/*
* Copyright © 2008-2015 Intel Corporation
*
* Permission is hereby granted, free of charge, to any person obtaining a
* copy of this software and associated documentation files (the "Software"),
* to deal in the Software without restriction, including without limitation
* the rights to use, copy, modify, merge, publish, distribute, sublicense,
* and/or sell copies of the Software, and to permit persons to whom the
* Software is furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice (including the next
* paragraph) shall be included in all copies or substantial portions of the
* Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
* IN THE SOFTWARE.
*/
#include "intel_dp.h"
#include "intel_dp_link_training.h"
#include "intel_drv.h"
static void
intel_dp_dump_link_status(const u8 link_status[DP_LINK_STATUS_SIZE])
{
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",
link_status[0], link_status[1], link_status[2],
link_status[3], link_status[4], link_status[5]);
}
static void
intel_get_adjust_train(struct intel_dp *intel_dp,
const u8 link_status[DP_LINK_STATUS_SIZE])
{
u8 v = 0;
u8 p = 0;
int lane;
u8 voltage_max;
u8 preemph_max;
for (lane = 0; lane < intel_dp->lane_count; lane++) {
u8 this_v = drm_dp_get_adjust_request_voltage(link_status, lane);
u8 this_p = drm_dp_get_adjust_request_pre_emphasis(link_status, lane);
if (this_v > v)
v = this_v;
if (this_p > p)
p = this_p;
}
voltage_max = intel_dp_voltage_max(intel_dp);
if (v >= voltage_max)
v = voltage_max | DP_TRAIN_MAX_SWING_REACHED;
preemph_max = intel_dp_pre_emphasis_max(intel_dp, v);
if (p >= preemph_max)
p = preemph_max | DP_TRAIN_MAX_PRE_EMPHASIS_REACHED;
for (lane = 0; lane < 4; lane++)
intel_dp->train_set[lane] = v | p;
}
static bool
intel_dp_set_link_train(struct intel_dp *intel_dp,
u8 dp_train_pat)
{
u8 buf[sizeof(intel_dp->train_set) + 1];
int ret, len;
intel_dp_program_link_training_pattern(intel_dp, dp_train_pat);
buf[0] = dp_train_pat;
if ((dp_train_pat & DP_TRAINING_PATTERN_MASK) ==
DP_TRAINING_PATTERN_DISABLE) {
/* don't write DP_TRAINING_LANEx_SET on disable */
len = 1;
} else {
/* DP_TRAINING_LANEx_SET follow DP_TRAINING_PATTERN_SET */
memcpy(buf + 1, intel_dp->train_set, intel_dp->lane_count);
len = intel_dp->lane_count + 1;
}
ret = drm_dp_dpcd_write(&intel_dp->aux, DP_TRAINING_PATTERN_SET,
buf, len);
return ret == len;
}
static bool
intel_dp_reset_link_train(struct intel_dp *intel_dp,
u8 dp_train_pat)
{
memset(intel_dp->train_set, 0, sizeof(intel_dp->train_set));
intel_dp_set_signal_levels(intel_dp);
return intel_dp_set_link_train(intel_dp, dp_train_pat);
}
static bool
intel_dp_update_link_train(struct intel_dp *intel_dp)
{
int ret;
intel_dp_set_signal_levels(intel_dp);
ret = drm_dp_dpcd_write(&intel_dp->aux, DP_TRAINING_LANE0_SET,
intel_dp->train_set, intel_dp->lane_count);
return ret == intel_dp->lane_count;
}
static bool intel_dp_link_max_vswing_reached(struct intel_dp *intel_dp)
{
int lane;
for (lane = 0; lane < intel_dp->lane_count; lane++)
if ((intel_dp->train_set[lane] &
DP_TRAIN_MAX_SWING_REACHED) == 0)
return false;
return true;
}
/* Enable corresponding port and start training pattern 1 */
static bool
intel_dp_link_training_clock_recovery(struct intel_dp *intel_dp)
{
u8 voltage;
int voltage_tries, cr_tries, max_cr_tries;
bool max_vswing_reached = false;
u8 link_config[2];
u8 link_bw, rate_select;
if (intel_dp->prepare_link_retrain)
intel_dp->prepare_link_retrain(intel_dp);
intel_dp_compute_rate(intel_dp, intel_dp->link_rate,
&link_bw, &rate_select);
if (link_bw)
DRM_DEBUG_KMS("Using LINK_BW_SET value %02x\n", link_bw);
else
DRM_DEBUG_KMS("Using LINK_RATE_SET value %02x\n", rate_select);
/* Write the link configuration data */
link_config[0] = link_bw;
link_config[1] = intel_dp->lane_count;
if (drm_dp_enhanced_frame_cap(intel_dp->dpcd))
link_config[1] |= DP_LANE_COUNT_ENHANCED_FRAME_EN;
drm_dp_dpcd_write(&intel_dp->aux, DP_LINK_BW_SET, link_config, 2);
/* eDP 1.4 rate select method. */
if (!link_bw)
drm_dp_dpcd_write(&intel_dp->aux, DP_LINK_RATE_SET,
&rate_select, 1);
link_config[0] = 0;
link_config[1] = DP_SET_ANSI_8B10B;
drm_dp_dpcd_write(&intel_dp->aux, DP_DOWNSPREAD_CTRL, link_config, 2);
intel_dp->DP |= DP_PORT_EN;
/* clock recovery */
if (!intel_dp_reset_link_train(intel_dp,
DP_TRAINING_PATTERN_1 |
DP_LINK_SCRAMBLING_DISABLE)) {
DRM_ERROR("failed to enable link training\n");
return false;
}
/*
* The DP 1.4 spec defines the max clock recovery retries value
* as 10 but for pre-DP 1.4 devices we set a very tolerant
* retry limit of 80 (4 voltage levels x 4 preemphasis levels x
* x 5 identical voltage retries). Since the previous specs didn't
* define a limit and created the possibility of an infinite loop
* we want to prevent any sync from triggering that corner case.
*/
if (intel_dp->dpcd[DP_DPCD_REV] >= DP_DPCD_REV_14)
max_cr_tries = 10;
else
max_cr_tries = 80;
voltage_tries = 1;
for (cr_tries = 0; cr_tries < max_cr_tries; ++cr_tries) {
u8 link_status[DP_LINK_STATUS_SIZE];
drm_dp_link_train_clock_recovery_delay(intel_dp->dpcd);
if (!intel_dp_get_link_status(intel_dp, link_status)) {
DRM_ERROR("failed to get link status\n");
return false;
}
if (drm_dp_clock_recovery_ok(link_status, intel_dp->lane_count)) {
DRM_DEBUG_KMS("clock recovery OK\n");
return true;
}
if (voltage_tries == 5) {
DRM_DEBUG_KMS("Same voltage tried 5 times\n");
return false;
}
if (max_vswing_reached) {
DRM_DEBUG_KMS("Max Voltage Swing reached\n");
return false;
}
voltage = intel_dp->train_set[0] & DP_TRAIN_VOLTAGE_SWING_MASK;
/* Update training set as requested by target */
intel_get_adjust_train(intel_dp, link_status);
if (!intel_dp_update_link_train(intel_dp)) {
DRM_ERROR("failed to update link training\n");
return false;
}
if ((intel_dp->train_set[0] & DP_TRAIN_VOLTAGE_SWING_MASK) ==
voltage)
++voltage_tries;
else
voltage_tries = 1;
if (intel_dp_link_max_vswing_reached(intel_dp))
max_vswing_reached = true;
}
DRM_ERROR("Failed clock recovery %d times, giving up!\n", max_cr_tries);
return false;
}
/*
* Pick training pattern for channel equalization. Training pattern 4 for HBR3
* or for 1.4 devices that support it, training Pattern 3 for HBR2
* or 1.2 devices that support it, Training Pattern 2 otherwise.
*/
static u32 intel_dp_training_pattern(struct intel_dp *intel_dp)
{
bool source_tps3, sink_tps3, source_tps4, sink_tps4;
/*
* Intel platforms that support HBR3 also support TPS4. It is mandatory
* for all downstream devices that support HBR3. There are no known eDP
* panels that support TPS4 as of Feb 2018 as per VESA eDP_v1.4b_E1
* specification.
*/
source_tps4 = intel_dp_source_supports_hbr3(intel_dp);
sink_tps4 = drm_dp_tps4_supported(intel_dp->dpcd);
if (source_tps4 && sink_tps4) {
return DP_TRAINING_PATTERN_4;
} else if (intel_dp->link_rate == 810000) {
if (!source_tps4)
DRM_DEBUG_KMS("8.1 Gbps link rate without source HBR3/TPS4 support\n");
if (!sink_tps4)
DRM_DEBUG_KMS("8.1 Gbps link rate without sink TPS4 support\n");
}
/*
* Intel platforms that support HBR2 also support TPS3. TPS3 support is
* also mandatory for downstream devices that support HBR2. However, not
* all sinks follow the spec.
*/
source_tps3 = intel_dp_source_supports_hbr2(intel_dp);
sink_tps3 = drm_dp_tps3_supported(intel_dp->dpcd);
if (source_tps3 && sink_tps3) {
return DP_TRAINING_PATTERN_3;
} else if (intel_dp->link_rate >= 540000) {
if (!source_tps3)
DRM_DEBUG_KMS(">=5.4/6.48 Gbps link rate without source HBR2/TPS3 support\n");
if (!sink_tps3)
DRM_DEBUG_KMS(">=5.4/6.48 Gbps link rate without sink TPS3 support\n");
}
return DP_TRAINING_PATTERN_2;
}
static bool
intel_dp_link_training_channel_equalization(struct intel_dp *intel_dp)
{
int tries;
u32 training_pattern;
u8 link_status[DP_LINK_STATUS_SIZE];
bool channel_eq = false;
training_pattern = intel_dp_training_pattern(intel_dp);
/* Scrambling is disabled for TPS2/3 and enabled for TPS4 */
if (training_pattern != DP_TRAINING_PATTERN_4)
training_pattern |= DP_LINK_SCRAMBLING_DISABLE;
/* channel equalization */
if (!intel_dp_set_link_train(intel_dp,
training_pattern)) {
DRM_ERROR("failed to start channel equalization\n");
return false;
}
for (tries = 0; tries < 5; tries++) {
drm_dp_link_train_channel_eq_delay(intel_dp->dpcd);
if (!intel_dp_get_link_status(intel_dp, link_status)) {
DRM_ERROR("failed to get link status\n");
break;
}
/* Make sure clock is still ok */
if (!drm_dp_clock_recovery_ok(link_status,
intel_dp->lane_count)) {
intel_dp_dump_link_status(link_status);
DRM_DEBUG_KMS("Clock recovery check failed, cannot "
"continue channel equalization\n");
break;
}
if (drm_dp_channel_eq_ok(link_status,
intel_dp->lane_count)) {
channel_eq = true;
DRM_DEBUG_KMS("Channel EQ done. DP Training "
"successful\n");
break;
}
/* Update training set as requested by target */
intel_get_adjust_train(intel_dp, link_status);
if (!intel_dp_update_link_train(intel_dp)) {
DRM_ERROR("failed to update link training\n");
break;
}
}
/* Try 5 times, else fail and try at lower BW */
if (tries == 5) {
intel_dp_dump_link_status(link_status);
DRM_DEBUG_KMS("Channel equalization failed 5 times\n");
}
intel_dp_set_idle_link_train(intel_dp);
return channel_eq;
}
void intel_dp_stop_link_train(struct intel_dp *intel_dp)
{
intel_dp->link_trained = true;
intel_dp_set_link_train(intel_dp,
DP_TRAINING_PATTERN_DISABLE);
}
void
intel_dp_start_link_train(struct intel_dp *intel_dp)
{
struct intel_connector *intel_connector = intel_dp->attached_connector;
if (!intel_dp_link_training_clock_recovery(intel_dp))
goto failure_handling;
if (!intel_dp_link_training_channel_equalization(intel_dp))
goto failure_handling;
DRM_DEBUG_KMS("[CONNECTOR:%d:%s] Link Training Passed at Link Rate = %d, Lane count = %d",
intel_connector->base.base.id,
intel_connector->base.name,
intel_dp->link_rate, intel_dp->lane_count);
return;
failure_handling:
DRM_DEBUG_KMS("[CONNECTOR:%d:%s] Link Training failed at link rate = %d, lane count = %d",
intel_connector->base.base.id,
intel_connector->base.name,
intel_dp->link_rate, intel_dp->lane_count);
if (!intel_dp_get_link_train_fallback_values(intel_dp,
intel_dp->link_rate,
intel_dp->lane_count))
/* Schedule a Hotplug Uevent to userspace to start modeset */
schedule_work(&intel_connector->modeset_retry_work);
return;
}
