drm/i915: Initiate DP link training only on the lanes we'll be using

Limit the link training setting command to the lanes needed for the
current mode. It seems vaguely possible that a monitor will try to
train the other lanes and fail in some way, so this seems like the
safer plan.

Signed-off-by: Keith Packard <keithp@keithp.com>
Reviewed-by: Jesse Barnes <jbarnes@virtuousgeek.org>

1 files changed, 3 insertions, 2 deletions

diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
index 7bdf77e79798..8c3819b02a7f 100644
--- a/drivers/gpu/drm/i915/intel_dp.c
+++ b/drivers/gpu/drm/i915/intel_dp.c
@@ -1564,8 +1564,9 @@ intel_dp_set_link_train(struct intel_dp *intel_dp,
 
         ret = intel_dp_aux_native_write(intel_dp,
                                         DP_TRAINING_LANE0_SET,
-                                        intel_dp->train_set, 4);
-        if (ret != 4)
+                                        intel_dp->train_set,
+                                        intel_dp->lane_count);
+        if (ret != intel_dp->lane_count)
                 return false;
 
         return true;