From: Jimmy Kizito <jimmy.kiz...@amd.com>
[Why]
Some displays may need several link training attempts before
link training succeeds.
[How]
If training succeeds after falling back to lower link bandwidth,
retry at original link bandwidth instead of abandoning link training
whenever link bandwidth is less than stream bandwidth.
Reviewed-by: Jun Lei <jun....@amd.com>
Acked-by: Qingqing Zhuo <qingqing.z...@amd.com>
Signed-off-by: Jimmy Kizito <jimmy.kiz...@amd.com>
---
.../gpu/drm/amd/display/dc/core/dc_link_dp.c | 77 +++++++++++++------
1 file changed, 53 insertions(+), 24 deletions(-)
diff --git a/drivers/gpu/drm/amd/display/dc/core/dc_link_dp.c
b/drivers/gpu/drm/amd/display/dc/core/dc_link_dp.c
index 975d631534b5..d8de8dbf3676 100644
--- a/drivers/gpu/drm/amd/display/dc/core/dc_link_dp.c
+++ b/drivers/gpu/drm/amd/display/dc/core/dc_link_dp.c
@@ -2783,31 +2783,37 @@ bool perform_link_training_with_retries(
struct dc_link *link = stream->link;
enum dp_panel_mode panel_mode = dp_get_panel_mode(link);
enum link_training_result status = LINK_TRAINING_CR_FAIL_LANE0;
- struct dc_link_settings current_setting = *link_setting;
+ struct dc_link_settings cur_link_settings = *link_setting;
const struct link_hwss *link_hwss = get_link_hwss(link,
&pipe_ctx->link_res);
int fail_count = 0;
+ bool is_link_bw_low = false; /* link bandwidth < stream bandwidth */
+ bool is_link_bw_min = /* RBR x 1 */
+ (cur_link_settings.link_rate <= LINK_RATE_LOW) &&
+ (cur_link_settings.lane_count <= LANE_COUNT_ONE);
dp_trace_commit_lt_init(link);
- if (dp_get_link_encoding_format(¤t_setting) == DP_8b_10b_ENCODING)
+ if (dp_get_link_encoding_format(&cur_link_settings) ==
DP_8b_10b_ENCODING)
/* We need to do this before the link training to ensure the
idle
* pattern in SST mode will be sent right after the link
training
*/
link_hwss->setup_stream_encoder(pipe_ctx);
dp_trace_set_lt_start_timestamp(link, false);
- for (j = 0; j < attempts; ++j) {
+ j = 0;
+ while (j < attempts && fail_count < (attempts * 10)) {
- DC_LOG_HW_LINK_TRAINING("%s: Beginning link training attempt %u
of %d\n",
- __func__, (unsigned int)j + 1, attempts);
+ DC_LOG_HW_LINK_TRAINING("%s: Beginning link training attempt %u
of %d @ rate(%d) x lane(%d)\n",
+ __func__, (unsigned int)j + 1, attempts,
cur_link_settings.link_rate,
+ cur_link_settings.lane_count);
dp_enable_link_phy(
link,
&pipe_ctx->link_res,
signal,
pipe_ctx->clock_source->id,
- ¤t_setting);
+ &cur_link_settings);
if (stream->sink_patches.dppowerup_delay > 0) {
int delay_dp_power_up_in_ms =
stream->sink_patches.dppowerup_delay;
@@ -2832,30 +2838,30 @@ bool perform_link_training_with_retries(
dp_set_panel_mode(link, panel_mode);
if (link->aux_access_disabled) {
- dc_link_dp_perform_link_training_skip_aux(link,
&pipe_ctx->link_res, ¤t_setting);
+ dc_link_dp_perform_link_training_skip_aux(link,
&pipe_ctx->link_res, &cur_link_settings);
return true;
} else {
/** @todo Consolidate USB4 DP and DPx.x training. */
if (link->ep_type == DISPLAY_ENDPOINT_USB4_DPIA) {
status =
dc_link_dpia_perform_link_training(link,
&pipe_ctx->link_res,
- ¤t_setting,
+ &cur_link_settings,
skip_video_pattern);
/* Transmit idle pattern once training
successful. */
- if (status == LINK_TRAINING_SUCCESS)
+ if (status == LINK_TRAINING_SUCCESS &&
!is_link_bw_low)
dp_set_hw_test_pattern(link,
&pipe_ctx->link_res, DP_TEST_PATTERN_VIDEO_MODE, NULL, 0);
} else {
status = dc_link_dp_perform_link_training(link,
&pipe_ctx->link_res,
- ¤t_setting,
+ &cur_link_settings,
skip_video_pattern);
}
dp_trace_lt_total_count_increment(link, false);
dp_trace_lt_result_update(link, status, false);
dp_trace_set_lt_end_timestamp(link, false);
- if (status == LINK_TRAINING_SUCCESS)
+ if (status == LINK_TRAINING_SUCCESS && !is_link_bw_low)
return true;
}
@@ -2866,8 +2872,9 @@ bool perform_link_training_with_retries(
if (j == (attempts - 1) && link->ep_type ==
DISPLAY_ENDPOINT_PHY)
break;
- DC_LOG_WARNING("%s: Link training attempt %u of %d failed\n",
- __func__, (unsigned int)j + 1, attempts);
+ DC_LOG_WARNING("%s: Link training attempt %u of %d failed @
rate(%d) x lane(%d)\n",
+ __func__, (unsigned int)j + 1, attempts,
cur_link_settings.link_rate,
+ cur_link_settings.lane_count);
dp_disable_link_phy(link, &pipe_ctx->link_res, signal);
@@ -2876,27 +2883,49 @@ bool perform_link_training_with_retries(
enum dc_connection_type type = dc_connection_none;
dc_link_detect_sink(link, &type);
- if (type == dc_connection_none)
+ if (type == dc_connection_none) {
+ DC_LOG_HW_LINK_TRAINING("%s: Aborting training
because sink unplugged\n", __func__);
break;
- } else if (do_fallback) {
+ }
+ }
+
+ /* Try to train again at original settings if:
+ * - not falling back between training attempts;
+ * - aborted previous attempt due to reasons other than sink
unplug;
+ * - successfully trained but at a link rate lower than that
required by stream;
+ * - reached minimum link bandwidth.
+ */
+ if (!do_fallback || (status == LINK_TRAINING_ABORT) ||
+ (status == LINK_TRAINING_SUCCESS &&
is_link_bw_low) ||
+ is_link_bw_min) {
+ j++;
+ cur_link_settings = *link_setting;
+ delay_between_attempts += LINK_TRAINING_RETRY_DELAY;
+ is_link_bw_low = false;
+ is_link_bw_min = (cur_link_settings.link_rate <=
LINK_RATE_LOW) &&
+ (cur_link_settings.lane_count <=
LANE_COUNT_ONE);
+
+ } else if (do_fallback) { /* Try training at lower link
bandwidth if doing fallback. */
uint32_t req_bw;
uint32_t link_bw;
- decide_fallback_link_setting(link, *link_setting,
¤t_setting, status);
- /* Fail link training if reduced link bandwidth no
longer meets
- * stream requirements.
+ decide_fallback_link_setting(link, *link_setting,
&cur_link_settings, status);
+ /* Flag if reduced link bandwidth no longer meets
stream requirements or fallen back to
+ * minimum link bandwidth.
*/
req_bw =
dc_bandwidth_in_kbps_from_timing(&stream->timing);
- link_bw = dc_link_bandwidth_kbps(link,
¤t_setting);
- if (req_bw > link_bw)
- break;
+ link_bw = dc_link_bandwidth_kbps(link,
&cur_link_settings);
+ is_link_bw_low = (req_bw > link_bw);
+ is_link_bw_min = ((cur_link_settings.link_rate <=
LINK_RATE_LOW) &&
+ (cur_link_settings.lane_count <=
LANE_COUNT_ONE));
+
+ if (is_link_bw_low)
+ DC_LOG_WARNING("%s: Link bandwidth too low
after fallback req_bw(%d) > link_bw(%d)\n",
+ __func__, req_bw, link_bw);
}
msleep(delay_between_attempts);
-
- delay_between_attempts += LINK_TRAINING_RETRY_DELAY;
}
-
return false;
}
--
2.25.1
