If link training fails, then we need to fallback to lower
link rate first and if link training fails at RBR, then
fallback to lower lane count.
Signed-off-by: Manasi Navare <manasi.d.navare@xxxxxxxxx>
---
drivers/gpu/drm/i915/intel_dp.c | 28 ++++++++++++++++++++++++++++
drivers/gpu/drm/i915/intel_drv.h | 6 ++++++
2 files changed, 34 insertions(+)
diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
index 39116c8..369b5ce 100644
--- a/drivers/gpu/drm/i915/intel_dp.c
+++ b/drivers/gpu/drm/i915/intel_dp.c
@@ -303,6 +303,34 @@ static int intel_dp_link_rate_index(struct intel_dp *intel_dp,
return -1;
}
+void intel_dp_get_link_train_fallback_values(struct intel_dp *intel_dp,
+ int link_rate, uint8_t lane_count)
+{
+ int common_rates[DP_MAX_SUPPORTED_RATES] = {};
+ int common_len;
+ int link_rate_index = -1;
+
+ if (!intel_dp->link_train_failed)
+ return;
+
+ common_len = intel_dp_common_rates(intel_dp, common_rates);
+ link_rate_index = intel_dp_link_rate_index(intel_dp,
+ common_rates,
+ link_rate);
+ if (link_rate_index > 0) {
+ intel_dp->fallback_link_rate_index = link_rate_index - 1;
+ intel_dp->fallback_link_rate = common_rates[intel_dp->fallback_link_rate_index];
+ intel_dp->fallback_lane_count = intel_dp_max_lane_count(intel_dp);
+ } else if (lane_count > 1) {
+ intel_dp->fallback_link_rate_index = common_len -1;
+ intel_dp->fallback_link_rate = common_rates[intel_dp->fallback_link_rate_index];
+ intel_dp->fallback_lane_count = lane_count - 1;
+ } else {
+ DRM_ERROR ("Link Training Unsuccessful\n");
+ intel_dp->link_train_failed = false;
+ }
+}
+
static enum drm_mode_status
intel_dp_mode_valid(struct drm_connector *connector,
struct drm_display_mode *mode)
diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
index f6fe05a..c6789ee 100644
--- a/drivers/gpu/drm/i915/intel_drv.h
+++ b/drivers/gpu/drm/i915/intel_drv.h
@@ -890,6 +890,10 @@ struct intel_dp {
uint32_t DP;
int link_rate;
uint8_t lane_count;
+ int fallback_link_rate;
+ uint8_t fallback_lane_count;
+ int fallback_link_rate_index;
+ bool link_train_failed;
uint8_t sink_count;
bool link_mst;
bool has_audio;
@@ -1402,6 +1406,8 @@ int intel_dp_set_link_status_property(struct drm_connector *connector,
void intel_dp_set_link_params(struct intel_dp *intel_dp,
int link_rate, uint8_t lane_count,
bool link_mst);
+void intel_dp_get_link_train_fallback_values(struct intel_dp *intel_dp,
+ int link_rate, uint8_t lane_count);
void intel_dp_start_link_train(struct intel_dp *intel_dp);
void intel_dp_stop_link_train(struct intel_dp *intel_dp);
void intel_dp_sink_dpms(struct intel_dp *intel_dp, int mode);
--
1.9.1
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