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>
33 #include "drm_crtc_helper_internal.h"
38 * These functions contain some common logic and helpers at various abstraction
39 * levels to deal with Display Port sink devices and related things like DP aux
40 * channel transfers, EDID reading over DP aux channels, decoding certain DPCD
44 /* Helpers for DP link training */
45 static u8
dp_link_status(const u8 link_status
[DP_LINK_STATUS_SIZE
], int r
)
47 return link_status
[r
- DP_LANE0_1_STATUS
];
50 static u8
dp_get_lane_status(const u8 link_status
[DP_LINK_STATUS_SIZE
],
53 int i
= DP_LANE0_1_STATUS
+ (lane
>> 1);
54 int s
= (lane
& 1) * 4;
55 u8 l
= dp_link_status(link_status
, i
);
56 return (l
>> s
) & 0xf;
59 bool drm_dp_channel_eq_ok(const u8 link_status
[DP_LINK_STATUS_SIZE
],
66 lane_align
= dp_link_status(link_status
,
67 DP_LANE_ALIGN_STATUS_UPDATED
);
68 if ((lane_align
& DP_INTERLANE_ALIGN_DONE
) == 0)
70 for (lane
= 0; lane
< lane_count
; lane
++) {
71 lane_status
= dp_get_lane_status(link_status
, lane
);
72 if ((lane_status
& DP_CHANNEL_EQ_BITS
) != DP_CHANNEL_EQ_BITS
)
77 EXPORT_SYMBOL(drm_dp_channel_eq_ok
);
79 bool drm_dp_clock_recovery_ok(const u8 link_status
[DP_LINK_STATUS_SIZE
],
85 for (lane
= 0; lane
< lane_count
; lane
++) {
86 lane_status
= dp_get_lane_status(link_status
, lane
);
87 if ((lane_status
& DP_LANE_CR_DONE
) == 0)
92 EXPORT_SYMBOL(drm_dp_clock_recovery_ok
);
94 u8
drm_dp_get_adjust_request_voltage(const u8 link_status
[DP_LINK_STATUS_SIZE
],
97 int i
= DP_ADJUST_REQUEST_LANE0_1
+ (lane
>> 1);
99 DP_ADJUST_VOLTAGE_SWING_LANE1_SHIFT
:
100 DP_ADJUST_VOLTAGE_SWING_LANE0_SHIFT
);
101 u8 l
= dp_link_status(link_status
, i
);
103 return ((l
>> s
) & 0x3) << DP_TRAIN_VOLTAGE_SWING_SHIFT
;
105 EXPORT_SYMBOL(drm_dp_get_adjust_request_voltage
);
107 u8
drm_dp_get_adjust_request_pre_emphasis(const u8 link_status
[DP_LINK_STATUS_SIZE
],
110 int i
= DP_ADJUST_REQUEST_LANE0_1
+ (lane
>> 1);
111 int s
= ((lane
& 1) ?
112 DP_ADJUST_PRE_EMPHASIS_LANE1_SHIFT
:
113 DP_ADJUST_PRE_EMPHASIS_LANE0_SHIFT
);
114 u8 l
= dp_link_status(link_status
, i
);
116 return ((l
>> s
) & 0x3) << DP_TRAIN_PRE_EMPHASIS_SHIFT
;
118 EXPORT_SYMBOL(drm_dp_get_adjust_request_pre_emphasis
);
120 void drm_dp_link_train_clock_recovery_delay(const u8 dpcd
[DP_RECEIVER_CAP_SIZE
]) {
121 if (dpcd
[DP_TRAINING_AUX_RD_INTERVAL
] == 0)
124 mdelay(dpcd
[DP_TRAINING_AUX_RD_INTERVAL
] * 4);
126 EXPORT_SYMBOL(drm_dp_link_train_clock_recovery_delay
);
128 void drm_dp_link_train_channel_eq_delay(const u8 dpcd
[DP_RECEIVER_CAP_SIZE
]) {
129 if (dpcd
[DP_TRAINING_AUX_RD_INTERVAL
] == 0)
132 mdelay(dpcd
[DP_TRAINING_AUX_RD_INTERVAL
] * 4);
134 EXPORT_SYMBOL(drm_dp_link_train_channel_eq_delay
);
136 u8
drm_dp_link_rate_to_bw_code(int link_rate
)
141 return DP_LINK_BW_1_62
;
143 return DP_LINK_BW_2_7
;
145 return DP_LINK_BW_5_4
;
148 EXPORT_SYMBOL(drm_dp_link_rate_to_bw_code
);
150 int drm_dp_bw_code_to_link_rate(u8 link_bw
)
153 case DP_LINK_BW_1_62
:
162 EXPORT_SYMBOL(drm_dp_bw_code_to_link_rate
);
164 #define AUX_RETRY_INTERVAL 500 /* us */
169 * The DisplayPort AUX channel is an abstraction to allow generic, driver-
170 * independent access to AUX functionality. Drivers can take advantage of
171 * this by filling in the fields of the drm_dp_aux structure.
173 * Transactions are described using a hardware-independent drm_dp_aux_msg
174 * structure, which is passed into a driver's .transfer() implementation.
175 * Both native and I2C-over-AUX transactions are supported.
178 static int drm_dp_dpcd_access(struct drm_dp_aux
*aux
, u8 request
,
179 unsigned int offset
, void *buffer
, size_t size
)
181 struct drm_dp_aux_msg msg
;
182 unsigned int retry
, native_reply
;
183 int err
= 0, ret
= 0;
185 memset(&msg
, 0, sizeof(msg
));
186 msg
.address
= offset
;
187 msg
.request
= request
;
191 mutex_lock(&aux
->hw_mutex
);
194 * The specification doesn't give any recommendation on how often to
195 * retry native transactions. We used to retry 7 times like for
196 * aux i2c transactions but real world devices this wasn't
197 * sufficient, bump to 32 which makes Dell 4k monitors happier.
199 for (retry
= 0; retry
< 32; retry
++) {
200 if (ret
!= 0 && ret
!= -ETIMEDOUT
) {
201 usleep_range(AUX_RETRY_INTERVAL
,
202 AUX_RETRY_INTERVAL
+ 100);
205 ret
= aux
->transfer(aux
, &msg
);
208 native_reply
= msg
.reply
& DP_AUX_NATIVE_REPLY_MASK
;
209 if (native_reply
== DP_AUX_NATIVE_REPLY_ACK
) {
219 * We want the error we return to be the error we received on
220 * the first transaction, since we may get a different error the
227 DRM_DEBUG_KMS("Too many retries, giving up. First error: %d\n", err
);
231 mutex_unlock(&aux
->hw_mutex
);
236 * drm_dp_dpcd_read() - read a series of bytes from the DPCD
237 * @aux: DisplayPort AUX channel
238 * @offset: address of the (first) register to read
239 * @buffer: buffer to store the register values
240 * @size: number of bytes in @buffer
242 * Returns the number of bytes transferred on success, or a negative error
243 * code on failure. -EIO is returned if the request was NAKed by the sink or
244 * if the retry count was exceeded. If not all bytes were transferred, this
245 * function returns -EPROTO. Errors from the underlying AUX channel transfer
246 * function, with the exception of -EBUSY (which causes the transaction to
247 * be retried), are propagated to the caller.
249 ssize_t
drm_dp_dpcd_read(struct drm_dp_aux
*aux
, unsigned int offset
,
250 void *buffer
, size_t size
)
255 * HP ZR24w corrupts the first DPCD access after entering power save
256 * mode. Eg. on a read, the entire buffer will be filled with the same
257 * byte. Do a throw away read to avoid corrupting anything we care
258 * about. Afterwards things will work correctly until the monitor
259 * gets woken up and subsequently re-enters power save mode.
261 * The user pressing any button on the monitor is enough to wake it
262 * up, so there is no particularly good place to do the workaround.
263 * We just have to do it before any DPCD access and hope that the
264 * monitor doesn't power down exactly after the throw away read.
266 ret
= drm_dp_dpcd_access(aux
, DP_AUX_NATIVE_READ
, DP_DPCD_REV
, buffer
,
271 return drm_dp_dpcd_access(aux
, DP_AUX_NATIVE_READ
, offset
, buffer
,
274 EXPORT_SYMBOL(drm_dp_dpcd_read
);
277 * drm_dp_dpcd_write() - write a series of bytes to the DPCD
278 * @aux: DisplayPort AUX channel
279 * @offset: address of the (first) register to write
280 * @buffer: buffer containing the values to write
281 * @size: number of bytes in @buffer
283 * Returns the number of bytes transferred on success, or a negative error
284 * code on failure. -EIO is returned if the request was NAKed by the sink or
285 * if the retry count was exceeded. If not all bytes were transferred, this
286 * function returns -EPROTO. Errors from the underlying AUX channel transfer
287 * function, with the exception of -EBUSY (which causes the transaction to
288 * be retried), are propagated to the caller.
290 ssize_t
drm_dp_dpcd_write(struct drm_dp_aux
*aux
, unsigned int offset
,
291 void *buffer
, size_t size
)
293 return drm_dp_dpcd_access(aux
, DP_AUX_NATIVE_WRITE
, offset
, buffer
,
296 EXPORT_SYMBOL(drm_dp_dpcd_write
);
299 * drm_dp_dpcd_read_link_status() - read DPCD link status (bytes 0x202-0x207)
300 * @aux: DisplayPort AUX channel
301 * @status: buffer to store the link status in (must be at least 6 bytes)
303 * Returns the number of bytes transferred on success or a negative error
306 int drm_dp_dpcd_read_link_status(struct drm_dp_aux
*aux
,
307 u8 status
[DP_LINK_STATUS_SIZE
])
309 return drm_dp_dpcd_read(aux
, DP_LANE0_1_STATUS
, status
,
310 DP_LINK_STATUS_SIZE
);
312 EXPORT_SYMBOL(drm_dp_dpcd_read_link_status
);
315 * drm_dp_link_probe() - probe a DisplayPort link for capabilities
316 * @aux: DisplayPort AUX channel
317 * @link: pointer to structure in which to return link capabilities
319 * The structure filled in by this function can usually be passed directly
320 * into drm_dp_link_power_up() and drm_dp_link_configure() to power up and
321 * configure the link based on the link's capabilities.
323 * Returns 0 on success or a negative error code on failure.
325 int drm_dp_link_probe(struct drm_dp_aux
*aux
, struct drm_dp_link
*link
)
330 memset(link
, 0, sizeof(*link
));
332 err
= drm_dp_dpcd_read(aux
, DP_DPCD_REV
, values
, sizeof(values
));
336 link
->revision
= values
[0];
337 link
->rate
= drm_dp_bw_code_to_link_rate(values
[1]);
338 link
->num_lanes
= values
[2] & DP_MAX_LANE_COUNT_MASK
;
340 if (values
[2] & DP_ENHANCED_FRAME_CAP
)
341 link
->capabilities
|= DP_LINK_CAP_ENHANCED_FRAMING
;
345 EXPORT_SYMBOL(drm_dp_link_probe
);
348 * drm_dp_link_power_up() - power up a DisplayPort link
349 * @aux: DisplayPort AUX channel
350 * @link: pointer to a structure containing the link configuration
352 * Returns 0 on success or a negative error code on failure.
354 int drm_dp_link_power_up(struct drm_dp_aux
*aux
, struct drm_dp_link
*link
)
359 /* DP_SET_POWER register is only available on DPCD v1.1 and later */
360 if (link
->revision
< 0x11)
363 err
= drm_dp_dpcd_readb(aux
, DP_SET_POWER
, &value
);
367 value
&= ~DP_SET_POWER_MASK
;
368 value
|= DP_SET_POWER_D0
;
370 err
= drm_dp_dpcd_writeb(aux
, DP_SET_POWER
, value
);
375 * According to the DP 1.1 specification, a "Sink Device must exit the
376 * power saving state within 1 ms" (Section 2.5.3.1, Table 5-52, "Sink
377 * Control Field" (register 0x600).
379 usleep_range(1000, 2000);
383 EXPORT_SYMBOL(drm_dp_link_power_up
);
386 * drm_dp_link_power_down() - power down a DisplayPort link
387 * @aux: DisplayPort AUX channel
388 * @link: pointer to a structure containing the link configuration
390 * Returns 0 on success or a negative error code on failure.
392 int drm_dp_link_power_down(struct drm_dp_aux
*aux
, struct drm_dp_link
*link
)
397 /* DP_SET_POWER register is only available on DPCD v1.1 and later */
398 if (link
->revision
< 0x11)
401 err
= drm_dp_dpcd_readb(aux
, DP_SET_POWER
, &value
);
405 value
&= ~DP_SET_POWER_MASK
;
406 value
|= DP_SET_POWER_D3
;
408 err
= drm_dp_dpcd_writeb(aux
, DP_SET_POWER
, value
);
414 EXPORT_SYMBOL(drm_dp_link_power_down
);
417 * drm_dp_link_configure() - configure a DisplayPort link
418 * @aux: DisplayPort AUX channel
419 * @link: pointer to a structure containing the link configuration
421 * Returns 0 on success or a negative error code on failure.
423 int drm_dp_link_configure(struct drm_dp_aux
*aux
, struct drm_dp_link
*link
)
428 values
[0] = drm_dp_link_rate_to_bw_code(link
->rate
);
429 values
[1] = link
->num_lanes
;
431 if (link
->capabilities
& DP_LINK_CAP_ENHANCED_FRAMING
)
432 values
[1] |= DP_LANE_COUNT_ENHANCED_FRAME_EN
;
434 err
= drm_dp_dpcd_write(aux
, DP_LINK_BW_SET
, values
, sizeof(values
));
440 EXPORT_SYMBOL(drm_dp_link_configure
);
443 * I2C-over-AUX implementation
446 static u32
drm_dp_i2c_functionality(struct i2c_adapter
*adapter
)
448 return I2C_FUNC_I2C
| I2C_FUNC_SMBUS_EMUL
|
449 I2C_FUNC_SMBUS_READ_BLOCK_DATA
|
450 I2C_FUNC_SMBUS_BLOCK_PROC_CALL
|
454 static void drm_dp_i2c_msg_write_status_update(struct drm_dp_aux_msg
*msg
)
457 * In case of i2c defer or short i2c ack reply to a write,
458 * we need to switch to WRITE_STATUS_UPDATE to drain the
459 * rest of the message
461 if ((msg
->request
& ~DP_AUX_I2C_MOT
) == DP_AUX_I2C_WRITE
) {
462 msg
->request
&= DP_AUX_I2C_MOT
;
463 msg
->request
|= DP_AUX_I2C_WRITE_STATUS_UPDATE
;
467 #define AUX_PRECHARGE_LEN 10 /* 10 to 16 */
468 #define AUX_SYNC_LEN (16 + 4) /* preamble + AUX_SYNC_END */
469 #define AUX_STOP_LEN 4
470 #define AUX_CMD_LEN 4
471 #define AUX_ADDRESS_LEN 20
472 #define AUX_REPLY_PAD_LEN 4
473 #define AUX_LENGTH_LEN 8
476 * Calculate the duration of the AUX request/reply in usec. Gives the
477 * "best" case estimate, ie. successful while as short as possible.
479 static int drm_dp_aux_req_duration(const struct drm_dp_aux_msg
*msg
)
481 int len
= AUX_PRECHARGE_LEN
+ AUX_SYNC_LEN
+ AUX_STOP_LEN
+
482 AUX_CMD_LEN
+ AUX_ADDRESS_LEN
+ AUX_LENGTH_LEN
;
484 if ((msg
->request
& DP_AUX_I2C_READ
) == 0)
485 len
+= msg
->size
* 8;
490 static int drm_dp_aux_reply_duration(const struct drm_dp_aux_msg
*msg
)
492 int len
= AUX_PRECHARGE_LEN
+ AUX_SYNC_LEN
+ AUX_STOP_LEN
+
493 AUX_CMD_LEN
+ AUX_REPLY_PAD_LEN
;
496 * For read we expect what was asked. For writes there will
497 * be 0 or 1 data bytes. Assume 0 for the "best" case.
499 if (msg
->request
& DP_AUX_I2C_READ
)
500 len
+= msg
->size
* 8;
505 #define I2C_START_LEN 1
506 #define I2C_STOP_LEN 1
507 #define I2C_ADDR_LEN 9 /* ADDRESS + R/W + ACK/NACK */
508 #define I2C_DATA_LEN 9 /* DATA + ACK/NACK */
511 * Calculate the length of the i2c transfer in usec, assuming
512 * the i2c bus speed is as specified. Gives the the "worst"
513 * case estimate, ie. successful while as long as possible.
514 * Doesn't account the the "MOT" bit, and instead assumes each
515 * message includes a START, ADDRESS and STOP. Neither does it
516 * account for additional random variables such as clock stretching.
518 static int drm_dp_i2c_msg_duration(const struct drm_dp_aux_msg
*msg
,
521 /* AUX bitrate is 1MHz, i2c bitrate as specified */
522 return DIV_ROUND_UP((I2C_START_LEN
+ I2C_ADDR_LEN
+
523 msg
->size
* I2C_DATA_LEN
+
524 I2C_STOP_LEN
) * 1000, i2c_speed_khz
);
528 * Deterine how many retries should be attempted to successfully transfer
529 * the specified message, based on the estimated durations of the
530 * i2c and AUX transfers.
532 static int drm_dp_i2c_retry_count(const struct drm_dp_aux_msg
*msg
,
535 int aux_time_us
= drm_dp_aux_req_duration(msg
) +
536 drm_dp_aux_reply_duration(msg
);
537 int i2c_time_us
= drm_dp_i2c_msg_duration(msg
, i2c_speed_khz
);
539 return DIV_ROUND_UP(i2c_time_us
, aux_time_us
+ AUX_RETRY_INTERVAL
);
543 * FIXME currently assumes 10 kHz as some real world devices seem
544 * to require it. We should query/set the speed via DPCD if supported.
546 static int dp_aux_i2c_speed_khz __read_mostly
= 10;
547 module_param_unsafe(dp_aux_i2c_speed_khz
, int, 0644);
548 MODULE_PARM_DESC(dp_aux_i2c_speed_khz
,
549 "Assumed speed of the i2c bus in kHz, (1-400, default 10)");
552 * Transfer a single I2C-over-AUX message and handle various error conditions,
553 * retrying the transaction as appropriate. It is assumed that the
554 * aux->transfer function does not modify anything in the msg other than the
557 * Returns bytes transferred on success, or a negative error code on failure.
559 static int drm_dp_i2c_do_msg(struct drm_dp_aux
*aux
, struct drm_dp_aux_msg
*msg
)
561 unsigned int retry
, defer_i2c
;
564 * DP1.2 sections 2.7.7.1.5.6.1 and 2.7.7.1.6.6.1: A DP Source device
565 * is required to retry at least seven times upon receiving AUX_DEFER
566 * before giving up the AUX transaction.
568 * We also try to account for the i2c bus speed.
570 int max_retries
= max(7, drm_dp_i2c_retry_count(msg
, dp_aux_i2c_speed_khz
));
572 for (retry
= 0, defer_i2c
= 0; retry
< (max_retries
+ defer_i2c
); retry
++) {
573 ret
= aux
->transfer(aux
, msg
);
579 * While timeouts can be errors, they're usually normal
580 * behavior (for instance, when a driver tries to
581 * communicate with a non-existant DisplayPort device).
582 * Avoid spamming the kernel log with timeout errors.
584 if (ret
== -ETIMEDOUT
)
585 DRM_DEBUG_KMS_RATELIMITED("transaction timed out\n");
587 DRM_DEBUG_KMS("transaction failed: %d\n", ret
);
593 switch (msg
->reply
& DP_AUX_NATIVE_REPLY_MASK
) {
594 case DP_AUX_NATIVE_REPLY_ACK
:
596 * For I2C-over-AUX transactions this isn't enough, we
597 * need to check for the I2C ACK reply.
601 case DP_AUX_NATIVE_REPLY_NACK
:
602 DRM_DEBUG_KMS("native nack (result=%d, size=%zu)\n", ret
, msg
->size
);
605 case DP_AUX_NATIVE_REPLY_DEFER
:
606 DRM_DEBUG_KMS("native defer\n");
608 * We could check for I2C bit rate capabilities and if
609 * available adjust this interval. We could also be
610 * more careful with DP-to-legacy adapters where a
611 * long legacy cable may force very low I2C bit rates.
613 * For now just defer for long enough to hopefully be
614 * safe for all use-cases.
616 usleep_range(AUX_RETRY_INTERVAL
, AUX_RETRY_INTERVAL
+ 100);
620 DRM_ERROR("invalid native reply %#04x\n", msg
->reply
);
624 switch (msg
->reply
& DP_AUX_I2C_REPLY_MASK
) {
625 case DP_AUX_I2C_REPLY_ACK
:
627 * Both native ACK and I2C ACK replies received. We
628 * can assume the transfer was successful.
630 if (ret
!= msg
->size
)
631 drm_dp_i2c_msg_write_status_update(msg
);
634 case DP_AUX_I2C_REPLY_NACK
:
635 DRM_DEBUG_KMS("I2C nack (result=%d, size=%zu\n", ret
, msg
->size
);
636 aux
->i2c_nack_count
++;
639 case DP_AUX_I2C_REPLY_DEFER
:
640 DRM_DEBUG_KMS("I2C defer\n");
641 /* DP Compliance Test 4.2.2.5 Requirement:
642 * Must have at least 7 retries for I2C defers on the
643 * transaction to pass this test
645 aux
->i2c_defer_count
++;
648 usleep_range(AUX_RETRY_INTERVAL
, AUX_RETRY_INTERVAL
+ 100);
649 drm_dp_i2c_msg_write_status_update(msg
);
654 DRM_ERROR("invalid I2C reply %#04x\n", msg
->reply
);
659 DRM_DEBUG_KMS("too many retries, giving up\n");
663 static void drm_dp_i2c_msg_set_request(struct drm_dp_aux_msg
*msg
,
664 const struct i2c_msg
*i2c_msg
)
666 msg
->request
= (i2c_msg
->flags
& I2C_M_RD
) ?
667 DP_AUX_I2C_READ
: DP_AUX_I2C_WRITE
;
668 msg
->request
|= DP_AUX_I2C_MOT
;
672 * Keep retrying drm_dp_i2c_do_msg until all data has been transferred.
674 * Returns an error code on failure, or a recommended transfer size on success.
676 static int drm_dp_i2c_drain_msg(struct drm_dp_aux
*aux
, struct drm_dp_aux_msg
*orig_msg
)
678 int err
, ret
= orig_msg
->size
;
679 struct drm_dp_aux_msg msg
= *orig_msg
;
681 while (msg
.size
> 0) {
682 err
= drm_dp_i2c_do_msg(aux
, &msg
);
684 return err
== 0 ? -EPROTO
: err
;
686 if (err
< msg
.size
&& err
< ret
) {
687 DRM_DEBUG_KMS("Partial I2C reply: requested %zu bytes got %d bytes\n",
700 * Bizlink designed DP->DVI-D Dual Link adapters require the I2C over AUX
701 * packets to be as large as possible. If not, the I2C transactions never
702 * succeed. Hence the default is maximum.
704 static int dp_aux_i2c_transfer_size __read_mostly
= DP_AUX_MAX_PAYLOAD_BYTES
;
705 module_param_unsafe(dp_aux_i2c_transfer_size
, int, 0644);
706 MODULE_PARM_DESC(dp_aux_i2c_transfer_size
,
707 "Number of bytes to transfer in a single I2C over DP AUX CH message, (1-16, default 16)");
709 static int drm_dp_i2c_xfer(struct i2c_adapter
*adapter
, struct i2c_msg
*msgs
,
712 struct drm_dp_aux
*aux
= adapter
->algo_data
;
714 unsigned transfer_size
;
715 struct drm_dp_aux_msg msg
;
718 dp_aux_i2c_transfer_size
= clamp(dp_aux_i2c_transfer_size
, 1, DP_AUX_MAX_PAYLOAD_BYTES
);
720 memset(&msg
, 0, sizeof(msg
));
722 for (i
= 0; i
< num
; i
++) {
723 msg
.address
= msgs
[i
].addr
;
724 drm_dp_i2c_msg_set_request(&msg
, &msgs
[i
]);
725 /* Send a bare address packet to start the transaction.
726 * Zero sized messages specify an address only (bare
727 * address) transaction.
731 err
= drm_dp_i2c_do_msg(aux
, &msg
);
734 * Reset msg.request in case in case it got
735 * changed into a WRITE_STATUS_UPDATE.
737 drm_dp_i2c_msg_set_request(&msg
, &msgs
[i
]);
741 /* We want each transaction to be as large as possible, but
742 * we'll go to smaller sizes if the hardware gives us a
745 transfer_size
= dp_aux_i2c_transfer_size
;
746 for (j
= 0; j
< msgs
[i
].len
; j
+= msg
.size
) {
747 msg
.buffer
= msgs
[i
].buf
+ j
;
748 msg
.size
= min(transfer_size
, msgs
[i
].len
- j
);
750 err
= drm_dp_i2c_drain_msg(aux
, &msg
);
753 * Reset msg.request in case in case it got
754 * changed into a WRITE_STATUS_UPDATE.
756 drm_dp_i2c_msg_set_request(&msg
, &msgs
[i
]);
767 /* Send a bare address packet to close out the transaction.
768 * Zero sized messages specify an address only (bare
769 * address) transaction.
771 msg
.request
&= ~DP_AUX_I2C_MOT
;
774 (void)drm_dp_i2c_do_msg(aux
, &msg
);
779 static const struct i2c_algorithm drm_dp_i2c_algo
= {
780 .functionality
= drm_dp_i2c_functionality
,
781 .master_xfer
= drm_dp_i2c_xfer
,
784 static struct drm_dp_aux
*i2c_to_aux(struct i2c_adapter
*i2c
)
786 return container_of(i2c
, struct drm_dp_aux
, ddc
);
789 static void lock_bus(struct i2c_adapter
*i2c
, unsigned int flags
)
791 mutex_lock(&i2c_to_aux(i2c
)->hw_mutex
);
794 static int trylock_bus(struct i2c_adapter
*i2c
, unsigned int flags
)
796 return mutex_trylock(&i2c_to_aux(i2c
)->hw_mutex
);
799 static void unlock_bus(struct i2c_adapter
*i2c
, unsigned int flags
)
801 mutex_unlock(&i2c_to_aux(i2c
)->hw_mutex
);
805 * drm_dp_aux_init() - minimally initialise an aux channel
806 * @aux: DisplayPort AUX channel
808 * If you need to use the drm_dp_aux's i2c adapter prior to registering it
809 * with the outside world, call drm_dp_aux_init() first. You must still
810 * call drm_dp_aux_register() once the connector has been registered to
811 * allow userspace access to the auxiliary DP channel.
813 void drm_dp_aux_init(struct drm_dp_aux
*aux
)
815 mutex_init(&aux
->hw_mutex
);
817 aux
->ddc
.algo
= &drm_dp_i2c_algo
;
818 aux
->ddc
.algo_data
= aux
;
819 aux
->ddc
.retries
= 3;
821 aux
->ddc
.lock_bus
= lock_bus
;
822 aux
->ddc
.trylock_bus
= trylock_bus
;
823 aux
->ddc
.unlock_bus
= unlock_bus
;
825 EXPORT_SYMBOL(drm_dp_aux_init
);
828 * drm_dp_aux_register() - initialise and register aux channel
829 * @aux: DisplayPort AUX channel
831 * Automatically calls drm_dp_aux_init() if this hasn't been done yet.
833 * Returns 0 on success or a negative error code on failure.
835 int drm_dp_aux_register(struct drm_dp_aux
*aux
)
840 drm_dp_aux_init(aux
);
842 aux
->ddc
.class = I2C_CLASS_DDC
;
843 aux
->ddc
.owner
= THIS_MODULE
;
844 aux
->ddc
.dev
.parent
= aux
->dev
;
845 aux
->ddc
.dev
.of_node
= aux
->dev
->of_node
;
847 strlcpy(aux
->ddc
.name
, aux
->name
? aux
->name
: dev_name(aux
->dev
),
848 sizeof(aux
->ddc
.name
));
850 ret
= drm_dp_aux_register_devnode(aux
);
854 ret
= i2c_add_adapter(&aux
->ddc
);
856 drm_dp_aux_unregister_devnode(aux
);
862 EXPORT_SYMBOL(drm_dp_aux_register
);
865 * drm_dp_aux_unregister() - unregister an AUX adapter
866 * @aux: DisplayPort AUX channel
868 void drm_dp_aux_unregister(struct drm_dp_aux
*aux
)
870 drm_dp_aux_unregister_devnode(aux
);
871 i2c_del_adapter(&aux
->ddc
);
873 EXPORT_SYMBOL(drm_dp_aux_unregister
);
875 #define PSR_SETUP_TIME(x) [DP_PSR_SETUP_TIME_ ## x >> DP_PSR_SETUP_TIME_SHIFT] = (x)
878 * drm_dp_psr_setup_time() - PSR setup in time usec
879 * @psr_cap: PSR capabilities from DPCD
882 * PSR setup time for the panel in microseconds, negative
883 * error code on failure.
885 int drm_dp_psr_setup_time(const u8 psr_cap
[EDP_PSR_RECEIVER_CAP_SIZE
])
887 static const u16 psr_setup_time_us
[] = {
897 i
= (psr_cap
[1] & DP_PSR_SETUP_TIME_MASK
) >> DP_PSR_SETUP_TIME_SHIFT
;
898 if (i
>= ARRAY_SIZE(psr_setup_time_us
))
901 return psr_setup_time_us
[i
];
903 EXPORT_SYMBOL(drm_dp_psr_setup_time
);
905 #undef PSR_SETUP_TIME