On Wed, Sep 12, 2018 at 03:57:16PM -0700, Manasi Navare wrote: > 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 <clinton.a.tay...@intel.com> > Cc: Jani Nikula <jani.nik...@linux.intel.com> > Cc: Ville Syrjala <ville.syrj...@linux.intel.com> > Cc: Daniel Vetter <daniel.vet...@ffwll.ch> > Cc: Lucas De Marchi <lucas.demar...@intel.com> > 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.nav...@intel.com> > Tested-by: Alexander Wilson <alexander.wil...@ncf.edu> > --- > 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 436c22de33b6..e4de5257cd87 100644 > --- a/drivers/gpu/drm/i915/intel_dp.c > +++ b/drivers/gpu/drm/i915/intel_dp.c > @@ -557,6 +557,21 @@ 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;
const > + 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; I wonder if we should extract this into a helper and share with mode_valid(). Then again, it's just a few lines so maybe not worth it. > + > + return true; > +} > + > int intel_dp_get_link_train_fallback_values(struct intel_dp *intel_dp, > int link_rate, uint8_t lane_count) > { > @@ -566,9 +581,23 @@ 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; This whole thing is getting a bit messy. I think it would worthwile to rewrite this as something like: intel_dp_update_link_train_fallback_values(intel_dp) { int link_rate = intel_dp->link_rate; int lane_count = intel_dp->lane_count; if (intel_dp_get_link_train_fallback_values(intel_dp, &link_rate, &lane_count)) return -1; if (is_edp() && !edp_can_link_train_thing(link_rate, lane_count)) { DRM_DEBUG_KMS("..."); return 0; } intel_dp->max_link_rate = link_rate; intel_dp->max_link_lane_count = lane_count; return 0; } But that can be done later. With the missing const added this patch is Reviewed-by: Ville Syrjälä <ville.syrj...@linux.intel.com> > } 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 -- Ville Syrjälä Intel _______________________________________________ Intel-gfx mailing list Intel-gfx@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/intel-gfx