[Intel-gfx] [PATCH 1/7] drm/i915: Fix DP link training pattern mask

[Imre Deak]

An LTTPR can be trained with training pattern 4 even if the DPCD
revision is < 1.4, but drm_dp_training_pattern_mask() would change
pattern 4 to pattern 3 on those DPCD revisions.

Since intel_dp_training_pattern() makes already sure that the proper
training pattern is used, all that needs to be masked out is the
scrambling disable flag, which is or'd to the mask later based on the
training pattern.

Signed-off-by: Imre Deak <imre.deak at intel.com>
---
 drivers/gpu/drm/i915/display/intel_ddi.c              |  3 +--
 drivers/gpu/drm/i915/display/intel_dp.c               | 10 +++++-----
 drivers/gpu/drm/i915/display/intel_dp_link_training.c |  2 +-
 3 files changed, 7 insertions(+), 8 deletions(-)

diff --git a/drivers/gpu/drm/i915/display/intel_ddi.c b/drivers/gpu/drm/i915/display/intel_ddi.c
index 4d06178cd76c..946a3b6f2d10 100644
--- a/drivers/gpu/drm/i915/display/intel_ddi.c
+++ b/drivers/gpu/drm/i915/display/intel_ddi.c
@@ -4158,13 +4158,12 @@ static void intel_ddi_set_link_train(struct intel_dp *intel_dp,
 				     u8 dp_train_pat)
 {
 	struct drm_i915_private *dev_priv = dp_to_i915(intel_dp);
-	u8 train_pat_mask = drm_dp_training_pattern_mask(intel_dp->dpcd);
 	u32 temp;
 
 	temp = intel_de_read(dev_priv, intel_dp->regs.dp_tp_ctl);
 
 	temp &= ~DP_TP_CTL_LINK_TRAIN_MASK;
-	switch (dp_train_pat & train_pat_mask) {
+	switch (dp_train_pat & ~DP_LINK_SCRAMBLING_DISABLE) {
 	case DP_TRAINING_PATTERN_DISABLE:
 		temp |= DP_TP_CTL_LINK_TRAIN_NORMAL;
 		break;
diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c
index bf1e9cf1c0f3..2a4a9c0e7427 100644
--- a/drivers/gpu/drm/i915/display/intel_dp.c
+++ b/drivers/gpu/drm/i915/display/intel_dp.c
@@ -3778,7 +3778,7 @@ cpt_set_link_train(struct intel_dp *intel_dp,
 
 	*DP &= ~DP_LINK_TRAIN_MASK_CPT;
 
-	switch (dp_train_pat & DP_TRAINING_PATTERN_MASK) {
+	switch (dp_train_pat & ~DP_LINK_SCRAMBLING_DISABLE) {
 	case DP_TRAINING_PATTERN_DISABLE:
 		*DP |= DP_LINK_TRAIN_OFF_CPT;
 		break;
@@ -3808,7 +3808,7 @@ g4x_set_link_train(struct intel_dp *intel_dp,
 
 	*DP &= ~DP_LINK_TRAIN_MASK;
 
-	switch (dp_train_pat & DP_TRAINING_PATTERN_MASK) {
+	switch (dp_train_pat & ~DP_LINK_SCRAMBLING_DISABLE) {
 	case DP_TRAINING_PATTERN_DISABLE:
 		*DP |= DP_LINK_TRAIN_OFF;
 		break;
@@ -4498,12 +4498,12 @@ intel_dp_program_link_training_pattern(struct intel_dp *intel_dp,
 				       u8 dp_train_pat)
 {
 	struct drm_i915_private *dev_priv = dp_to_i915(intel_dp);
-	u8 train_pat_mask = drm_dp_training_pattern_mask(intel_dp->dpcd);
 
-	if (dp_train_pat & train_pat_mask)
+	if ((dp_train_pat & ~DP_LINK_SCRAMBLING_DISABLE) !=
+	    DP_TRAINING_PATTERN_DISABLE)
 		drm_dbg_kms(&dev_priv->drm,
 			    "Using DP training pattern TPS%d\n",
-			    dp_train_pat & train_pat_mask);
+			    dp_train_pat & ~DP_LINK_SCRAMBLING_DISABLE);
 
 	intel_dp->set_link_train(intel_dp, dp_train_pat);
 }
diff --git a/drivers/gpu/drm/i915/display/intel_dp_link_training.c b/drivers/gpu/drm/i915/display/intel_dp_link_training.c
index f2c8b56be9ea..f8b53c5b5777 100644
--- a/drivers/gpu/drm/i915/display/intel_dp_link_training.c
+++ b/drivers/gpu/drm/i915/display/intel_dp_link_training.c
@@ -96,7 +96,7 @@ intel_dp_set_link_train(struct intel_dp *intel_dp,
 	intel_dp_program_link_training_pattern(intel_dp, dp_train_pat);
 
 	buf[0] = dp_train_pat;
-	if ((dp_train_pat & DP_TRAINING_PATTERN_MASK) ==
+	if ((dp_train_pat & ~DP_LINK_SCRAMBLING_DISABLE) ==
 	    DP_TRAINING_PATTERN_DISABLE) {
 		/* don't write DP_TRAINING_LANEx_SET on disable */
 		len = 1;
-- 
2.17.1