4.18-stable review patch. If anyone has any objections, please let me know.
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From: Manasi Navare manasi.d.navare@intel.com
commit 041444458835d7fb2c9f042598bfe16bf375b15d upstream.
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.
v3: * Add const for fixed_mode (Ville) v2: * Send uevent if link failure on eDP unconditionally
Fixes: c0cfb10d9e1d ("drm/i915/edp: Do not do link training fallback or prune modes on EDP") Cc: Clinton Taylor clinton.a.taylor@intel.com Cc: Jani Nikula jani.nikula@linux.intel.com Cc: Ville Syrjala ville.syrjala@linux.intel.com Cc: Daniel Vetter daniel.vetter@ffwll.ch Cc: Lucas De Marchi lucas.demarchi@intel.com Cc: stable@vger.kernel.org # v4.17+ Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=107489 Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=105338 Signed-off-by: Manasi Navare manasi.d.navare@intel.com Tested-by: Alexander Wilson alexander.wilson@ncf.edu Reviewed-by: Ville Syrjälä ville.syrjala@linux.intel.com Link: https://patchwork.freedesktop.org/patch/msgid/20181009212804.702-1-manasi.d.... (cherry picked from commit 1e712535c51ab025ebc776d4405683d81521996d) Signed-off-by: Rodrigo Vivi rodrigo.vivi@intel.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- drivers/gpu/drm/i915/intel_dp.c | 30 ++++++++++++++++++++++++++ drivers/gpu/drm/i915/intel_dp_link_training.c | 26 +++++++--------------- 2 files changed, 39 insertions(+), 17 deletions(-)
--- a/drivers/gpu/drm/i915/intel_dp.c +++ b/drivers/gpu/drm/i915/intel_dp.c @@ -387,6 +387,22 @@ static bool intel_dp_link_params_valid(s return true; }
+static bool intel_dp_can_link_train_fallback_for_edp(struct intel_dp *intel_dp, + int link_rate, + uint8_t lane_count) +{ + const 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) { @@ -396,9 +412,23 @@ int intel_dp_get_link_train_fallback_val 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 { --- a/drivers/gpu/drm/i915/intel_dp_link_training.c +++ b/drivers/gpu/drm/i915/intel_dp_link_training.c @@ -335,22 +335,14 @@ intel_dp_start_link_train(struct intel_d 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; }