From: Ramalingam C <ramalingam.c@intel.com>
Date: Sat, 3 Feb 2018 03:39:09 +0530
Subject: drm/i915: Reauthenticate HDCP on failure
Git-commit: 6d983946513b05102e1c41ea195ce7f7a65e7047
Patch-mainline: v4.17-rc1
References: FATE#326289 FATE#326079 FATE#326049 FATE#322398 FATE#326166

Incase of HDCP authentication failure, HDCP spec expects
reauthentication. Hence this patch adds the reauthentications
to be compliance with spec.

v2:
  do-while to for loop for simplicity. [Seanpaul]

v3:
  positioning the logs effectively. [Seanpaul]

Signed-off-by: Ramalingam C <ramalingam.c@intel.com>
Signed-off-by: Sean Paul <seanpaul@chromium.org>
Link: https://patchwork.freedesktop.org/patch/msgid/1517609350-10698-8-git-send-email-ramalingam.c@intel.com

Acked-by: Petr Tesarik <ptesarik@suse.com>
---
 drivers/gpu/drm/i915/intel_hdcp.c |   18 +++++++++++-------
 1 file changed, 11 insertions(+), 7 deletions(-)

--- a/drivers/gpu/drm/i915/intel_hdcp.c
+++ b/drivers/gpu/drm/i915/intel_hdcp.c
@@ -575,7 +575,7 @@ static int _intel_hdcp_disable(struct in
 static int _intel_hdcp_enable(struct intel_connector *connector)
 {
 	struct drm_i915_private *dev_priv = connector->base.dev->dev_private;
-	int i, ret;
+	int i, ret, tries = 3;
 
 	DRM_DEBUG_KMS("[%s:%d] HDCP is being enabled...\n",
 		      connector->base.name, connector->base.base.id);
@@ -596,17 +596,21 @@ static int _intel_hdcp_enable(struct int
 		return ret;
 	}
 
-	ret = intel_hdcp_auth(conn_to_dig_port(connector),
-			      connector->hdcp_shim);
-	if (ret) {
-		DRM_ERROR("Failed to authenticate HDCP (%d)\n", ret);
+	/* Incase of authentication failures, HDCP spec expects reauth. */
+	for (i = 0; i < tries; i++) {
+		ret = intel_hdcp_auth(conn_to_dig_port(connector),
+				      connector->hdcp_shim);
+		if (!ret)
+			return 0;
+
+		DRM_DEBUG_KMS("HDCP Auth failure (%d)\n", ret);
 
 		/* Ensuring HDCP encryption and signalling are stopped. */
 		_intel_hdcp_disable(connector);
-		return ret;
 	}
 
-	return 0;
+	DRM_ERROR("HDCP authentication failed (%d tries/%d)\n", tries, ret);
+	return ret;
 }
 
 static void intel_hdcp_check_work(struct work_struct *work)