[PATCH] drm/i915/dp: On DPCD read failure skip LT

[Arun R Murthy <arun.r.murthy@intel.com>]

The commit e42e7e585984 ("drm/i915: Fix modesetting in case of
unexpected AUX timeouts") continue the LT even if DPCD read failed.

But doing so will blot the dmesg with multiple AUX Tx errors, so skip
the LT but continue the modeset seq for the reason said in the above
mentioned patch.

Signed-off-by: Arun R Murthy <arun.r.murthy@intel.com>
---
 drivers/gpu/drm/i915/display/intel_dp_link_training.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

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 a26094223f78..2598e4ba9712 100644
--- a/drivers/gpu/drm/i915/display/intel_dp_link_training.c
+++ b/drivers/gpu/drm/i915/display/intel_dp_link_training.c
@@ -1776,9 +1776,12 @@ void intel_dp_start_link_train(struct intel_atomic_state *state,
 
 	lttpr_count = intel_dp_init_lttpr_and_dprx_caps(intel_dp);
 
-	if (lttpr_count < 0)
-		/* Still continue with enabling the port and link training. */
-		lttpr_count = 0;
+	if (lttpr_count < 0) {
+		/* skip LT but complete the modeset seq */
+		lt_dbg(intel_dp, DP_PHY_DPRX,
+		       "Reading LTTPR/DPRX caps failed, skip LT\n");
+		goto retry;
+	}
 
 	intel_dp_prepare_link_train(intel_dp, crtc_state);
 
@@ -1795,6 +1798,7 @@ void intel_dp_start_link_train(struct intel_atomic_state *state,
 		return;
 	}
 
+retry:
 	intel_dp->link.seq_train_failures++;
 
 	/*
-- 
2.25.1