[Intel-gfx] [PATCH v1] drm/i915: Minor link training logic fixes for dp_mst

Stanislav Lisovskiy stanislav.lisovskiy at intel.com
Wed May 27 20:00:22 UTC 2020

First of all *_needs_link_retraining function should return
false is link_train is set to true but not false.

Also if we detect channel eq problem when checking mst status
we simply bail out, without setting link_train to false again,
which might end up in a situation that we don't do link retraining
when needed.

There were some issues, when we had several problems with dp mst
and at the same time the log was floode by messages about
"channel eq not ok, need retraining" however the actual training
seems to be never done.

Signed-off-by: Stanislav Lisovskiy <stanislav.lisovskiy at intel.com>
 drivers/gpu/drm/i915/display/intel_dp.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c
index 1768731678a1..9288dc1f8914 100644
--- a/drivers/gpu/drm/i915/display/intel_dp.c
+++ b/drivers/gpu/drm/i915/display/intel_dp.c
@@ -5627,6 +5627,7 @@ intel_dp_check_mst_status(struct intel_dp *intel_dp)
 				    "channel EQ not ok, retraining\n");
 			need_retrain = true;
+			intel_dp->link_trained = false;
 		drm_dbg_kms(&i915->drm, "got esi %3ph\n", esi);
@@ -5654,7 +5655,7 @@ intel_dp_needs_link_retrain(struct intel_dp *intel_dp)
 	u8 link_status[DP_LINK_STATUS_SIZE];
-	if (!intel_dp->link_trained)
+	if (intel_dp->link_trained)
 		return false;

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