xref: /linux/include/drm/display/drm_dp_helper.h (revision 3027ce13e04eee76539ca65c2cb1028a01c8c508)
1 /*
2  * Copyright © 2008 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 #ifndef _DRM_DP_HELPER_H_
24 #define _DRM_DP_HELPER_H_
25 
26 #include <linux/delay.h>
27 #include <linux/i2c.h>
28 
29 #include <drm/display/drm_dp.h>
30 #include <drm/drm_connector.h>
31 
32 struct drm_device;
33 struct drm_dp_aux;
34 struct drm_panel;
35 
36 bool drm_dp_channel_eq_ok(const u8 link_status[DP_LINK_STATUS_SIZE],
37 			  int lane_count);
38 bool drm_dp_clock_recovery_ok(const u8 link_status[DP_LINK_STATUS_SIZE],
39 			      int lane_count);
40 u8 drm_dp_get_adjust_request_voltage(const u8 link_status[DP_LINK_STATUS_SIZE],
41 				     int lane);
42 u8 drm_dp_get_adjust_request_pre_emphasis(const u8 link_status[DP_LINK_STATUS_SIZE],
43 					  int lane);
44 u8 drm_dp_get_adjust_tx_ffe_preset(const u8 link_status[DP_LINK_STATUS_SIZE],
45 				   int lane);
46 
47 int drm_dp_read_clock_recovery_delay(struct drm_dp_aux *aux, const u8 dpcd[DP_RECEIVER_CAP_SIZE],
48 				     enum drm_dp_phy dp_phy, bool uhbr);
49 int drm_dp_read_channel_eq_delay(struct drm_dp_aux *aux, const u8 dpcd[DP_RECEIVER_CAP_SIZE],
50 				 enum drm_dp_phy dp_phy, bool uhbr);
51 
52 void drm_dp_link_train_clock_recovery_delay(const struct drm_dp_aux *aux,
53 					    const u8 dpcd[DP_RECEIVER_CAP_SIZE]);
54 void drm_dp_lttpr_link_train_clock_recovery_delay(void);
55 void drm_dp_link_train_channel_eq_delay(const struct drm_dp_aux *aux,
56 					const u8 dpcd[DP_RECEIVER_CAP_SIZE]);
57 void drm_dp_lttpr_link_train_channel_eq_delay(const struct drm_dp_aux *aux,
58 					      const u8 caps[DP_LTTPR_PHY_CAP_SIZE]);
59 
60 int drm_dp_128b132b_read_aux_rd_interval(struct drm_dp_aux *aux);
61 bool drm_dp_128b132b_lane_channel_eq_done(const u8 link_status[DP_LINK_STATUS_SIZE],
62 					  int lane_count);
63 bool drm_dp_128b132b_lane_symbol_locked(const u8 link_status[DP_LINK_STATUS_SIZE],
64 					int lane_count);
65 bool drm_dp_128b132b_eq_interlane_align_done(const u8 link_status[DP_LINK_STATUS_SIZE]);
66 bool drm_dp_128b132b_cds_interlane_align_done(const u8 link_status[DP_LINK_STATUS_SIZE]);
67 bool drm_dp_128b132b_link_training_failed(const u8 link_status[DP_LINK_STATUS_SIZE]);
68 
69 u8 drm_dp_link_rate_to_bw_code(int link_rate);
70 int drm_dp_bw_code_to_link_rate(u8 link_bw);
71 
72 const char *drm_dp_phy_name(enum drm_dp_phy dp_phy);
73 
74 /**
75  * struct drm_dp_vsc_sdp - drm DP VSC SDP
76  *
77  * This structure represents a DP VSC SDP of drm
78  * It is based on DP 1.4 spec [Table 2-116: VSC SDP Header Bytes] and
79  * [Table 2-117: VSC SDP Payload for DB16 through DB18]
80  *
81  * @sdp_type: secondary-data packet type
82  * @revision: revision number
83  * @length: number of valid data bytes
84  * @pixelformat: pixel encoding format
85  * @colorimetry: colorimetry format
86  * @bpc: bit per color
87  * @dynamic_range: dynamic range information
88  * @content_type: CTA-861-G defines content types and expected processing by a sink device
89  */
90 struct drm_dp_vsc_sdp {
91 	unsigned char sdp_type;
92 	unsigned char revision;
93 	unsigned char length;
94 	enum dp_pixelformat pixelformat;
95 	enum dp_colorimetry colorimetry;
96 	int bpc;
97 	enum dp_dynamic_range dynamic_range;
98 	enum dp_content_type content_type;
99 };
100 
101 /**
102  * struct drm_dp_as_sdp - drm DP Adaptive Sync SDP
103  *
104  * This structure represents a DP AS SDP of drm
105  * It is based on DP 2.1 spec [Table 2-126:  Adaptive-Sync SDP Header Bytes] and
106  * [Table 2-127: Adaptive-Sync SDP Payload for DB0 through DB8]
107  *
108  * @sdp_type: Secondary-data packet type
109  * @revision: Revision Number
110  * @length: Number of valid data bytes
111  * @vtotal: Minimum Vertical Vtotal
112  * @target_rr: Target Refresh
113  * @duration_incr_ms: Successive frame duration increase
114  * @duration_decr_ms: Successive frame duration decrease
115  * @operation_mode: Adaptive Sync Operation Mode
116  */
117 struct drm_dp_as_sdp {
118 	unsigned char sdp_type;
119 	unsigned char revision;
120 	unsigned char length;
121 	int vtotal;
122 	int target_rr;
123 	int duration_incr_ms;
124 	int duration_decr_ms;
125 	enum operation_mode mode;
126 };
127 
128 void drm_dp_as_sdp_log(struct drm_printer *p,
129 		       const struct drm_dp_as_sdp *as_sdp);
130 void drm_dp_vsc_sdp_log(struct drm_printer *p, const struct drm_dp_vsc_sdp *vsc);
131 
132 bool drm_dp_vsc_sdp_supported(struct drm_dp_aux *aux, const u8 dpcd[DP_RECEIVER_CAP_SIZE]);
133 bool drm_dp_as_sdp_supported(struct drm_dp_aux *aux, const u8 dpcd[DP_RECEIVER_CAP_SIZE]);
134 
135 int drm_dp_psr_setup_time(const u8 psr_cap[EDP_PSR_RECEIVER_CAP_SIZE]);
136 
137 static inline int
138 drm_dp_max_link_rate(const u8 dpcd[DP_RECEIVER_CAP_SIZE])
139 {
140 	return drm_dp_bw_code_to_link_rate(dpcd[DP_MAX_LINK_RATE]);
141 }
142 
143 static inline u8
144 drm_dp_max_lane_count(const u8 dpcd[DP_RECEIVER_CAP_SIZE])
145 {
146 	return dpcd[DP_MAX_LANE_COUNT] & DP_MAX_LANE_COUNT_MASK;
147 }
148 
149 static inline bool
150 drm_dp_enhanced_frame_cap(const u8 dpcd[DP_RECEIVER_CAP_SIZE])
151 {
152 	return dpcd[DP_DPCD_REV] >= 0x11 &&
153 		(dpcd[DP_MAX_LANE_COUNT] & DP_ENHANCED_FRAME_CAP);
154 }
155 
156 static inline bool
157 drm_dp_fast_training_cap(const u8 dpcd[DP_RECEIVER_CAP_SIZE])
158 {
159 	return dpcd[DP_DPCD_REV] >= 0x11 &&
160 		(dpcd[DP_MAX_DOWNSPREAD] & DP_NO_AUX_HANDSHAKE_LINK_TRAINING);
161 }
162 
163 static inline bool
164 drm_dp_tps3_supported(const u8 dpcd[DP_RECEIVER_CAP_SIZE])
165 {
166 	return dpcd[DP_DPCD_REV] >= 0x12 &&
167 		dpcd[DP_MAX_LANE_COUNT] & DP_TPS3_SUPPORTED;
168 }
169 
170 static inline bool
171 drm_dp_max_downspread(const u8 dpcd[DP_RECEIVER_CAP_SIZE])
172 {
173 	return dpcd[DP_DPCD_REV] >= 0x11 ||
174 		dpcd[DP_MAX_DOWNSPREAD] & DP_MAX_DOWNSPREAD_0_5;
175 }
176 
177 static inline bool
178 drm_dp_tps4_supported(const u8 dpcd[DP_RECEIVER_CAP_SIZE])
179 {
180 	return dpcd[DP_DPCD_REV] >= 0x14 &&
181 		dpcd[DP_MAX_DOWNSPREAD] & DP_TPS4_SUPPORTED;
182 }
183 
184 static inline u8
185 drm_dp_training_pattern_mask(const u8 dpcd[DP_RECEIVER_CAP_SIZE])
186 {
187 	return (dpcd[DP_DPCD_REV] >= 0x14) ? DP_TRAINING_PATTERN_MASK_1_4 :
188 		DP_TRAINING_PATTERN_MASK;
189 }
190 
191 static inline bool
192 drm_dp_is_branch(const u8 dpcd[DP_RECEIVER_CAP_SIZE])
193 {
194 	return dpcd[DP_DOWNSTREAMPORT_PRESENT] & DP_DWN_STRM_PORT_PRESENT;
195 }
196 
197 /* DP/eDP DSC support */
198 u8 drm_dp_dsc_sink_bpp_incr(const u8 dsc_dpcd[DP_DSC_RECEIVER_CAP_SIZE]);
199 u8 drm_dp_dsc_sink_max_slice_count(const u8 dsc_dpcd[DP_DSC_RECEIVER_CAP_SIZE],
200 				   bool is_edp);
201 u8 drm_dp_dsc_sink_line_buf_depth(const u8 dsc_dpcd[DP_DSC_RECEIVER_CAP_SIZE]);
202 int drm_dp_dsc_sink_supported_input_bpcs(const u8 dsc_dpc[DP_DSC_RECEIVER_CAP_SIZE],
203 					 u8 dsc_bpc[3]);
204 
205 static inline bool
206 drm_dp_sink_supports_dsc(const u8 dsc_dpcd[DP_DSC_RECEIVER_CAP_SIZE])
207 {
208 	return dsc_dpcd[DP_DSC_SUPPORT - DP_DSC_SUPPORT] &
209 		DP_DSC_DECOMPRESSION_IS_SUPPORTED;
210 }
211 
212 static inline u16
213 drm_edp_dsc_sink_output_bpp(const u8 dsc_dpcd[DP_DSC_RECEIVER_CAP_SIZE])
214 {
215 	return dsc_dpcd[DP_DSC_MAX_BITS_PER_PIXEL_LOW - DP_DSC_SUPPORT] |
216 		((dsc_dpcd[DP_DSC_MAX_BITS_PER_PIXEL_HI - DP_DSC_SUPPORT] &
217 		  DP_DSC_MAX_BITS_PER_PIXEL_HI_MASK) << 8);
218 }
219 
220 static inline u32
221 drm_dp_dsc_sink_max_slice_width(const u8 dsc_dpcd[DP_DSC_RECEIVER_CAP_SIZE])
222 {
223 	/* Max Slicewidth = Number of Pixels * 320 */
224 	return dsc_dpcd[DP_DSC_MAX_SLICE_WIDTH - DP_DSC_SUPPORT] *
225 		DP_DSC_SLICE_WIDTH_MULTIPLIER;
226 }
227 
228 /**
229  * drm_dp_dsc_sink_supports_format() - check if sink supports DSC with given output format
230  * @dsc_dpcd : DSC-capability DPCDs of the sink
231  * @output_format: output_format which is to be checked
232  *
233  * Returns true if the sink supports DSC with the given output_format, false otherwise.
234  */
235 static inline bool
236 drm_dp_dsc_sink_supports_format(const u8 dsc_dpcd[DP_DSC_RECEIVER_CAP_SIZE], u8 output_format)
237 {
238 	return dsc_dpcd[DP_DSC_DEC_COLOR_FORMAT_CAP - DP_DSC_SUPPORT] & output_format;
239 }
240 
241 /* Forward Error Correction Support on DP 1.4 */
242 static inline bool
243 drm_dp_sink_supports_fec(const u8 fec_capable)
244 {
245 	return fec_capable & DP_FEC_CAPABLE;
246 }
247 
248 static inline bool
249 drm_dp_channel_coding_supported(const u8 dpcd[DP_RECEIVER_CAP_SIZE])
250 {
251 	return dpcd[DP_MAIN_LINK_CHANNEL_CODING] & DP_CAP_ANSI_8B10B;
252 }
253 
254 static inline bool
255 drm_dp_alternate_scrambler_reset_cap(const u8 dpcd[DP_RECEIVER_CAP_SIZE])
256 {
257 	return dpcd[DP_EDP_CONFIGURATION_CAP] &
258 			DP_ALTERNATE_SCRAMBLER_RESET_CAP;
259 }
260 
261 /* Ignore MSA timing for Adaptive Sync support on DP 1.4 */
262 static inline bool
263 drm_dp_sink_can_do_video_without_timing_msa(const u8 dpcd[DP_RECEIVER_CAP_SIZE])
264 {
265 	return dpcd[DP_DOWN_STREAM_PORT_COUNT] &
266 		DP_MSA_TIMING_PAR_IGNORED;
267 }
268 
269 /**
270  * drm_edp_backlight_supported() - Check an eDP DPCD for VESA backlight support
271  * @edp_dpcd: The DPCD to check
272  *
273  * Note that currently this function will return %false for panels which support various DPCD
274  * backlight features but which require the brightness be set through PWM, and don't support setting
275  * the brightness level via the DPCD.
276  *
277  * Returns: %True if @edp_dpcd indicates that VESA backlight controls are supported, %false
278  * otherwise
279  */
280 static inline bool
281 drm_edp_backlight_supported(const u8 edp_dpcd[EDP_DISPLAY_CTL_CAP_SIZE])
282 {
283 	return !!(edp_dpcd[1] & DP_EDP_TCON_BACKLIGHT_ADJUSTMENT_CAP);
284 }
285 
286 /**
287  * drm_dp_is_uhbr_rate - Determine if a link rate is UHBR
288  * @link_rate: link rate in 10kbits/s units
289  *
290  * Determine if the provided link rate is an UHBR rate.
291  *
292  * Returns: %True if @link_rate is an UHBR rate.
293  */
294 static inline bool drm_dp_is_uhbr_rate(int link_rate)
295 {
296 	return link_rate >= 1000000;
297 }
298 
299 /*
300  * DisplayPort AUX channel
301  */
302 
303 /**
304  * struct drm_dp_aux_msg - DisplayPort AUX channel transaction
305  * @address: address of the (first) register to access
306  * @request: contains the type of transaction (see DP_AUX_* macros)
307  * @reply: upon completion, contains the reply type of the transaction
308  * @buffer: pointer to a transmission or reception buffer
309  * @size: size of @buffer
310  */
311 struct drm_dp_aux_msg {
312 	unsigned int address;
313 	u8 request;
314 	u8 reply;
315 	void *buffer;
316 	size_t size;
317 };
318 
319 struct cec_adapter;
320 struct drm_connector;
321 struct drm_edid;
322 
323 /**
324  * struct drm_dp_aux_cec - DisplayPort CEC-Tunneling-over-AUX
325  * @lock: mutex protecting this struct
326  * @adap: the CEC adapter for CEC-Tunneling-over-AUX support.
327  * @connector: the connector this CEC adapter is associated with
328  * @unregister_work: unregister the CEC adapter
329  */
330 struct drm_dp_aux_cec {
331 	struct mutex lock;
332 	struct cec_adapter *adap;
333 	struct drm_connector *connector;
334 	struct delayed_work unregister_work;
335 };
336 
337 /**
338  * struct drm_dp_aux - DisplayPort AUX channel
339  *
340  * An AUX channel can also be used to transport I2C messages to a sink. A
341  * typical application of that is to access an EDID that's present in the sink
342  * device. The @transfer() function can also be used to execute such
343  * transactions. The drm_dp_aux_register() function registers an I2C adapter
344  * that can be passed to drm_probe_ddc(). Upon removal, drivers should call
345  * drm_dp_aux_unregister() to remove the I2C adapter. The I2C adapter uses long
346  * transfers by default; if a partial response is received, the adapter will
347  * drop down to the size given by the partial response for this transaction
348  * only.
349  */
350 struct drm_dp_aux {
351 	/**
352 	 * @name: user-visible name of this AUX channel and the
353 	 * I2C-over-AUX adapter.
354 	 *
355 	 * It's also used to specify the name of the I2C adapter. If set
356 	 * to %NULL, dev_name() of @dev will be used.
357 	 */
358 	const char *name;
359 
360 	/**
361 	 * @ddc: I2C adapter that can be used for I2C-over-AUX
362 	 * communication
363 	 */
364 	struct i2c_adapter ddc;
365 
366 	/**
367 	 * @dev: pointer to struct device that is the parent for this
368 	 * AUX channel.
369 	 */
370 	struct device *dev;
371 
372 	/**
373 	 * @drm_dev: pointer to the &drm_device that owns this AUX channel.
374 	 * Beware, this may be %NULL before drm_dp_aux_register() has been
375 	 * called.
376 	 *
377 	 * It should be set to the &drm_device that will be using this AUX
378 	 * channel as early as possible. For many graphics drivers this should
379 	 * happen before drm_dp_aux_init(), however it's perfectly fine to set
380 	 * this field later so long as it's assigned before calling
381 	 * drm_dp_aux_register().
382 	 */
383 	struct drm_device *drm_dev;
384 
385 	/**
386 	 * @crtc: backpointer to the crtc that is currently using this
387 	 * AUX channel
388 	 */
389 	struct drm_crtc *crtc;
390 
391 	/**
392 	 * @hw_mutex: internal mutex used for locking transfers.
393 	 *
394 	 * Note that if the underlying hardware is shared among multiple
395 	 * channels, the driver needs to do additional locking to
396 	 * prevent concurrent access.
397 	 */
398 	struct mutex hw_mutex;
399 
400 	/**
401 	 * @crc_work: worker that captures CRCs for each frame
402 	 */
403 	struct work_struct crc_work;
404 
405 	/**
406 	 * @crc_count: counter of captured frame CRCs
407 	 */
408 	u8 crc_count;
409 
410 	/**
411 	 * @transfer: transfers a message representing a single AUX
412 	 * transaction.
413 	 *
414 	 * This is a hardware-specific implementation of how
415 	 * transactions are executed that the drivers must provide.
416 	 *
417 	 * A pointer to a &drm_dp_aux_msg structure describing the
418 	 * transaction is passed into this function. Upon success, the
419 	 * implementation should return the number of payload bytes that
420 	 * were transferred, or a negative error-code on failure.
421 	 *
422 	 * Helpers will propagate these errors, with the exception of
423 	 * the %-EBUSY error, which causes a transaction to be retried.
424 	 * On a short, helpers will return %-EPROTO to make it simpler
425 	 * to check for failure.
426 	 *
427 	 * The @transfer() function must only modify the reply field of
428 	 * the &drm_dp_aux_msg structure. The retry logic and i2c
429 	 * helpers assume this is the case.
430 	 *
431 	 * Also note that this callback can be called no matter the
432 	 * state @dev is in and also no matter what state the panel is
433 	 * in. It's expected:
434 	 *
435 	 * - If the @dev providing the AUX bus is currently unpowered then
436 	 *   it will power itself up for the transfer.
437 	 *
438 	 * - If we're on eDP (using a drm_panel) and the panel is not in a
439 	 *   state where it can respond (it's not powered or it's in a
440 	 *   low power state) then this function may return an error, but
441 	 *   not crash. It's up to the caller of this code to make sure that
442 	 *   the panel is powered on if getting an error back is not OK. If a
443 	 *   drm_panel driver is initiating a DP AUX transfer it may power
444 	 *   itself up however it wants. All other code should ensure that
445 	 *   the pre_enable() bridge chain (which eventually calls the
446 	 *   drm_panel prepare function) has powered the panel.
447 	 */
448 	ssize_t (*transfer)(struct drm_dp_aux *aux,
449 			    struct drm_dp_aux_msg *msg);
450 
451 	/**
452 	 * @wait_hpd_asserted: wait for HPD to be asserted
453 	 *
454 	 * This is mainly useful for eDP panels drivers to wait for an eDP
455 	 * panel to finish powering on. It is optional for DP AUX controllers
456 	 * to implement this function. It is required for DP AUX endpoints
457 	 * (panel drivers) to call this function after powering up but before
458 	 * doing AUX transfers unless the DP AUX endpoint driver knows that
459 	 * we're not using the AUX controller's HPD. One example of the panel
460 	 * driver not needing to call this is if HPD is hooked up to a GPIO
461 	 * that the panel driver can read directly.
462 	 *
463 	 * If a DP AUX controller does not implement this function then it
464 	 * may still support eDP panels that use the AUX controller's built-in
465 	 * HPD signal by implementing a long wait for HPD in the transfer()
466 	 * callback, though this is deprecated.
467 	 *
468 	 * This function will efficiently wait for the HPD signal to be
469 	 * asserted. The `wait_us` parameter that is passed in says that we
470 	 * know that the HPD signal is expected to be asserted within `wait_us`
471 	 * microseconds. This function could wait for longer than `wait_us` if
472 	 * the logic in the DP controller has a long debouncing time. The
473 	 * important thing is that if this function returns success that the
474 	 * DP controller is ready to send AUX transactions.
475 	 *
476 	 * This function returns 0 if HPD was asserted or -ETIMEDOUT if time
477 	 * expired and HPD wasn't asserted. This function should not print
478 	 * timeout errors to the log.
479 	 *
480 	 * The semantics of this function are designed to match the
481 	 * readx_poll_timeout() function. That means a `wait_us` of 0 means
482 	 * to wait forever. Like readx_poll_timeout(), this function may sleep.
483 	 *
484 	 * NOTE: this function specifically reports the state of the HPD pin
485 	 * that's associated with the DP AUX channel. This is different from
486 	 * the HPD concept in much of the rest of DRM which is more about
487 	 * physical presence of a display. For eDP, for instance, a display is
488 	 * assumed always present even if the HPD pin is deasserted.
489 	 */
490 	int (*wait_hpd_asserted)(struct drm_dp_aux *aux, unsigned long wait_us);
491 
492 	/**
493 	 * @i2c_nack_count: Counts I2C NACKs, used for DP validation.
494 	 */
495 	unsigned i2c_nack_count;
496 	/**
497 	 * @i2c_defer_count: Counts I2C DEFERs, used for DP validation.
498 	 */
499 	unsigned i2c_defer_count;
500 	/**
501 	 * @cec: struct containing fields used for CEC-Tunneling-over-AUX.
502 	 */
503 	struct drm_dp_aux_cec cec;
504 	/**
505 	 * @is_remote: Is this AUX CH actually using sideband messaging.
506 	 */
507 	bool is_remote;
508 
509 	/**
510 	 * @powered_down: If true then the remote endpoint is powered down.
511 	 */
512 	bool powered_down;
513 };
514 
515 int drm_dp_dpcd_probe(struct drm_dp_aux *aux, unsigned int offset);
516 void drm_dp_dpcd_set_powered(struct drm_dp_aux *aux, bool powered);
517 ssize_t drm_dp_dpcd_read(struct drm_dp_aux *aux, unsigned int offset,
518 			 void *buffer, size_t size);
519 ssize_t drm_dp_dpcd_write(struct drm_dp_aux *aux, unsigned int offset,
520 			  void *buffer, size_t size);
521 
522 /**
523  * drm_dp_dpcd_readb() - read a single byte from the DPCD
524  * @aux: DisplayPort AUX channel
525  * @offset: address of the register to read
526  * @valuep: location where the value of the register will be stored
527  *
528  * Returns the number of bytes transferred (1) on success, or a negative
529  * error code on failure.
530  */
531 static inline ssize_t drm_dp_dpcd_readb(struct drm_dp_aux *aux,
532 					unsigned int offset, u8 *valuep)
533 {
534 	return drm_dp_dpcd_read(aux, offset, valuep, 1);
535 }
536 
537 /**
538  * drm_dp_dpcd_writeb() - write a single byte to the DPCD
539  * @aux: DisplayPort AUX channel
540  * @offset: address of the register to write
541  * @value: value to write to the register
542  *
543  * Returns the number of bytes transferred (1) on success, or a negative
544  * error code on failure.
545  */
546 static inline ssize_t drm_dp_dpcd_writeb(struct drm_dp_aux *aux,
547 					 unsigned int offset, u8 value)
548 {
549 	return drm_dp_dpcd_write(aux, offset, &value, 1);
550 }
551 
552 int drm_dp_read_dpcd_caps(struct drm_dp_aux *aux,
553 			  u8 dpcd[DP_RECEIVER_CAP_SIZE]);
554 
555 int drm_dp_dpcd_read_link_status(struct drm_dp_aux *aux,
556 				 u8 status[DP_LINK_STATUS_SIZE]);
557 
558 int drm_dp_dpcd_read_phy_link_status(struct drm_dp_aux *aux,
559 				     enum drm_dp_phy dp_phy,
560 				     u8 link_status[DP_LINK_STATUS_SIZE]);
561 
562 bool drm_dp_send_real_edid_checksum(struct drm_dp_aux *aux,
563 				    u8 real_edid_checksum);
564 
565 int drm_dp_read_downstream_info(struct drm_dp_aux *aux,
566 				const u8 dpcd[DP_RECEIVER_CAP_SIZE],
567 				u8 downstream_ports[DP_MAX_DOWNSTREAM_PORTS]);
568 bool drm_dp_downstream_is_type(const u8 dpcd[DP_RECEIVER_CAP_SIZE],
569 			       const u8 port_cap[4], u8 type);
570 bool drm_dp_downstream_is_tmds(const u8 dpcd[DP_RECEIVER_CAP_SIZE],
571 			       const u8 port_cap[4],
572 			       const struct drm_edid *drm_edid);
573 int drm_dp_downstream_max_dotclock(const u8 dpcd[DP_RECEIVER_CAP_SIZE],
574 				   const u8 port_cap[4]);
575 int drm_dp_downstream_max_tmds_clock(const u8 dpcd[DP_RECEIVER_CAP_SIZE],
576 				     const u8 port_cap[4],
577 				     const struct drm_edid *drm_edid);
578 int drm_dp_downstream_min_tmds_clock(const u8 dpcd[DP_RECEIVER_CAP_SIZE],
579 				     const u8 port_cap[4],
580 				     const struct drm_edid *drm_edid);
581 int drm_dp_downstream_max_bpc(const u8 dpcd[DP_RECEIVER_CAP_SIZE],
582 			      const u8 port_cap[4],
583 			      const struct drm_edid *drm_edid);
584 bool drm_dp_downstream_420_passthrough(const u8 dpcd[DP_RECEIVER_CAP_SIZE],
585 				       const u8 port_cap[4]);
586 bool drm_dp_downstream_444_to_420_conversion(const u8 dpcd[DP_RECEIVER_CAP_SIZE],
587 					     const u8 port_cap[4]);
588 struct drm_display_mode *drm_dp_downstream_mode(struct drm_device *dev,
589 						const u8 dpcd[DP_RECEIVER_CAP_SIZE],
590 						const u8 port_cap[4]);
591 int drm_dp_downstream_id(struct drm_dp_aux *aux, char id[6]);
592 void drm_dp_downstream_debug(struct seq_file *m,
593 			     const u8 dpcd[DP_RECEIVER_CAP_SIZE],
594 			     const u8 port_cap[4],
595 			     const struct drm_edid *drm_edid,
596 			     struct drm_dp_aux *aux);
597 enum drm_mode_subconnector
598 drm_dp_subconnector_type(const u8 dpcd[DP_RECEIVER_CAP_SIZE],
599 			 const u8 port_cap[4]);
600 void drm_dp_set_subconnector_property(struct drm_connector *connector,
601 				      enum drm_connector_status status,
602 				      const u8 *dpcd,
603 				      const u8 port_cap[4]);
604 
605 struct drm_dp_desc;
606 bool drm_dp_read_sink_count_cap(struct drm_connector *connector,
607 				const u8 dpcd[DP_RECEIVER_CAP_SIZE],
608 				const struct drm_dp_desc *desc);
609 int drm_dp_read_sink_count(struct drm_dp_aux *aux);
610 
611 int drm_dp_read_lttpr_common_caps(struct drm_dp_aux *aux,
612 				  const u8 dpcd[DP_RECEIVER_CAP_SIZE],
613 				  u8 caps[DP_LTTPR_COMMON_CAP_SIZE]);
614 int drm_dp_read_lttpr_phy_caps(struct drm_dp_aux *aux,
615 			       const u8 dpcd[DP_RECEIVER_CAP_SIZE],
616 			       enum drm_dp_phy dp_phy,
617 			       u8 caps[DP_LTTPR_PHY_CAP_SIZE]);
618 int drm_dp_lttpr_count(const u8 cap[DP_LTTPR_COMMON_CAP_SIZE]);
619 int drm_dp_lttpr_max_link_rate(const u8 caps[DP_LTTPR_COMMON_CAP_SIZE]);
620 int drm_dp_lttpr_max_lane_count(const u8 caps[DP_LTTPR_COMMON_CAP_SIZE]);
621 bool drm_dp_lttpr_voltage_swing_level_3_supported(const u8 caps[DP_LTTPR_PHY_CAP_SIZE]);
622 bool drm_dp_lttpr_pre_emphasis_level_3_supported(const u8 caps[DP_LTTPR_PHY_CAP_SIZE]);
623 
624 void drm_dp_remote_aux_init(struct drm_dp_aux *aux);
625 void drm_dp_aux_init(struct drm_dp_aux *aux);
626 int drm_dp_aux_register(struct drm_dp_aux *aux);
627 void drm_dp_aux_unregister(struct drm_dp_aux *aux);
628 
629 int drm_dp_start_crc(struct drm_dp_aux *aux, struct drm_crtc *crtc);
630 int drm_dp_stop_crc(struct drm_dp_aux *aux);
631 
632 struct drm_dp_dpcd_ident {
633 	u8 oui[3];
634 	u8 device_id[6];
635 	u8 hw_rev;
636 	u8 sw_major_rev;
637 	u8 sw_minor_rev;
638 } __packed;
639 
640 /**
641  * struct drm_dp_desc - DP branch/sink device descriptor
642  * @ident: DP device identification from DPCD 0x400 (sink) or 0x500 (branch).
643  * @quirks: Quirks; use drm_dp_has_quirk() to query for the quirks.
644  */
645 struct drm_dp_desc {
646 	struct drm_dp_dpcd_ident ident;
647 	u32 quirks;
648 };
649 
650 int drm_dp_read_desc(struct drm_dp_aux *aux, struct drm_dp_desc *desc,
651 		     bool is_branch);
652 
653 /**
654  * enum drm_dp_quirk - Display Port sink/branch device specific quirks
655  *
656  * Display Port sink and branch devices in the wild have a variety of bugs, try
657  * to collect them here. The quirks are shared, but it's up to the drivers to
658  * implement workarounds for them.
659  */
660 enum drm_dp_quirk {
661 	/**
662 	 * @DP_DPCD_QUIRK_CONSTANT_N:
663 	 *
664 	 * The device requires main link attributes Mvid and Nvid to be limited
665 	 * to 16 bits. So will give a constant value (0x8000) for compatability.
666 	 */
667 	DP_DPCD_QUIRK_CONSTANT_N,
668 	/**
669 	 * @DP_DPCD_QUIRK_NO_PSR:
670 	 *
671 	 * The device does not support PSR even if reports that it supports or
672 	 * driver still need to implement proper handling for such device.
673 	 */
674 	DP_DPCD_QUIRK_NO_PSR,
675 	/**
676 	 * @DP_DPCD_QUIRK_NO_SINK_COUNT:
677 	 *
678 	 * The device does not set SINK_COUNT to a non-zero value.
679 	 * The driver should ignore SINK_COUNT during detection. Note that
680 	 * drm_dp_read_sink_count_cap() automatically checks for this quirk.
681 	 */
682 	DP_DPCD_QUIRK_NO_SINK_COUNT,
683 	/**
684 	 * @DP_DPCD_QUIRK_DSC_WITHOUT_VIRTUAL_DPCD:
685 	 *
686 	 * The device supports MST DSC despite not supporting Virtual DPCD.
687 	 * The DSC caps can be read from the physical aux instead.
688 	 */
689 	DP_DPCD_QUIRK_DSC_WITHOUT_VIRTUAL_DPCD,
690 	/**
691 	 * @DP_DPCD_QUIRK_CAN_DO_MAX_LINK_RATE_3_24_GBPS:
692 	 *
693 	 * The device supports a link rate of 3.24 Gbps (multiplier 0xc) despite
694 	 * the DP_MAX_LINK_RATE register reporting a lower max multiplier.
695 	 */
696 	DP_DPCD_QUIRK_CAN_DO_MAX_LINK_RATE_3_24_GBPS,
697 	/**
698 	 * @DP_DPCD_QUIRK_HBLANK_EXPANSION_REQUIRES_DSC:
699 	 *
700 	 * The device applies HBLANK expansion for some modes, but this
701 	 * requires enabling DSC.
702 	 */
703 	DP_DPCD_QUIRK_HBLANK_EXPANSION_REQUIRES_DSC,
704 };
705 
706 /**
707  * drm_dp_has_quirk() - does the DP device have a specific quirk
708  * @desc: Device descriptor filled by drm_dp_read_desc()
709  * @quirk: Quirk to query for
710  *
711  * Return true if DP device identified by @desc has @quirk.
712  */
713 static inline bool
714 drm_dp_has_quirk(const struct drm_dp_desc *desc, enum drm_dp_quirk quirk)
715 {
716 	return desc->quirks & BIT(quirk);
717 }
718 
719 /**
720  * struct drm_edp_backlight_info - Probed eDP backlight info struct
721  * @pwmgen_bit_count: The pwmgen bit count
722  * @pwm_freq_pre_divider: The PWM frequency pre-divider value being used for this backlight, if any
723  * @max: The maximum backlight level that may be set
724  * @lsb_reg_used: Do we also write values to the DP_EDP_BACKLIGHT_BRIGHTNESS_LSB register?
725  * @aux_enable: Does the panel support the AUX enable cap?
726  * @aux_set: Does the panel support setting the brightness through AUX?
727  *
728  * This structure contains various data about an eDP backlight, which can be populated by using
729  * drm_edp_backlight_init().
730  */
731 struct drm_edp_backlight_info {
732 	u8 pwmgen_bit_count;
733 	u8 pwm_freq_pre_divider;
734 	u16 max;
735 
736 	bool lsb_reg_used : 1;
737 	bool aux_enable : 1;
738 	bool aux_set : 1;
739 };
740 
741 int
742 drm_edp_backlight_init(struct drm_dp_aux *aux, struct drm_edp_backlight_info *bl,
743 		       u16 driver_pwm_freq_hz, const u8 edp_dpcd[EDP_DISPLAY_CTL_CAP_SIZE],
744 		       u16 *current_level, u8 *current_mode);
745 int drm_edp_backlight_set_level(struct drm_dp_aux *aux, const struct drm_edp_backlight_info *bl,
746 				u16 level);
747 int drm_edp_backlight_enable(struct drm_dp_aux *aux, const struct drm_edp_backlight_info *bl,
748 			     u16 level);
749 int drm_edp_backlight_disable(struct drm_dp_aux *aux, const struct drm_edp_backlight_info *bl);
750 
751 #if IS_ENABLED(CONFIG_DRM_KMS_HELPER) && (IS_BUILTIN(CONFIG_BACKLIGHT_CLASS_DEVICE) || \
752 	(IS_MODULE(CONFIG_DRM_KMS_HELPER) && IS_MODULE(CONFIG_BACKLIGHT_CLASS_DEVICE)))
753 
754 int drm_panel_dp_aux_backlight(struct drm_panel *panel, struct drm_dp_aux *aux);
755 
756 #else
757 
758 static inline int drm_panel_dp_aux_backlight(struct drm_panel *panel,
759 					     struct drm_dp_aux *aux)
760 {
761 	return 0;
762 }
763 
764 #endif
765 
766 #ifdef CONFIG_DRM_DISPLAY_DP_AUX_CEC
767 void drm_dp_cec_irq(struct drm_dp_aux *aux);
768 void drm_dp_cec_register_connector(struct drm_dp_aux *aux,
769 				   struct drm_connector *connector);
770 void drm_dp_cec_unregister_connector(struct drm_dp_aux *aux);
771 void drm_dp_cec_attach(struct drm_dp_aux *aux, u16 source_physical_address);
772 void drm_dp_cec_set_edid(struct drm_dp_aux *aux, const struct edid *edid);
773 void drm_dp_cec_unset_edid(struct drm_dp_aux *aux);
774 #else
775 static inline void drm_dp_cec_irq(struct drm_dp_aux *aux)
776 {
777 }
778 
779 static inline void
780 drm_dp_cec_register_connector(struct drm_dp_aux *aux,
781 			      struct drm_connector *connector)
782 {
783 }
784 
785 static inline void drm_dp_cec_unregister_connector(struct drm_dp_aux *aux)
786 {
787 }
788 
789 static inline void drm_dp_cec_attach(struct drm_dp_aux *aux,
790 				     u16 source_physical_address)
791 {
792 }
793 
794 static inline void drm_dp_cec_set_edid(struct drm_dp_aux *aux,
795 				       const struct edid *edid)
796 {
797 }
798 
799 static inline void drm_dp_cec_unset_edid(struct drm_dp_aux *aux)
800 {
801 }
802 
803 #endif
804 
805 /**
806  * struct drm_dp_phy_test_params - DP Phy Compliance parameters
807  * @link_rate: Requested Link rate from DPCD 0x219
808  * @num_lanes: Number of lanes requested by sing through DPCD 0x220
809  * @phy_pattern: DP Phy test pattern from DPCD 0x248
810  * @hbr2_reset: DP HBR2_COMPLIANCE_SCRAMBLER_RESET from DCPD 0x24A and 0x24B
811  * @custom80: DP Test_80BIT_CUSTOM_PATTERN from DPCDs 0x250 through 0x259
812  * @enhanced_frame_cap: flag for enhanced frame capability.
813  */
814 struct drm_dp_phy_test_params {
815 	int link_rate;
816 	u8 num_lanes;
817 	u8 phy_pattern;
818 	u8 hbr2_reset[2];
819 	u8 custom80[10];
820 	bool enhanced_frame_cap;
821 };
822 
823 int drm_dp_get_phy_test_pattern(struct drm_dp_aux *aux,
824 				struct drm_dp_phy_test_params *data);
825 int drm_dp_set_phy_test_pattern(struct drm_dp_aux *aux,
826 				struct drm_dp_phy_test_params *data, u8 dp_rev);
827 int drm_dp_get_pcon_max_frl_bw(const u8 dpcd[DP_RECEIVER_CAP_SIZE],
828 			       const u8 port_cap[4]);
829 int drm_dp_pcon_frl_prepare(struct drm_dp_aux *aux, bool enable_frl_ready_hpd);
830 bool drm_dp_pcon_is_frl_ready(struct drm_dp_aux *aux);
831 int drm_dp_pcon_frl_configure_1(struct drm_dp_aux *aux, int max_frl_gbps,
832 				u8 frl_mode);
833 int drm_dp_pcon_frl_configure_2(struct drm_dp_aux *aux, int max_frl_mask,
834 				u8 frl_type);
835 int drm_dp_pcon_reset_frl_config(struct drm_dp_aux *aux);
836 int drm_dp_pcon_frl_enable(struct drm_dp_aux *aux);
837 
838 bool drm_dp_pcon_hdmi_link_active(struct drm_dp_aux *aux);
839 int drm_dp_pcon_hdmi_link_mode(struct drm_dp_aux *aux, u8 *frl_trained_mask);
840 void drm_dp_pcon_hdmi_frl_link_error_count(struct drm_dp_aux *aux,
841 					   struct drm_connector *connector);
842 bool drm_dp_pcon_enc_is_dsc_1_2(const u8 pcon_dsc_dpcd[DP_PCON_DSC_ENCODER_CAP_SIZE]);
843 int drm_dp_pcon_dsc_max_slices(const u8 pcon_dsc_dpcd[DP_PCON_DSC_ENCODER_CAP_SIZE]);
844 int drm_dp_pcon_dsc_max_slice_width(const u8 pcon_dsc_dpcd[DP_PCON_DSC_ENCODER_CAP_SIZE]);
845 int drm_dp_pcon_dsc_bpp_incr(const u8 pcon_dsc_dpcd[DP_PCON_DSC_ENCODER_CAP_SIZE]);
846 int drm_dp_pcon_pps_default(struct drm_dp_aux *aux);
847 int drm_dp_pcon_pps_override_buf(struct drm_dp_aux *aux, u8 pps_buf[128]);
848 int drm_dp_pcon_pps_override_param(struct drm_dp_aux *aux, u8 pps_param[6]);
849 bool drm_dp_downstream_rgb_to_ycbcr_conversion(const u8 dpcd[DP_RECEIVER_CAP_SIZE],
850 					       const u8 port_cap[4], u8 color_spc);
851 int drm_dp_pcon_convert_rgb_to_ycbcr(struct drm_dp_aux *aux, u8 color_spc);
852 
853 #define DRM_DP_BW_OVERHEAD_MST		BIT(0)
854 #define DRM_DP_BW_OVERHEAD_UHBR		BIT(1)
855 #define DRM_DP_BW_OVERHEAD_SSC_REF_CLK	BIT(2)
856 #define DRM_DP_BW_OVERHEAD_FEC		BIT(3)
857 #define DRM_DP_BW_OVERHEAD_DSC		BIT(4)
858 
859 int drm_dp_bw_overhead(int lane_count, int hactive,
860 		       int dsc_slice_count,
861 		       int bpp_x16, unsigned long flags);
862 int drm_dp_bw_channel_coding_efficiency(bool is_uhbr);
863 int drm_dp_max_dprx_data_rate(int max_link_rate, int max_lanes);
864 
865 ssize_t drm_dp_vsc_sdp_pack(const struct drm_dp_vsc_sdp *vsc, struct dp_sdp *sdp);
866 
867 #endif /* _DRM_DP_HELPER_H_ */
868