[PATCH v4] drm/i915: dont retry stream management at seq_num_m roll over

[Ramalingam C]

When roll over detected for seq_num_m, we shouldn't continue with stream
management with rolled over value.

So we are terminating the stream management retry, on roll over of the
seq_num_m.

v2:
  using drm_dbg_kms instead of DRM_DEBUG_KMS [Anshuman]
v3:
  dev_priv is used as i915 [JaniN]
v4:
  roll over of seq_num_m detected at the start of stream management.

Signed-off-by: Ramalingam C <ramalingam.c at intel.com>
---
 drivers/gpu/drm/i915/display/intel_hdcp.c | 17 +++++++++++------
 1 file changed, 11 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/i915/display/intel_hdcp.c b/drivers/gpu/drm/i915/display/intel_hdcp.c
index b24d12efae0a..f4b1dd1e62e7 100644
--- a/drivers/gpu/drm/i915/display/intel_hdcp.c
+++ b/drivers/gpu/drm/i915/display/intel_hdcp.c
@@ -1391,6 +1391,13 @@ int _hdcp2_propagate_stream_management_info(struct intel_connector *connector)
 	const struct intel_hdcp_shim *shim = hdcp->shim;
 	int ret;
 
+	/*
+	 * seq_num_m roll over is possible only when dynamic update of
+	 * content type is supported. But implementing as per the spec.
+	 */
+	if (hdcp->seq_num_m > HDCP_2_2_SEQ_NUM_MAX)
+		return -1;
+
 	/* Prepare RepeaterAuth_Stream_Manage msg */
 	msgs.stream_manage.msg_id = HDCP_2_2_REP_STREAM_MANAGE;
 	drm_hdcp_cpu_to_be24(msgs.stream_manage.seq_num_m, hdcp->seq_num_m);
@@ -1419,11 +1426,6 @@ int _hdcp2_propagate_stream_management_info(struct intel_connector *connector)
 
 err_exit:
 	hdcp->seq_num_m++;
-	if (hdcp->seq_num_m > HDCP_2_2_SEQ_NUM_MAX) {
-		DRM_DEBUG_KMS("seq_num_m roll over.\n");
-		ret = -1;
-	}
-
 	return ret;
 }
 
@@ -1618,8 +1620,11 @@ hdcp2_propagate_stream_management_info(struct intel_connector *connector)
 
 	for (i = 0; i < tries; i++) {
 		ret = _hdcp2_propagate_stream_management_info(connector);
-		if (!ret)
+		if (!ret || connector->hdcp.seq_num_m > HDCP_2_2_SEQ_NUM_MAX) {
+			if (connector->hdcp.seq_num_m > HDCP_2_2_SEQ_NUM_MAX)
+				drm_dbg_kms(&i915->drm, "seq_num_m roll over.\n");
 			break;
+		}
 
 		drm_dbg_kms(&i915->drm,
 			    "HDCP2 stream management %d of %d Failed.(%d)\n",
-- 
2.20.1