From d84c4d194ebad0f5d327da72404c37c7de2c1714 Mon Sep 17 00:00:00 2001 From: Jimmy Kizito Date: Thu, 14 Apr 2022 09:49:37 -0400 Subject: drm/amd/display: Update link training fallback behaviour. [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 Acked-by: Qingqing Zhuo Signed-off-by: Jimmy Kizito Tested-by: Daniel Wheeler Signed-off-by: Alex Deucher --- drivers/gpu/drm/amd/display/dc/core/dc_link_dp.c | 77 ++++++++++++++++-------- 1 file changed, 53 insertions(+), 24 deletions(-) (limited to 'drivers/gpu/drm/amd/display') 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; } -- cgit v1.2.3