drm/i915/dp: update training set in a burst write with training pattern set

The DP spec allows this, and requires it when full link training is
started with non-minimum voltage swing and/or non-zero pre-emphasis.

Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
index 3770147..bee09e1 100644 (file)
--- a/drivers/gpu/drm/i915/intel_dp.c
+++ b/drivers/gpu/drm/i915/intel_dp.c
@@ -2297,7 +2297,8 @@ intel_dp_set_link_train(struct intel_dp *intel_dp,
        struct drm_device *dev = intel_dig_port->base.base.dev;
        struct drm_i915_private *dev_priv = dev->dev_private;
        enum port port = intel_dig_port->port;
-       int ret;
+       uint8_t buf[sizeof(intel_dp->train_set) + 1];
+       int ret, len;
 
        if (HAS_DDI(dev)) {
                uint32_t temp = I915_READ(DP_TP_CTL(port));
@@ -2367,22 +2368,21 @@ intel_dp_set_link_train(struct intel_dp *intel_dp,
        I915_WRITE(intel_dp->output_reg, *DP);
        POSTING_READ(intel_dp->output_reg);
 
-       ret = intel_dp_aux_native_write_1(intel_dp, DP_TRAINING_PATTERN_SET,
-                                         dp_train_pat);
-       if (ret != 1)
-               return false;
-
-       if ((dp_train_pat & DP_TRAINING_PATTERN_MASK) !=
+       buf[0] = dp_train_pat;
+       if ((dp_train_pat & DP_TRAINING_PATTERN_MASK) ==
            DP_TRAINING_PATTERN_DISABLE) {
-               ret = intel_dp_aux_native_write(intel_dp,
-                                               DP_TRAINING_LANE0_SET,
-                                               intel_dp->train_set,
-                                               intel_dp->lane_count);
-               if (ret != intel_dp->lane_count)
-                       return false;
+               /* don't write DP_TRAINING_LANEx_SET on disable */
+               len = 1;
+       } else {
+               /* DP_TRAINING_LANEx_SET follow DP_TRAINING_PATTERN_SET */
+               memcpy(buf + 1, intel_dp->train_set, intel_dp->lane_count);
+               len = intel_dp->lane_count + 1;
        }
 
-       return true;
+       ret = intel_dp_aux_native_write(intel_dp, DP_TRAINING_PATTERN_SET,
+                                       buf, len);
+
+       return ret == len;
 }
 
 static bool