2 * Copyright © 2009 Keith Packard
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.
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
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>
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
42 /* Helpers for DP link training */
43 static u8
dp_link_status(const u8 link_status
[DP_LINK_STATUS_SIZE
], int r
)
45 return link_status
[r
- DP_LANE0_1_STATUS
];
48 static u8
dp_get_lane_status(const u8 link_status
[DP_LINK_STATUS_SIZE
],
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;
57 bool drm_dp_channel_eq_ok(const u8 link_status
[DP_LINK_STATUS_SIZE
],
64 lane_align
= dp_link_status(link_status
,
65 DP_LANE_ALIGN_STATUS_UPDATED
);
66 if ((lane_align
& DP_INTERLANE_ALIGN_DONE
) == 0)
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
)
75 EXPORT_SYMBOL(drm_dp_channel_eq_ok
);
77 bool drm_dp_clock_recovery_ok(const u8 link_status
[DP_LINK_STATUS_SIZE
],
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)
90 EXPORT_SYMBOL(drm_dp_clock_recovery_ok
);
92 u8
drm_dp_get_adjust_request_voltage(const u8 link_status
[DP_LINK_STATUS_SIZE
],
95 int i
= DP_ADJUST_REQUEST_LANE0_1
+ (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
);
101 return ((l
>> s
) & 0x3) << DP_TRAIN_VOLTAGE_SWING_SHIFT
;
103 EXPORT_SYMBOL(drm_dp_get_adjust_request_voltage
);
105 u8
drm_dp_get_adjust_request_pre_emphasis(const u8 link_status
[DP_LINK_STATUS_SIZE
],
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
);
114 return ((l
>> s
) & 0x3) << DP_TRAIN_PRE_EMPHASIS_SHIFT
;
116 EXPORT_SYMBOL(drm_dp_get_adjust_request_pre_emphasis
);
118 void drm_dp_link_train_clock_recovery_delay(const u8 dpcd
[DP_RECEIVER_CAP_SIZE
]) {
119 if (dpcd
[DP_TRAINING_AUX_RD_INTERVAL
] == 0)
122 mdelay(dpcd
[DP_TRAINING_AUX_RD_INTERVAL
] * 4);
124 EXPORT_SYMBOL(drm_dp_link_train_clock_recovery_delay
);
126 void drm_dp_link_train_channel_eq_delay(const u8 dpcd
[DP_RECEIVER_CAP_SIZE
]) {
127 if (dpcd
[DP_TRAINING_AUX_RD_INTERVAL
] == 0)
130 mdelay(dpcd
[DP_TRAINING_AUX_RD_INTERVAL
] * 4);
132 EXPORT_SYMBOL(drm_dp_link_train_channel_eq_delay
);
134 u8
drm_dp_link_rate_to_bw_code(int link_rate
)
139 return DP_LINK_BW_1_62
;
141 return DP_LINK_BW_2_7
;
143 return DP_LINK_BW_5_4
;
146 EXPORT_SYMBOL(drm_dp_link_rate_to_bw_code
);
148 int drm_dp_bw_code_to_link_rate(u8 link_bw
)
151 case DP_LINK_BW_1_62
:
160 EXPORT_SYMBOL(drm_dp_bw_code_to_link_rate
);
162 #define AUX_RETRY_INTERVAL 500 /* us */
167 * The DisplayPort AUX channel is an abstraction to allow generic, driver-
168 * independent access to AUX functionality. Drivers can take advantage of
169 * this by filling in the fields of the drm_dp_aux structure.
171 * Transactions are described using a hardware-independent drm_dp_aux_msg
172 * structure, which is passed into a driver's .transfer() implementation.
173 * Both native and I2C-over-AUX transactions are supported.
176 static int drm_dp_dpcd_access(struct drm_dp_aux
*aux
, u8 request
,
177 unsigned int offset
, void *buffer
, size_t size
)
179 struct drm_dp_aux_msg msg
;
183 memset(&msg
, 0, sizeof(msg
));
184 msg
.address
= offset
;
185 msg
.request
= request
;
190 * The specification doesn't give any recommendation on how often to
191 * retry native transactions. We used to retry 7 times like for
192 * aux i2c transactions but real world devices this wasn't
193 * sufficient, bump to 32 which makes Dell 4k monitors happier.
195 for (retry
= 0; retry
< 32; retry
++) {
197 mutex_lock(&aux
->hw_mutex
);
198 err
= aux
->transfer(aux
, &msg
);
199 mutex_unlock(&aux
->hw_mutex
);
208 switch (msg
.reply
& DP_AUX_NATIVE_REPLY_MASK
) {
209 case DP_AUX_NATIVE_REPLY_ACK
:
214 case DP_AUX_NATIVE_REPLY_NACK
:
217 case DP_AUX_NATIVE_REPLY_DEFER
:
218 usleep_range(AUX_RETRY_INTERVAL
, AUX_RETRY_INTERVAL
+ 100);
223 DRM_DEBUG_KMS("too many retries, giving up\n");
228 * drm_dp_dpcd_read() - read a series of bytes from the DPCD
229 * @aux: DisplayPort AUX channel
230 * @offset: address of the (first) register to read
231 * @buffer: buffer to store the register values
232 * @size: number of bytes in @buffer
234 * Returns the number of bytes transferred on success, or a negative error
235 * code on failure. -EIO is returned if the request was NAKed by the sink or
236 * if the retry count was exceeded. If not all bytes were transferred, this
237 * function returns -EPROTO. Errors from the underlying AUX channel transfer
238 * function, with the exception of -EBUSY (which causes the transaction to
239 * be retried), are propagated to the caller.
241 ssize_t
drm_dp_dpcd_read(struct drm_dp_aux
*aux
, unsigned int offset
,
242 void *buffer
, size_t size
)
244 return drm_dp_dpcd_access(aux
, DP_AUX_NATIVE_READ
, offset
, buffer
,
247 EXPORT_SYMBOL(drm_dp_dpcd_read
);
250 * drm_dp_dpcd_write() - write a series of bytes to the DPCD
251 * @aux: DisplayPort AUX channel
252 * @offset: address of the (first) register to write
253 * @buffer: buffer containing the values to write
254 * @size: number of bytes in @buffer
256 * Returns the number of bytes transferred on success, or a negative error
257 * code on failure. -EIO is returned if the request was NAKed by the sink or
258 * if the retry count was exceeded. If not all bytes were transferred, this
259 * function returns -EPROTO. Errors from the underlying AUX channel transfer
260 * function, with the exception of -EBUSY (which causes the transaction to
261 * be retried), are propagated to the caller.
263 ssize_t
drm_dp_dpcd_write(struct drm_dp_aux
*aux
, unsigned int offset
,
264 void *buffer
, size_t size
)
266 return drm_dp_dpcd_access(aux
, DP_AUX_NATIVE_WRITE
, offset
, buffer
,
269 EXPORT_SYMBOL(drm_dp_dpcd_write
);
272 * drm_dp_dpcd_read_link_status() - read DPCD link status (bytes 0x202-0x207)
273 * @aux: DisplayPort AUX channel
274 * @status: buffer to store the link status in (must be at least 6 bytes)
276 * Returns the number of bytes transferred on success or a negative error
279 int drm_dp_dpcd_read_link_status(struct drm_dp_aux
*aux
,
280 u8 status
[DP_LINK_STATUS_SIZE
])
282 return drm_dp_dpcd_read(aux
, DP_LANE0_1_STATUS
, status
,
283 DP_LINK_STATUS_SIZE
);
285 EXPORT_SYMBOL(drm_dp_dpcd_read_link_status
);
288 * drm_dp_link_probe() - probe a DisplayPort link for capabilities
289 * @aux: DisplayPort AUX channel
290 * @link: pointer to structure in which to return link capabilities
292 * The structure filled in by this function can usually be passed directly
293 * into drm_dp_link_power_up() and drm_dp_link_configure() to power up and
294 * configure the link based on the link's capabilities.
296 * Returns 0 on success or a negative error code on failure.
298 int drm_dp_link_probe(struct drm_dp_aux
*aux
, struct drm_dp_link
*link
)
303 memset(link
, 0, sizeof(*link
));
305 err
= drm_dp_dpcd_read(aux
, DP_DPCD_REV
, values
, sizeof(values
));
309 link
->revision
= values
[0];
310 link
->rate
= drm_dp_bw_code_to_link_rate(values
[1]);
311 link
->num_lanes
= values
[2] & DP_MAX_LANE_COUNT_MASK
;
313 if (values
[2] & DP_ENHANCED_FRAME_CAP
)
314 link
->capabilities
|= DP_LINK_CAP_ENHANCED_FRAMING
;
318 EXPORT_SYMBOL(drm_dp_link_probe
);
321 * drm_dp_link_power_up() - power up a DisplayPort link
322 * @aux: DisplayPort AUX channel
323 * @link: pointer to a structure containing the link configuration
325 * Returns 0 on success or a negative error code on failure.
327 int drm_dp_link_power_up(struct drm_dp_aux
*aux
, struct drm_dp_link
*link
)
332 /* DP_SET_POWER register is only available on DPCD v1.1 and later */
333 if (link
->revision
< 0x11)
336 err
= drm_dp_dpcd_readb(aux
, DP_SET_POWER
, &value
);
340 value
&= ~DP_SET_POWER_MASK
;
341 value
|= DP_SET_POWER_D0
;
343 err
= drm_dp_dpcd_writeb(aux
, DP_SET_POWER
, value
);
348 * According to the DP 1.1 specification, a "Sink Device must exit the
349 * power saving state within 1 ms" (Section 2.5.3.1, Table 5-52, "Sink
350 * Control Field" (register 0x600).
352 usleep_range(1000, 2000);
356 EXPORT_SYMBOL(drm_dp_link_power_up
);
359 * drm_dp_link_power_down() - power down a DisplayPort link
360 * @aux: DisplayPort AUX channel
361 * @link: pointer to a structure containing the link configuration
363 * Returns 0 on success or a negative error code on failure.
365 int drm_dp_link_power_down(struct drm_dp_aux
*aux
, struct drm_dp_link
*link
)
370 /* DP_SET_POWER register is only available on DPCD v1.1 and later */
371 if (link
->revision
< 0x11)
374 err
= drm_dp_dpcd_readb(aux
, DP_SET_POWER
, &value
);
378 value
&= ~DP_SET_POWER_MASK
;
379 value
|= DP_SET_POWER_D3
;
381 err
= drm_dp_dpcd_writeb(aux
, DP_SET_POWER
, value
);
387 EXPORT_SYMBOL(drm_dp_link_power_down
);
390 * drm_dp_link_configure() - configure a DisplayPort link
391 * @aux: DisplayPort AUX channel
392 * @link: pointer to a structure containing the link configuration
394 * Returns 0 on success or a negative error code on failure.
396 int drm_dp_link_configure(struct drm_dp_aux
*aux
, struct drm_dp_link
*link
)
401 values
[0] = drm_dp_link_rate_to_bw_code(link
->rate
);
402 values
[1] = link
->num_lanes
;
404 if (link
->capabilities
& DP_LINK_CAP_ENHANCED_FRAMING
)
405 values
[1] |= DP_LANE_COUNT_ENHANCED_FRAME_EN
;
407 err
= drm_dp_dpcd_write(aux
, DP_LINK_BW_SET
, values
, sizeof(values
));
413 EXPORT_SYMBOL(drm_dp_link_configure
);
416 * I2C-over-AUX implementation
419 static u32
drm_dp_i2c_functionality(struct i2c_adapter
*adapter
)
421 return I2C_FUNC_I2C
| I2C_FUNC_SMBUS_EMUL
|
422 I2C_FUNC_SMBUS_READ_BLOCK_DATA
|
423 I2C_FUNC_SMBUS_BLOCK_PROC_CALL
|
427 #define AUX_PRECHARGE_LEN 10 /* 10 to 16 */
428 #define AUX_SYNC_LEN (16 + 4) /* preamble + AUX_SYNC_END */
429 #define AUX_STOP_LEN 4
430 #define AUX_CMD_LEN 4
431 #define AUX_ADDRESS_LEN 20
432 #define AUX_REPLY_PAD_LEN 4
433 #define AUX_LENGTH_LEN 8
436 * Calculate the duration of the AUX request/reply in usec. Gives the
437 * "best" case estimate, ie. successful while as short as possible.
439 static int drm_dp_aux_req_duration(const struct drm_dp_aux_msg
*msg
)
441 int len
= AUX_PRECHARGE_LEN
+ AUX_SYNC_LEN
+ AUX_STOP_LEN
+
442 AUX_CMD_LEN
+ AUX_ADDRESS_LEN
+ AUX_LENGTH_LEN
;
444 if ((msg
->request
& DP_AUX_I2C_READ
) == 0)
445 len
+= msg
->size
* 8;
450 static int drm_dp_aux_reply_duration(const struct drm_dp_aux_msg
*msg
)
452 int len
= AUX_PRECHARGE_LEN
+ AUX_SYNC_LEN
+ AUX_STOP_LEN
+
453 AUX_CMD_LEN
+ AUX_REPLY_PAD_LEN
;
456 * For read we expect what was asked. For writes there will
457 * be 0 or 1 data bytes. Assume 0 for the "best" case.
459 if (msg
->request
& DP_AUX_I2C_READ
)
460 len
+= msg
->size
* 8;
465 #define I2C_START_LEN 1
466 #define I2C_STOP_LEN 1
467 #define I2C_ADDR_LEN 9 /* ADDRESS + R/W + ACK/NACK */
468 #define I2C_DATA_LEN 9 /* DATA + ACK/NACK */
471 * Calculate the length of the i2c transfer in usec, assuming
472 * the i2c bus speed is as specified. Gives the the "worst"
473 * case estimate, ie. successful while as long as possible.
474 * Doesn't account the the "MOT" bit, and instead assumes each
475 * message includes a START, ADDRESS and STOP. Neither does it
476 * account for additional random variables such as clock stretching.
478 static int drm_dp_i2c_msg_duration(const struct drm_dp_aux_msg
*msg
,
481 /* AUX bitrate is 1MHz, i2c bitrate as specified */
482 return DIV_ROUND_UP((I2C_START_LEN
+ I2C_ADDR_LEN
+
483 msg
->size
* I2C_DATA_LEN
+
484 I2C_STOP_LEN
) * 1000, i2c_speed_khz
);
488 * Deterine how many retries should be attempted to successfully transfer
489 * the specified message, based on the estimated durations of the
490 * i2c and AUX transfers.
492 static int drm_dp_i2c_retry_count(const struct drm_dp_aux_msg
*msg
,
495 int aux_time_us
= drm_dp_aux_req_duration(msg
) +
496 drm_dp_aux_reply_duration(msg
);
497 int i2c_time_us
= drm_dp_i2c_msg_duration(msg
, i2c_speed_khz
);
499 return DIV_ROUND_UP(i2c_time_us
, aux_time_us
+ AUX_RETRY_INTERVAL
);
503 * FIXME currently assumes 10 kHz as some real world devices seem
504 * to require it. We should query/set the speed via DPCD if supported.
506 static int dp_aux_i2c_speed_khz __read_mostly
= 10;
507 module_param_unsafe(dp_aux_i2c_speed_khz
, int, 0644);
508 MODULE_PARM_DESC(dp_aux_i2c_speed_khz
,
509 "Assumed speed of the i2c bus in kHz, (1-400, default 10)");
512 * Transfer a single I2C-over-AUX message and handle various error conditions,
513 * retrying the transaction as appropriate. It is assumed that the
514 * aux->transfer function does not modify anything in the msg other than the
517 * Returns bytes transferred on success, or a negative error code on failure.
519 static int drm_dp_i2c_do_msg(struct drm_dp_aux
*aux
, struct drm_dp_aux_msg
*msg
)
521 unsigned int retry
, defer_i2c
;
524 * DP1.2 sections 2.7.7.1.5.6.1 and 2.7.7.1.6.6.1: A DP Source device
525 * is required to retry at least seven times upon receiving AUX_DEFER
526 * before giving up the AUX transaction.
528 * We also try to account for the i2c bus speed.
530 int max_retries
= max(7, drm_dp_i2c_retry_count(msg
, dp_aux_i2c_speed_khz
));
532 for (retry
= 0, defer_i2c
= 0; retry
< (max_retries
+ defer_i2c
); retry
++) {
533 mutex_lock(&aux
->hw_mutex
);
534 ret
= aux
->transfer(aux
, msg
);
535 mutex_unlock(&aux
->hw_mutex
);
540 DRM_DEBUG_KMS("transaction failed: %d\n", ret
);
545 switch (msg
->reply
& DP_AUX_NATIVE_REPLY_MASK
) {
546 case DP_AUX_NATIVE_REPLY_ACK
:
548 * For I2C-over-AUX transactions this isn't enough, we
549 * need to check for the I2C ACK reply.
553 case DP_AUX_NATIVE_REPLY_NACK
:
554 DRM_DEBUG_KMS("native nack (result=%d, size=%zu)\n", ret
, msg
->size
);
557 case DP_AUX_NATIVE_REPLY_DEFER
:
558 DRM_DEBUG_KMS("native defer\n");
560 * We could check for I2C bit rate capabilities and if
561 * available adjust this interval. We could also be
562 * more careful with DP-to-legacy adapters where a
563 * long legacy cable may force very low I2C bit rates.
565 * For now just defer for long enough to hopefully be
566 * safe for all use-cases.
568 usleep_range(AUX_RETRY_INTERVAL
, AUX_RETRY_INTERVAL
+ 100);
572 DRM_ERROR("invalid native reply %#04x\n", msg
->reply
);
576 switch (msg
->reply
& DP_AUX_I2C_REPLY_MASK
) {
577 case DP_AUX_I2C_REPLY_ACK
:
579 * Both native ACK and I2C ACK replies received. We
580 * can assume the transfer was successful.
584 case DP_AUX_I2C_REPLY_NACK
:
585 DRM_DEBUG_KMS("I2C nack (result=%d, size=%zu\n", ret
, msg
->size
);
586 aux
->i2c_nack_count
++;
589 case DP_AUX_I2C_REPLY_DEFER
:
590 DRM_DEBUG_KMS("I2C defer\n");
591 /* DP Compliance Test 4.2.2.5 Requirement:
592 * Must have at least 7 retries for I2C defers on the
593 * transaction to pass this test
595 aux
->i2c_defer_count
++;
598 usleep_range(AUX_RETRY_INTERVAL
, AUX_RETRY_INTERVAL
+ 100);
602 DRM_ERROR("invalid I2C reply %#04x\n", msg
->reply
);
607 DRM_DEBUG_KMS("too many retries, giving up\n");
612 * Keep retrying drm_dp_i2c_do_msg until all data has been transferred.
614 * Returns an error code on failure, or a recommended transfer size on success.
616 static int drm_dp_i2c_drain_msg(struct drm_dp_aux
*aux
, struct drm_dp_aux_msg
*orig_msg
)
618 int err
, ret
= orig_msg
->size
;
619 struct drm_dp_aux_msg msg
= *orig_msg
;
621 while (msg
.size
> 0) {
622 err
= drm_dp_i2c_do_msg(aux
, &msg
);
624 return err
== 0 ? -EPROTO
: err
;
626 if (err
< msg
.size
&& err
< ret
) {
627 DRM_DEBUG_KMS("Partial I2C reply: requested %zu bytes got %d bytes\n",
640 * Bizlink designed DP->DVI-D Dual Link adapters require the I2C over AUX
641 * packets to be as large as possible. If not, the I2C transactions never
642 * succeed. Hence the default is maximum.
644 static int dp_aux_i2c_transfer_size __read_mostly
= DP_AUX_MAX_PAYLOAD_BYTES
;
645 module_param_unsafe(dp_aux_i2c_transfer_size
, int, 0644);
646 MODULE_PARM_DESC(dp_aux_i2c_transfer_size
,
647 "Number of bytes to transfer in a single I2C over DP AUX CH message, (1-16, default 16)");
649 static int drm_dp_i2c_xfer(struct i2c_adapter
*adapter
, struct i2c_msg
*msgs
,
652 struct drm_dp_aux
*aux
= adapter
->algo_data
;
654 unsigned transfer_size
;
655 struct drm_dp_aux_msg msg
;
658 dp_aux_i2c_transfer_size
= clamp(dp_aux_i2c_transfer_size
, 1, DP_AUX_MAX_PAYLOAD_BYTES
);
660 memset(&msg
, 0, sizeof(msg
));
662 for (i
= 0; i
< num
; i
++) {
663 msg
.address
= msgs
[i
].addr
;
664 msg
.request
= (msgs
[i
].flags
& I2C_M_RD
) ?
667 msg
.request
|= DP_AUX_I2C_MOT
;
668 /* Send a bare address packet to start the transaction.
669 * Zero sized messages specify an address only (bare
670 * address) transaction.
674 err
= drm_dp_i2c_do_msg(aux
, &msg
);
677 /* We want each transaction to be as large as possible, but
678 * we'll go to smaller sizes if the hardware gives us a
681 transfer_size
= dp_aux_i2c_transfer_size
;
682 for (j
= 0; j
< msgs
[i
].len
; j
+= msg
.size
) {
683 msg
.buffer
= msgs
[i
].buf
+ j
;
684 msg
.size
= min(transfer_size
, msgs
[i
].len
- j
);
686 err
= drm_dp_i2c_drain_msg(aux
, &msg
);
696 /* Send a bare address packet to close out the transaction.
697 * Zero sized messages specify an address only (bare
698 * address) transaction.
700 msg
.request
&= ~DP_AUX_I2C_MOT
;
703 (void)drm_dp_i2c_do_msg(aux
, &msg
);
708 static const struct i2c_algorithm drm_dp_i2c_algo
= {
709 .functionality
= drm_dp_i2c_functionality
,
710 .master_xfer
= drm_dp_i2c_xfer
,
714 * drm_dp_aux_register() - initialise and register aux channel
715 * @aux: DisplayPort AUX channel
717 * Returns 0 on success or a negative error code on failure.
719 int drm_dp_aux_register(struct drm_dp_aux
*aux
)
721 mutex_init(&aux
->hw_mutex
);
723 aux
->ddc
.algo
= &drm_dp_i2c_algo
;
724 aux
->ddc
.algo_data
= aux
;
725 aux
->ddc
.retries
= 3;
727 aux
->ddc
.class = I2C_CLASS_DDC
;
728 aux
->ddc
.owner
= THIS_MODULE
;
729 aux
->ddc
.dev
.parent
= aux
->dev
;
730 aux
->ddc
.dev
.of_node
= aux
->dev
->of_node
;
732 strlcpy(aux
->ddc
.name
, aux
->name
? aux
->name
: dev_name(aux
->dev
),
733 sizeof(aux
->ddc
.name
));
735 return i2c_add_adapter(&aux
->ddc
);
737 EXPORT_SYMBOL(drm_dp_aux_register
);
740 * drm_dp_aux_unregister() - unregister an AUX adapter
741 * @aux: DisplayPort AUX channel
743 void drm_dp_aux_unregister(struct drm_dp_aux
*aux
)
745 i2c_del_adapter(&aux
->ddc
);
747 EXPORT_SYMBOL(drm_dp_aux_unregister
);