drm/i915: debug log for REPLY_ACK missing

Adding a debug log when the DP_AUX_NATIVE_REPLY_ACK is missing
for aksv write. This helps to locate the possible non responding
DP HDCP sinks.

v2:
  Rewritten for readability [Sean Paul]

Signed-off-by: Ramalingam C <ramalingam.c@intel.com>
Reviewed-by: Sean Paul <sean@poorly.run>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/1544010283-20223-4-git-send-email-ramalingam.c@intel.com

diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
index de4219721cbc2c16374b5838c0e71d43b3b41330..e94faa0a42eb39dae29344c6a061cf08a3558874 100644 (file)
--- a/drivers/gpu/drm/i915/intel_dp.c
+++ b/drivers/gpu/drm/i915/intel_dp.c
@@ -5616,7 +5616,12 @@ int intel_dp_hdcp_write_an_aksv(struct intel_digital_port *intel_dig_port,
        }
 
        reply = (rxbuf[0] >> 4) & DP_AUX_NATIVE_REPLY_MASK;
-       return reply == DP_AUX_NATIVE_REPLY_ACK ? 0 : -EIO;
+       if (reply != DP_AUX_NATIVE_REPLY_ACK) {
+               DRM_DEBUG_KMS("Aksv write: no DP_AUX_NATIVE_REPLY_ACK %x\n",
+                             reply);
+               return -EIO;
+       }
+       return 0;
 }
 
 static int intel_dp_hdcp_read_bksv(struct intel_digital_port *intel_dig_port,