[Intel-gfx] [PATCH v6 3/3] drm/i915: DP channel EQ check for use of DP link training optimization

[Mika Kahola]

Don't use DP link training optimization if channel EQ is not ok. It has
been reported that in case of failure in channel EQ check the link training
optimization can be enabled and therefore may not be able to reuse the
previously computed drive current and pre-emphasis levels.

v2: Added MST case (Ville)

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=91393
Signed-off-by: Mika Kahola <mika.kahola at intel.com>
---
 drivers/gpu/drm/i915/intel_dp.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
index 3137187..c995dbd 100644
--- a/drivers/gpu/drm/i915/intel_dp.c
+++ b/drivers/gpu/drm/i915/intel_dp.c
@@ -4254,6 +4254,7 @@ go_again:
 			if (intel_dp->active_mst_links &&
 			    !drm_dp_channel_eq_ok(&esi[10], intel_dp->lane_count)) {
 				DRM_DEBUG_KMS("channel EQ not ok, retraining\n");
+				intel_dp->train_set_valid = false;
 				intel_dp_start_link_train(intel_dp);
 				intel_dp_stop_link_train(intel_dp);
 			}
@@ -4354,6 +4355,7 @@ intel_dp_check_link_status(struct intel_dp *intel_dp)
 		(!drm_dp_channel_eq_ok(link_status, intel_dp->lane_count))) {
 		DRM_DEBUG_KMS("%s: channel EQ not ok, retraining\n",
 			      intel_encoder->base.name);
+		intel_dp->train_set_valid = false;
 		intel_dp_start_link_train(intel_dp);
 		intel_dp_stop_link_train(intel_dp);
 	}
-- 
1.9.1