drm/i915/dp: Zero the DPCD data before connection probe

Signed-off-by: Adam Jackson <ajax@redhat.com>
Reviewed-by: Keith Packard <keithp@keithp.com>
Signed-off-by: Keith Packard <keithp@keithp.com>
diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
index e2aced6..de24f31 100644
--- a/drivers/gpu/drm/i915/intel_dp.c
+++ b/drivers/gpu/drm/i915/intel_dp.c
@@ -1673,6 +1673,7 @@
 	struct edid *edid = NULL;
 
 	intel_dp->has_audio = false;
+	memset(intel_dp->dpcd, 0, sizeof(intel_dp->dpcd));
 
 	if (HAS_PCH_SPLIT(dev))
 		status = ironlake_dp_detect(intel_dp);