4.15-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 a306343bcd7df89d9d45a601929e26866e7b7a81 upstream.
In case of eDP because the panel has a fixed mode, the link rate and lane count at which it is trained corresponds to the link BW required to support the native resolution of the panel. In case of panles with lower resolutions where fewer lanes are hooked up internally, that number is reflected in the MAX_LANE_COUNT DPCD register of the panel. So it is pointless to fallback to lower link rate/lane count in case of link training failure on eDP connector since the lower link BW will not support the native resolution of the panel and we cannot prune the preferred mode on the eDP connector.
In case of Link training failure on the eDP panel, something is wrong in the HW internally and hence driver errors out with a loud and clear DRM_ERROR message.
v2: * Fix the DEBUG_ERROR and add {} in else (Ville Syrjala)
Cc: Clinton Taylor clinton.a.taylor@intel.com Cc: Jim Bride jim.bride@linux.intel.com Cc: Jani Nikula jani.nikula@linux.intel.com Cc: Ville Syrjala ville.syrjala@linux.intel.com Cc: Dave Airlie airlied@redhat.com Cc: Daniel Vetter daniel.vetter@ffwll.ch Signed-off-by: Manasi Navare manasi.d.navare@intel.com Reviewed-by: Ville Syrjala ville.syrjala@linux.intel.com Reference: https://bugs.freedesktop.org/show_bug.cgi?id=103369 Signed-off-by: Imre Deak imre.deak@intel.com Link: https://patchwork.freedesktop.org/patch/msgid/1507835618-23051-1-git-send-em... (cherry picked from commit c0cfb10d9e1de490e36d3b9d4228c0ea0ca30677) Signed-off-by: Rodrigo Vivi rodrigo.vivi@intel.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- drivers/gpu/drm/i915/intel_dp_link_training.c | 26 +++++++++++++++++--------- 1 file changed, 17 insertions(+), 9 deletions(-)
--- a/drivers/gpu/drm/i915/intel_dp_link_training.c +++ b/drivers/gpu/drm/i915/intel_dp_link_training.c @@ -328,14 +328,22 @@ intel_dp_start_link_train(struct intel_d 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); + /* 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); + } return; }