From 88a37d925ba6754b06b6ddeb9de2fca79693ca3b Mon Sep 17 00:00:00 2001 From: Manasi Navare Date: Wed, 16 May 2018 18:37:15 -0700 Subject: [PATCH v2] drm/i915/dp: Link train Fallback on eDP only if fallback link BW can fit panel's native mode This patch fixes the original commit c0cfb10d9e1de49 ("drm/i915/edp: Do not do link training fallback or prune modes on EDP") that causes a blank screen in case of certain eDP panels (Eg: seen on Dell XPS13 9350) where first link training fails and a retraining is required by falling back to lower link rate/lane count. In case of some panels they advertise higher link rate/lane count than whats required for supporting the panel's native mode. But we always link train at highest link rate/lane count for eDP and if that fails we can still fallback to lower link rate/lane count as long as the fallback link BW still fits the native mode to avoid pruning the panel's native mode yet retraining at fallback values to recover from a blank screen. v2: * Send uevent if link failure on eDP unconditionally Cc: Clinton Taylor Cc: Jani Nikula Cc: Ville Syrjala Cc: Daniel Vetter Cc: Lucas De Marchi Signed-off-by: Manasi Navare --- drivers/gpu/drm/i915/intel_dp.c | 29 +++++++++++++++++++ drivers/gpu/drm/i915/intel_dp_link_training.c | 26 ++++++----------- 2 files changed, 38 insertions(+), 17 deletions(-) diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c index 8e0e14ba534f..ae4903771978 100644 --- a/drivers/gpu/drm/i915/intel_dp.c +++ b/drivers/gpu/drm/i915/intel_dp.c @@ -564,6 +564,21 @@ static bool intel_dp_link_params_valid(struct intel_dp *intel_dp, int link_rate, return true; } +static bool intel_dp_can_link_train_fallback_for_edp(struct intel_dp *intel_dp, + int link_rate, + uint8_t lane_count) +{ + struct drm_display_mode *fixed_mode = intel_dp->attached_connector->panel.fixed_mode; + int mode_rate, max_rate; + + mode_rate = intel_dp_link_required(fixed_mode->clock, 18); + max_rate = intel_dp_max_data_rate(link_rate, lane_count); + if (mode_rate > max_rate) + return false; + + return true; +} + int intel_dp_get_link_train_fallback_values(struct intel_dp *intel_dp, int link_rate, uint8_t lane_count) { @@ -573,9 +588,23 @@ int intel_dp_get_link_train_fallback_values(struct intel_dp *intel_dp, intel_dp->num_common_rates, link_rate); if (index > 0) { + if (intel_dp_is_edp(intel_dp) && + !intel_dp_can_link_train_fallback_for_edp(intel_dp, + intel_dp->common_rates[index-1], + lane_count)) { + DRM_DEBUG_KMS("Retrying Link training for eDP with same parameters\n"); + return 0; + } intel_dp->max_link_rate = intel_dp->common_rates[index - 1]; intel_dp->max_link_lane_count = lane_count; } else if (lane_count > 1) { + if (intel_dp_is_edp(intel_dp) && + !intel_dp_can_link_train_fallback_for_edp(intel_dp, + intel_dp_max_common_rate(intel_dp), + lane_count >> 1)) { + DRM_DEBUG_KMS("Retrying Link training for eDP with same parameters\n"); + return 0; + } intel_dp->max_link_rate = intel_dp_max_common_rate(intel_dp); intel_dp->max_link_lane_count = lane_count >> 1; } else { diff --git a/drivers/gpu/drm/i915/intel_dp_link_training.c b/drivers/gpu/drm/i915/intel_dp_link_training.c index a9f40985a621..30be0e39bd5f 100644 --- a/drivers/gpu/drm/i915/intel_dp_link_training.c +++ b/drivers/gpu/drm/i915/intel_dp_link_training.c @@ -367,22 +367,14 @@ intel_dp_start_link_train(struct intel_dp *intel_dp) return; failure_handling: - /* Dont fallback and prune modes if its eDP */ - if (!intel_dp_is_edp(intel_dp)) { - 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); - } else { - DRM_ERROR("[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); - } + 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; } -- 2.18.0