drm/i915/dp: Link train Fallback on eDP only if fallback link BW can fit panel's...

[linux.git] / drivers / gpu / drm / i915 / intel_dp.c

diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
index 0855b9785f7b23ce4b3700b3c8350ad0d900b97e..13ff89be6ad6a2626eaf6392a476296e06d4f406 100644 (file)
--- a/drivers/gpu/drm/i915/intel_dp.c
+++ b/drivers/gpu/drm/i915/intel_dp.c
@@ -557,6 +557,22 @@ 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)
+{
+       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)
 {
@@ -566,9 +582,23 @@ 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;
        } else {