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1/*
2 * Copyright © 2008-2015 Intel Corporation
3 *
4 * Permission is hereby granted, free of charge, to any person obtaining a
5 * copy of this software and associated documentation files (the "Software"),
6 * to deal in the Software without restriction, including without limitation
7 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
8 * and/or sell copies of the Software, and to permit persons to whom the
9 * Software is furnished to do so, subject to the following conditions:
10 *
11 * The above copyright notice and this permission notice (including the next
12 * paragraph) shall be included in all copies or substantial portions of the
13 * Software.
14 *
15 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
16 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
17 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
18 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
19 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
20 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
21 * IN THE SOFTWARE.
22 */
23
24#include "intel_display_types.h"
25#include "intel_dp.h"
26#include "intel_dp_link_training.h"
27
28static void
29intel_dp_dump_link_status(const u8 link_status[DP_LINK_STATUS_SIZE])
30{
31
32 DRM_DEBUG_KMS("ln0_1:0x%x ln2_3:0x%x align:0x%x sink:0x%x adj_req0_1:0x%x adj_req2_3:0x%x",
33 link_status[0], link_status[1], link_status[2],
34 link_status[3], link_status[4], link_status[5]);
35}
36
37static void
38intel_get_adjust_train(struct intel_dp *intel_dp,
39 const u8 link_status[DP_LINK_STATUS_SIZE])
40{
41 u8 v = 0;
42 u8 p = 0;
43 int lane;
44 u8 voltage_max;
45 u8 preemph_max;
46
47 for (lane = 0; lane < intel_dp->lane_count; lane++) {
48 u8 this_v = drm_dp_get_adjust_request_voltage(link_status, lane);
49 u8 this_p = drm_dp_get_adjust_request_pre_emphasis(link_status, lane);
50
51 if (this_v > v)
52 v = this_v;
53 if (this_p > p)
54 p = this_p;
55 }
56
57 voltage_max = intel_dp_voltage_max(intel_dp);
58 if (v >= voltage_max)
59 v = voltage_max | DP_TRAIN_MAX_SWING_REACHED;
60
61 preemph_max = intel_dp_pre_emphasis_max(intel_dp, v);
62 if (p >= preemph_max)
63 p = preemph_max | DP_TRAIN_MAX_PRE_EMPHASIS_REACHED;
64
65 for (lane = 0; lane < 4; lane++)
66 intel_dp->train_set[lane] = v | p;
67}
68
69static bool
70intel_dp_set_link_train(struct intel_dp *intel_dp,
71 u8 dp_train_pat)
72{
73 u8 buf[sizeof(intel_dp->train_set) + 1];
74 int ret, len;
75
76 intel_dp_program_link_training_pattern(intel_dp, dp_train_pat);
77
78 buf[0] = dp_train_pat;
79 if ((dp_train_pat & DP_TRAINING_PATTERN_MASK) ==
80 DP_TRAINING_PATTERN_DISABLE) {
81 /* don't write DP_TRAINING_LANEx_SET on disable */
82 len = 1;
83 } else {
84 /* DP_TRAINING_LANEx_SET follow DP_TRAINING_PATTERN_SET */
85 memcpy(buf + 1, intel_dp->train_set, intel_dp->lane_count);
86 len = intel_dp->lane_count + 1;
87 }
88
89 ret = drm_dp_dpcd_write(&intel_dp->aux, DP_TRAINING_PATTERN_SET,
90 buf, len);
91
92 return ret == len;
93}
94
95static bool
96intel_dp_reset_link_train(struct intel_dp *intel_dp,
97 u8 dp_train_pat)
98{
99 memset(intel_dp->train_set, 0, sizeof(intel_dp->train_set));
100 intel_dp_set_signal_levels(intel_dp);
101 return intel_dp_set_link_train(intel_dp, dp_train_pat);
102}
103
104static bool
105intel_dp_update_link_train(struct intel_dp *intel_dp)
106{
107 int ret;
108
109 intel_dp_set_signal_levels(intel_dp);
110
111 ret = drm_dp_dpcd_write(&intel_dp->aux, DP_TRAINING_LANE0_SET,
112 intel_dp->train_set, intel_dp->lane_count);
113
114 return ret == intel_dp->lane_count;
115}
116
117static bool intel_dp_link_max_vswing_reached(struct intel_dp *intel_dp)
118{
119 int lane;
120
121 for (lane = 0; lane < intel_dp->lane_count; lane++)
122 if ((intel_dp->train_set[lane] &
123 DP_TRAIN_MAX_SWING_REACHED) == 0)
124 return false;
125
126 return true;
127}
128
129/* Enable corresponding port and start training pattern 1 */
130static bool
131intel_dp_link_training_clock_recovery(struct intel_dp *intel_dp)
132{
133 u8 voltage;
134 int voltage_tries, cr_tries, max_cr_tries;
135 bool max_vswing_reached = false;
136 u8 link_config[2];
137 u8 link_bw, rate_select;
138
139 if (intel_dp->prepare_link_retrain)
140 intel_dp->prepare_link_retrain(intel_dp);
141
142 intel_dp_compute_rate(intel_dp, intel_dp->link_rate,
143 &link_bw, &rate_select);
144
145 if (link_bw)
146 DRM_DEBUG_KMS("Using LINK_BW_SET value %02x\n", link_bw);
147 else
148 DRM_DEBUG_KMS("Using LINK_RATE_SET value %02x\n", rate_select);
149
150 /* Write the link configuration data */
151 link_config[0] = link_bw;
152 link_config[1] = intel_dp->lane_count;
153 if (drm_dp_enhanced_frame_cap(intel_dp->dpcd))
154 link_config[1] |= DP_LANE_COUNT_ENHANCED_FRAME_EN;
155 drm_dp_dpcd_write(&intel_dp->aux, DP_LINK_BW_SET, link_config, 2);
156
157 /* eDP 1.4 rate select method. */
158 if (!link_bw)
159 drm_dp_dpcd_write(&intel_dp->aux, DP_LINK_RATE_SET,
160 &rate_select, 1);
161
162 link_config[0] = 0;
163 link_config[1] = DP_SET_ANSI_8B10B;
164 drm_dp_dpcd_write(&intel_dp->aux, DP_DOWNSPREAD_CTRL, link_config, 2);
165
166 intel_dp->DP |= DP_PORT_EN;
167
168 /* clock recovery */
169 if (!intel_dp_reset_link_train(intel_dp,
170 DP_TRAINING_PATTERN_1 |
171 DP_LINK_SCRAMBLING_DISABLE)) {
172 DRM_ERROR("failed to enable link training\n");
173 return false;
174 }
175
176 /*
177 * The DP 1.4 spec defines the max clock recovery retries value
178 * as 10 but for pre-DP 1.4 devices we set a very tolerant
179 * retry limit of 80 (4 voltage levels x 4 preemphasis levels x
180 * x 5 identical voltage retries). Since the previous specs didn't
181 * define a limit and created the possibility of an infinite loop
182 * we want to prevent any sync from triggering that corner case.
183 */
184 if (intel_dp->dpcd[DP_DPCD_REV] >= DP_DPCD_REV_14)
185 max_cr_tries = 10;
186 else
187 max_cr_tries = 80;
188
189 voltage_tries = 1;
190 for (cr_tries = 0; cr_tries < max_cr_tries; ++cr_tries) {
191 u8 link_status[DP_LINK_STATUS_SIZE];
192
193 drm_dp_link_train_clock_recovery_delay(intel_dp->dpcd);
194
195 if (!intel_dp_get_link_status(intel_dp, link_status)) {
196 DRM_ERROR("failed to get link status\n");
197 return false;
198 }
199
200 if (drm_dp_clock_recovery_ok(link_status, intel_dp->lane_count)) {
201 DRM_DEBUG_KMS("clock recovery OK\n");
202 return true;
203 }
204
205 if (voltage_tries == 5) {
206 DRM_DEBUG_KMS("Same voltage tried 5 times\n");
207 return false;
208 }
209
210 if (max_vswing_reached) {
211 DRM_DEBUG_KMS("Max Voltage Swing reached\n");
212 return false;
213 }
214
215 voltage = intel_dp->train_set[0] & DP_TRAIN_VOLTAGE_SWING_MASK;
216
217 /* Update training set as requested by target */
218 intel_get_adjust_train(intel_dp, link_status);
219 if (!intel_dp_update_link_train(intel_dp)) {
220 DRM_ERROR("failed to update link training\n");
221 return false;
222 }
223
224 if ((intel_dp->train_set[0] & DP_TRAIN_VOLTAGE_SWING_MASK) ==
225 voltage)
226 ++voltage_tries;
227 else
228 voltage_tries = 1;
229
230 if (intel_dp_link_max_vswing_reached(intel_dp))
231 max_vswing_reached = true;
232
233 }
234 DRM_ERROR("Failed clock recovery %d times, giving up!\n", max_cr_tries);
235 return false;
236}
237
238/*
239 * Pick training pattern for channel equalization. Training pattern 4 for HBR3
240 * or for 1.4 devices that support it, training Pattern 3 for HBR2
241 * or 1.2 devices that support it, Training Pattern 2 otherwise.
242 */
243static u32 intel_dp_training_pattern(struct intel_dp *intel_dp)
244{
245 bool source_tps3, sink_tps3, source_tps4, sink_tps4;
246
247 /*
248 * Intel platforms that support HBR3 also support TPS4. It is mandatory
249 * for all downstream devices that support HBR3. There are no known eDP
250 * panels that support TPS4 as of Feb 2018 as per VESA eDP_v1.4b_E1
251 * specification.
252 */
253 source_tps4 = intel_dp_source_supports_hbr3(intel_dp);
254 sink_tps4 = drm_dp_tps4_supported(intel_dp->dpcd);
255 if (source_tps4 && sink_tps4) {
256 return DP_TRAINING_PATTERN_4;
257 } else if (intel_dp->link_rate == 810000) {
258 if (!source_tps4)
259 DRM_DEBUG_KMS("8.1 Gbps link rate without source HBR3/TPS4 support\n");
260 if (!sink_tps4)
261 DRM_DEBUG_KMS("8.1 Gbps link rate without sink TPS4 support\n");
262 }
263 /*
264 * Intel platforms that support HBR2 also support TPS3. TPS3 support is
265 * also mandatory for downstream devices that support HBR2. However, not
266 * all sinks follow the spec.
267 */
268 source_tps3 = intel_dp_source_supports_hbr2(intel_dp);
269 sink_tps3 = drm_dp_tps3_supported(intel_dp->dpcd);
270 if (source_tps3 && sink_tps3) {
271 return DP_TRAINING_PATTERN_3;
272 } else if (intel_dp->link_rate >= 540000) {
273 if (!source_tps3)
274 DRM_DEBUG_KMS(">=5.4/6.48 Gbps link rate without source HBR2/TPS3 support\n");
275 if (!sink_tps3)
276 DRM_DEBUG_KMS(">=5.4/6.48 Gbps link rate without sink TPS3 support\n");
277 }
278
279 return DP_TRAINING_PATTERN_2;
280}
281
282static bool
283intel_dp_link_training_channel_equalization(struct intel_dp *intel_dp)
284{
285 int tries;
286 u32 training_pattern;
287 u8 link_status[DP_LINK_STATUS_SIZE];
288 bool channel_eq = false;
289
290 training_pattern = intel_dp_training_pattern(intel_dp);
291 /* Scrambling is disabled for TPS2/3 and enabled for TPS4 */
292 if (training_pattern != DP_TRAINING_PATTERN_4)
293 training_pattern |= DP_LINK_SCRAMBLING_DISABLE;
294
295 /* channel equalization */
296 if (!intel_dp_set_link_train(intel_dp,
297 training_pattern)) {
298 DRM_ERROR("failed to start channel equalization\n");
299 return false;
300 }
301
302 for (tries = 0; tries < 5; tries++) {
303
304 drm_dp_link_train_channel_eq_delay(intel_dp->dpcd);
305 if (!intel_dp_get_link_status(intel_dp, link_status)) {
306 DRM_ERROR("failed to get link status\n");
307 break;
308 }
309
310 /* Make sure clock is still ok */
311 if (!drm_dp_clock_recovery_ok(link_status,
312 intel_dp->lane_count)) {
313 intel_dp_dump_link_status(link_status);
314 DRM_DEBUG_KMS("Clock recovery check failed, cannot "
315 "continue channel equalization\n");
316 break;
317 }
318
319 if (drm_dp_channel_eq_ok(link_status,
320 intel_dp->lane_count)) {
321 channel_eq = true;
322 DRM_DEBUG_KMS("Channel EQ done. DP Training "
323 "successful\n");
324 break;
325 }
326
327 /* Update training set as requested by target */
328 intel_get_adjust_train(intel_dp, link_status);
329 if (!intel_dp_update_link_train(intel_dp)) {
330 DRM_ERROR("failed to update link training\n");
331 break;
332 }
333 }
334
335 /* Try 5 times, else fail and try at lower BW */
336 if (tries == 5) {
337 intel_dp_dump_link_status(link_status);
338 DRM_DEBUG_KMS("Channel equalization failed 5 times\n");
339 }
340
341 intel_dp_set_idle_link_train(intel_dp);
342
343 return channel_eq;
344
345}
346
347void intel_dp_stop_link_train(struct intel_dp *intel_dp)
348{
349 intel_dp->link_trained = true;
350
351 intel_dp_set_link_train(intel_dp,
352 DP_TRAINING_PATTERN_DISABLE);
353}
354
355void
356intel_dp_start_link_train(struct intel_dp *intel_dp)
357{
358 struct intel_connector *intel_connector = intel_dp->attached_connector;
359
360 if (!intel_dp_link_training_clock_recovery(intel_dp))
361 goto failure_handling;
362 if (!intel_dp_link_training_channel_equalization(intel_dp))
363 goto failure_handling;
364
365 DRM_DEBUG_KMS("[CONNECTOR:%d:%s] Link Training Passed at Link Rate = %d, Lane count = %d",
366 intel_connector->base.base.id,
367 intel_connector->base.name,
368 intel_dp->link_rate, intel_dp->lane_count);
369 return;
370
371 failure_handling:
372 DRM_DEBUG_KMS("[CONNECTOR:%d:%s] Link Training failed at link rate = %d, lane count = %d",
373 intel_connector->base.base.id,
374 intel_connector->base.name,
375 intel_dp->link_rate, intel_dp->lane_count);
376 if (!intel_dp_get_link_train_fallback_values(intel_dp,
377 intel_dp->link_rate,
378 intel_dp->lane_count))
379 /* Schedule a Hotplug Uevent to userspace to start modeset */
380 schedule_work(&intel_connector->modeset_retry_work);
381 return;
382}