOL(drm_dp_link_rate_to_bw_code); 147 148int drm_dp_bw_code_to_link_rate(u8 link_bw) 149{ 150 switch (link_bw) { 151 case DP_LINK_BW_1_62: 152 default: 153 return 162000; 154 case DP_LINK_BW_2_7: 155 return 270000; 156 case DP_LINK_BW_5_4: 157 return 540000; 158 } 159} 160EXPORT_SYMBOL(drm_dp_bw_code_to_link_rate); 161 162/** 163 * DOC: dp helpers 164 * 165 * The DisplayPort AUX channel is an abstraction to allow generic, driver- 166 * independent access to AUX functionality. Drivers can take advantage of 167 * this by filling in the fields of the drm_dp_aux structure. 168 * 169 * Transactions are described using a hardware-independent drm_dp_aux_msg 170 * structure, which is passed into a driver's .transfer() implementation. 171 * Both native and I2C-over-AUX transactions are supported. 172 */ 173 174static int drm_dp_dpcd_access(struct drm_dp_aux *aux, u8 request, 175 unsigned int offset, void *buffer, size_t size) 176{ 177 struct drm_dp_aux_msg msg; 178 unsigned int retry; 179 int err; 180 181 memset(&msg, 0, sizeof(msg)); 182 msg.address = offset; 183 msg.request = request; 184 msg.buffer = buffer; 185 msg.size = size; 186 187 /* 188 * The specification doesn't give any recommendation on how often to 189 * retry native transactions. We used to retry 7 times like for 190 * aux i2c transactions but real world devices this wasn't 191 * sufficient, bump to 32 which makes Dell 4k monitors happier. 192 */ 193 for (retry = 0; retry < 32; retry++) { 194 195 mutex_lock(&aux->hw_mutex); 196 err = aux->transfer(aux, &msg); 197 mutex_unlock(&aux->hw_mutex); 198 if (err < 0) { 199 if (err == -EBUSY) 200 continue; 201 202 return err; 203 } 204 205 206 switch (msg.reply & DP_AUX_NATIVE_REPLY_MASK) { 207 case DP_AUX_NATIVE_REPLY_ACK: 208 if (err < size) 209 return -EPROTO; 210 return err; 211 212 case DP_AUX_NATIVE_REPLY_NACK: 213 return -EIO; 214 215 case DP_AUX_NATIVE_REPLY_DEFER: 216 usleep_range(400, 500); 217 break; 218 } 219 } 220 221 DRM_DEBUG_KMS("too many retries, giving up\n"); 222 return -EIO; 223} 224 225/** 226 * drm_dp_dpcd_read() - read a series of bytes from the DPCD 227 * @aux: DisplayPort AUX channel 228 * @offset: address of the (first) register to read 229 * @buffer: buffer to store the register values 230 * @size: number of bytes in @buffer 231 * 232 * Returns the number of bytes transferred on success, or a negative error 233 * code on failure. -EIO is returned if the request was NAKed by the sink or 234 * if the retry count was exceeded. If not all bytes were transferred, this 235 * function returns -EPROTO. Errors from the underlying AUX channel transfer 236 * function, with the exception of -EBUSY (which causes the transaction to 237 * be retried), are propagated to the caller. 238 */ 239ssize_t drm_dp_dpcd_read(struct drm_dp_aux *aux, unsigned int offset, 240 void *buffer, size_t size) 241{ 242 return drm_dp_dpcd_access(aux, DP_AUX_NATIVE_READ, offset, buffer, 243 size); 244} 245EXPORT_SYMBOL(drm_dp_dpcd_read); 246 247/** 248 * drm_dp_dpcd_write() - write a series of bytes to the DPCD 249 * @aux: DisplayPort AUX channel 250 * @offset: address of the (first) register to write 251 * @buffer: buffer containing the values to write 252 * @size: number of bytes in @buffer 253 * 254 * Returns the number of bytes transferred on success, or a negative error 255 * code on failure. -EIO is returned if the request was NAKed by the sink or 256 * if the retry count was exceeded. If not all bytes were transferred, this 257 * function returns -EPROTO. Errors from the underlying AUX channel transfer 258 * function, with the exception of -EBUSY (which causes the transaction to 259 * be retried), are propagated to the caller. 260 */ 261ssize_t drm_dp_dpcd_write(struct drm_dp_aux *aux, unsigned int offset, 262 void *buffer, size_t size) 263{ 264 return drm_dp_dpcd_access(aux, DP_AUX_NATIVE_WRITE, offset, buffer, 265 size); 266} 267EXPORT_SYMBOL(drm_dp_dpcd_write); 268 269/** 270 * drm_dp_dpcd_read_link_status() - read DPCD link status (bytes 0x202-0x207) 271 * @aux: DisplayPort AUX channel 272 * @status: buffer to store the link status in (must be at least 6 bytes) 273 * 274 * Returns the number of bytes transferred on success or a negative error 275 * code on failure. 276 */ 277int drm_dp_dpcd_read_link_status(struct drm_dp_aux *aux, 278 u8 status[DP_LINK_STATUS_SIZE]) 279{ 280 return drm_dp_dpcd_read(aux, DP_LANE0_1_STATUS, status, 281 DP_LINK_STATUS_SIZE); 282} 283EXPORT_SYMBOL(drm_dp_dpcd_read_link_status); 284 285/** 286 * drm_dp_link_probe() - probe a DisplayPort link for capabilities 287 * @aux: DisplayPort AUX channel 288 * @link: pointer to structure in which to return link capabilities 289 * 290 * The structure filled in by this function can usually be passed directly 291 * into drm_dp_link_power_up() and drm_dp_link_configure() to power up and 292 * configure the link based on the link's capabilities. 293 * 294 * Returns 0 on success or a negative error code on failure. 295 */ 296int drm_dp_link_probe(struct drm_dp_aux *aux, struct drm_dp_link *link) 297{ 298 u8 values[3]; 299 int err; 300 301 memset(link, 0, sizeof(*link)); 302 303 err = drm_dp_dpcd_read(aux, DP_DPCD_REV, values, sizeof(values)); 304 if (err < 0) 305 return err; 306 307 link->revision = values[0]; 308 link->rate = drm_dp_bw_code_to_link_rate(values[1]); 309 link->num_lanes = values[2] & DP_MAX_LANE_COUNT_MASK; 310 311 if (values[2] & DP_ENHANCED_FRAME_CAP) 312 link->capabilities |= DP_LINK_CAP_ENHANCED_FRAMING; 313 314 return 0; 315} 316EXPORT_SYMBOL(drm_dp_link_probe); 317 318/** 319 * drm_dp_link_power_up() - power up a DisplayPort link 320 * @aux: DisplayPort AUX channel 321 * @link: pointer to a structure containing the link configuration 322 * 323 * Returns 0 on success or a negative error code on failure. 324 */ 325int drm_dp_link_power_up(struct drm_dp_aux *aux, struct drm_dp_link *link) 326{ 327 u8 value; 328 int err; 329 330 /* DP_SET_POWER register is only available on DPCD v1.1 and later */ 331 if (link->revision < 0x11) 332 return 0; 333 334 err = drm_dp_dpcd_readb(aux, DP_SET_POWER, &value); 335 if (err < 0) 336 return err; 337 338 value &= ~DP_SET_POWER_MASK; 339 value |= DP_SET_POWER_D0; 340 341 err = drm_dp_dpcd_writeb(aux, DP_SET_POWER, value); 342 if (err < 0) 343 return err; 344 345 /* 346 * According to the DP 1.1 specification, a "Sink Device must exit the 347 * power saving state within 1 ms" (Section 2.5.3.1, Table 5-52, "Sink 348 * Control Field" (register 0x600). 349 */ 350 usleep_range(1000, 2000); 351 352 return 0; 353} 354EXPORT_SYMBOL(drm_dp_link_power_up); 355 356/** 357 * drm_dp_link_power_down() - power down a DisplayPort link 358 * @aux: DisplayPort AUX channel 359 * @link: pointer to a structure containing the link configuration 360 * 361 * Returns 0 on success or a negative error code on failure. 362 */ 363int drm_dp_link_power_down(struct drm_dp_aux *aux, struct drm_dp_link *link) 364{ 365 u8 value; 366 int err; 367 368 /* DP_SET_POWER register is only available on DPCD v1.1 and later */ 369 if (link->revision < 0x11) 370 return 0; 371 372 err = drm_dp_dpcd_readb(aux, DP_SET_POWER, &value); 373 if (err < 0) 374 return err; 375 376 value &= ~DP_SET_POWER_MASK; 377 value |= DP_SET_POWER_D3; 378 379 err = drm_dp_dpcd_writeb(aux, DP_SET_POWER, value); 380 if (err < 0) 381 return err; 382 383 return 0; 384} 385EXPORT_SYMBOL(drm_dp_link_power_down); 386 387/** 388 * drm_dp_link_configure() - configure a DisplayPort link 389 * @aux: DisplayPort AUX channel 390 * @link: pointer to a structure containing the link configuration 391 * 392 * Returns 0 on success or a negative error code on failure. 393 */ 394int drm_dp_link_configure(struct drm_dp_aux *aux, struct drm_dp_link *link) 395{ 396 u8 values[2]; 397 int err; 398 399 values[0] = drm_dp_link_rate_to_bw_code(link->rate); 400 values[1] = link->num_lanes; 401 402 if (link->capabilities & DP_LINK_CAP_ENHANCED_FRAMING) 403 values[1] |= DP_LANE_COUNT_ENHANCED_FRAME_EN; 404 405 err = drm_dp_dpcd_write(aux, DP_LINK_BW_SET, values, sizeof(values)); 406 if (err < 0) 407 return err; 408 409 return 0; 410} 411EXPORT_SYMBOL(drm_dp_link_configure); 412 413/* 414 * I2C-over-AUX implementation 415 */ 416 417static u32 drm_dp_i2c_functionality(struct i2c_adapter *adapter) 418{ 419 return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL | 420 I2C_FUNC_SMBUS_READ_BLOCK_DATA | 421 I2C_FUNC_SMBUS_BLOCK_PROC_CALL | 422 I2C_FUNC_10BIT_ADDR; 423} 424 425/* 426 * Transfer a single I2C-over-AUX message and handle various error conditions, 427 * retrying the transaction as appropriate. It is assumed that the 428 * aux->transfer function does not modify anything in the msg other than the 429 * reply field. 430 * 431 * Returns bytes transferred on success, or a negative error code on failure. 432 */ 433static int drm_dp_i2c_do_msg(struct drm_dp_aux *aux, struct drm_dp_aux_msg *msg) 434{ 435 unsigned int retry; 436 int ret; 437 438 /* 439 * DP1.2 sections 2.7.7.1.5.6.1 and 2.7.7.1.6.6.1: A DP Source device 440 * is required to retry at least seven times upon receiving AUX_DEFER 441 * before giving up the AUX transaction. 442 */ 443 for (retry = 0; retry < 7; retry++) { 444 mutex_lock(&aux->hw_mutex); 445 ret = aux->transfer(aux, msg); 446 mutex_unlock(&aux->hw_mutex); 447 if (ret < 0) { 448 if (ret == -EBUSY) 449 continue; 450 451 DRM_DEBUG_KMS("transaction failed: %d\n", ret); 452 return ret; 453 } 454 455 456 switch (msg->reply & DP_AUX_NATIVE_REPLY_MASK) { 457 case DP_AUX_NATIVE_REPLY_ACK: 458 /* 459 * For I2C-over-AUX transactions this isn't enough, we 460 * need to check for the I2C ACK reply. 461 */ 462 break; 463 464 case DP_AUX_NATIVE_REPLY_NACK: 465 DRM_DEBUG_KMS("native nack (result=%d, size=%zu)\n", ret, msg->size); 466 return -EREMOTEIO; 467 468 case DP_AUX_NATIVE_REPLY_DEFER: 469 DRM_DEBUG_KMS("native defer"); 470 /* 471 * We could check for I2C bit rate capabilities and if 472 * available adjust this interval. We could also be 473 * more careful with DP-to-legacy adapters where a 474 * long legacy cable may force very low I2C bit rates. 475 * 476 * For now just defer for long enough to hopefully be 477 * safe for all use-cases. 478 */ 479 usleep_range(500, 600); 480 continue; 481 482 default: 483 DRM_ERROR("invalid native reply %#04x\n", msg->reply); 484 return -EREMOTEIO; 485 } 486 487 switch (msg->reply & DP_AUX_I2C_REPLY_MASK) { 488 case DP_AUX_I2C_REPLY_ACK: 489 /* 490 * Both native ACK and I2C ACK replies received. We 491 * can assume the transfer was successful. 492 */ 493 return ret; 494 495 case DP_AUX_I2C_REPLY_NACK: 496 DRM_DEBUG_KMS("I2C nack (result=%d, size=%zu\n", ret, msg->size); 497 aux->i2c_nack_count++; 498 return -EREMOTEIO; 499 500 case DP_AUX_I2C_REPLY_DEFER: 501 DRM_DEBUG_KMS("I2C defer\n"); 502 aux->i2c_defer_count++; 503 usleep_range(400, 500); 504 continue; 505 506 default: 507 DRM_ERROR("invalid I2C reply %#04x\n", msg->reply); 508 return -EREMOTEIO; 509 } 510 } 511 512 DRM_DEBUG_KMS("too many retries, giving up\n"); 513 return -EREMOTEIO; 514} 515 516/* 517 * Keep retrying drm_dp_i2c_do_msg until all data has been transferred. 518 * 519 * Returns an error code on failure, or a recommended transfer size on success. 520 */ 521static int drm_dp_i2c_drain_msg(struct drm_dp_aux *aux, struct drm_dp_aux_msg *orig_msg) 522{ 523 int err, ret = orig_msg->size; 524 struct drm_dp_aux_msg msg = *orig_msg; 525 526 while (msg.size > 0) { 527 err = drm_dp_i2c_do_msg(aux, &msg); 528 if (err <= 0) 529 return err == 0 ? -EPROTO : err; 530 531 if (err < msg.size && err < ret) { 532 DRM_DEBUG_KMS("Partial I2C reply: requested %zu bytes got %d bytes\n", 533 msg.size, err); 534 ret = err; 535 } 536 537 msg.size -= err; 538 msg.buffer += err; 539 } 540 541 return ret; 542} 543 544/* 545 * Bizlink designed DP->DVI-D Dual Link adapters require the I2C over AUX 546 * packets to be as large as possible. If not, the I2C transactions never 547 * succeed. Hence the default is maximum. 548 */ 549static int dp_aux_i2c_transfer_size __read_mostly = DP_AUX_MAX_PAYLOAD_BYTES; 550module_param_unsafe(dp_aux_i2c_transfer_size, int, 0644); 551MODULE_PARM_DESC(dp_aux_i2c_transfer_size, 552 "Number of bytes to transfer in a single I2C over DP AUX CH message, (1-16, default 16)"); 553 554static int drm_dp_i2c_xfer(struct i2c_adapter *adapter, struct i2c_msg *msgs, 555 int num) 556{ 557 struct drm_dp_aux *aux = adapter->algo_data; 558 unsigned int i, j; 559 unsigned transfer_size; 560 struct drm_dp_aux_msg msg; 561 int err = 0; 562 563 dp_aux_i2c_transfer_size = clamp(dp_aux_i2c_transfer_size, 1, DP_AUX_MAX_PAYLOAD_BYTES); 564 565 memset(&msg, 0, sizeof(msg)); 566 567 for (i = 0; i < num; i++) { 568 msg.address = msgs[i].addr; 569 msg.request = (msgs[i].flags & I2C_M_RD) ? 570 DP_AUX_I2C_READ : 571 DP_AUX_I2C_WRITE; 572 msg.request |= DP_AUX_I2C_MOT; 573 /* Send a bare address packet to start the transaction. 574 * Zero sized messages specify an address only (bare 575 * address) transaction. 576 */ 577 msg.buffer = NULL; 578 msg.size = 0; 579 err = drm_dp_i2c_do_msg(aux, &msg); 580 if (err < 0) 581 break; 582 /* We want each transaction to be as large as possible, but 583 * we'll go to smaller sizes if the hardware gives us a 584 * short reply. 585 */ 586 transfer_size = dp_aux_i2c_transfer_size; 587 for (j = 0; j < msgs[i].len; j += msg.size) { 588 msg.buffer = msgs[i].buf + j; 589 msg.size = min(transfer_size, msgs[i].len - j); 590 591 err = drm_dp_i2c_drain_msg(aux, &msg); 592 if (err < 0) 593 break; 594 transfer_size = err; 595 } 596 if (err < 0) 597 break; 598 } 599 if (err >= 0) 600 err = num; 601 /* Send a bare address packet to close out the transaction. 602 * Zero sized messages specify an address only (bare 603 * address) transaction. 604 */ 605 msg.request &= ~DP_AUX_I2C_MOT; 606 msg.buffer = NULL; 607 msg.size = 0; 608 (void)drm_dp_i2c_do_msg(aux, &msg); 609 610 return err; 611} 612 613static const struct i2c_algorithm drm_dp_i2c_algo = { 614 .functionality = drm_dp_i2c_functionality, 615 .master_xfer = drm_dp_i2c_xfer, 616}; 617 618/** 619 * drm_dp_aux_register() - initialise and register aux channel 620 * @aux: DisplayPort AUX channel 621 * 622 * Returns 0 on success or a negative error code on failure. 623 */ 624int drm_dp_aux_register(struct drm_dp_aux *aux) 625{ 626 mutex_init(&aux->hw_mutex); 627 628 aux->ddc.algo = &drm_dp_i2c_algo; 629 aux->ddc.algo_data = aux; 630 aux->ddc.retries = 3; 631 632 aux->ddc.class = I2C_CLASS_DDC; 633 aux->ddc.owner = THIS_MODULE; 634 aux->ddc.dev.parent = aux->dev; 635 aux->ddc.dev.of_node = aux->dev->of_node; 636 637 strlcpy(aux->ddc.name, aux->name ? aux->name : dev_name(aux->dev), 638 sizeof(aux->ddc.name)); 639 640 return i2c_add_adapter(&aux->ddc); 641} 642EXPORT_SYMBOL(drm_dp_aux_register); 643 644/** 645 * drm_dp_aux_unregister() - unregister an AUX adapter 646 * @aux: DisplayPort AUX channel 647 */ 648void drm_dp_aux_unregister(struct drm_dp_aux *aux) 649{ 650 i2c_del_adapter(&aux->ddc); 651} 652EXPORT_SYMBOL(drm_dp_aux_unregister); 653