On Mon, Oct 01, 2018 at 07:03:52PM +0300, Ville Syrjälä wrote: > 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.taylor@xxxxxxxxx> > > Cc: Jani Nikula <jani.nikula@xxxxxxxxxxxxxxx> > > Cc: Ville Syrjala <ville.syrjala@xxxxxxxxxxxxxxx> > > Cc: Daniel Vetter <daniel.vetter@xxxxxxxx> > > Cc: Lucas De Marchi <lucas.demarchi@xxxxxxxxx> > > 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@xxxxxxxxx> > > Tested-by: Alexander Wilson <alexander.wilson@xxxxxxx> > > --- > > 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 > Will add const to the 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; > > 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.syrjala@xxxxxxxxxxxxxxx> > Yes this can be refactored/reorganized as a follow up patch, also when downclock mode checks get in. So until then thsi fix is good to be merged right? Manasi > > } 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@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/intel-gfx