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.
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>
Signed-off-by: Manasi Navare <manasi.d.navare@xxxxxxxxx>
---
drivers/gpu/drm/i915/intel_dp.c | 25 +++++++++++++++++++++++++
drivers/gpu/drm/i915/intel_dp_link_training.c | 26 +++++++++-----------------
2 files changed, 34 insertions(+), 17 deletions(-)
diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
index 2cc58596..7f7202a 100644
--- a/drivers/gpu/drm/i915/intel_dp.c
+++ b/drivers/gpu/drm/i915/intel_dp.c
@@ -387,6 +387,21 @@ 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)
{
@@ -396,9 +411,19 @@ 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))
+ return -1;
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))
+ return -1;
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 3fcaa98..6673975 100644
--- 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_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;
}
--
2.7.4
_______________________________________________
Intel-gfx mailing list
Intel-gfx@xxxxxxxxxxxxxxxxxxxxx
https://lists.freedesktop.org/mailman/listinfo/intel-gfx
