[PATCH] drm/i915/hdcp: Disable the QSES check for HDCP 1.4 over MST

[Sean Paul]

From: Sean Paul <seanpaul at chromium.org>

The HDCP 1.4 spec does not require the QUERY_STREAM_ENCRYPTION_STATUS
check, it was always a nice-to-have. After deploying this across various
devices, we've determined that some MST bridge chips do not properly
support this call for HDCP 1.4 (namely Synaptics and Realtek).

I had considered creating a quirk for this, but I think it's more
prudent to just disable the check entirely since I don't have an idea
how widespread support is.

Signed-off-by: Sean Paul <seanpaul at chromium.org>
---
 drivers/gpu/drm/i915/display/intel_dp_hdcp.c | 26 +-------------------
 1 file changed, 1 insertion(+), 25 deletions(-)

diff --git a/drivers/gpu/drm/i915/display/intel_dp_hdcp.c b/drivers/gpu/drm/i915/display/intel_dp_hdcp.c
index 03424d20e9f7..b6a9606bf09a 100644
--- a/drivers/gpu/drm/i915/display/intel_dp_hdcp.c
+++ b/drivers/gpu/drm/i915/display/intel_dp_hdcp.c
@@ -640,30 +640,6 @@ intel_dp_mst_hdcp_toggle_signalling(struct intel_digital_port *dig_port,
 	return ret;
 }
 
-static
-bool intel_dp_mst_hdcp_check_link(struct intel_digital_port *dig_port,
-				  struct intel_connector *connector)
-{
-	struct drm_i915_private *i915 = to_i915(dig_port->base.base.dev);
-	struct intel_dp *intel_dp = &dig_port->dp;
-	struct drm_dp_query_stream_enc_status_ack_reply reply;
-	int ret;
-
-	if (!intel_dp_hdcp_check_link(dig_port, connector))
-		return false;
-
-	ret = drm_dp_send_query_stream_enc_status(&intel_dp->mst_mgr,
-						  connector->port, &reply);
-	if (ret) {
-		drm_dbg_kms(&i915->drm,
-			    "[CONNECTOR:%d:%s] failed QSES ret=%d\n",
-			    connector->base.base.id, connector->base.name, ret);
-		return false;
-	}
-
-	return reply.auth_completed && reply.encryption_enabled;
-}
-
 static const struct intel_hdcp_shim intel_dp_mst_hdcp_shim = {
 	.write_an_aksv = intel_dp_hdcp_write_an_aksv,
 	.read_bksv = intel_dp_hdcp_read_bksv,
@@ -674,7 +650,7 @@ static const struct intel_hdcp_shim intel_dp_mst_hdcp_shim = {
 	.read_ksv_fifo = intel_dp_hdcp_read_ksv_fifo,
 	.read_v_prime_part = intel_dp_hdcp_read_v_prime_part,
 	.toggle_signalling = intel_dp_mst_hdcp_toggle_signalling,
-	.check_link = intel_dp_mst_hdcp_check_link,
+	.check_link = intel_dp_hdcp_check_link,
 	.hdcp_capable = intel_dp_hdcp_capable,
 
 	.protocol = HDCP_PROTOCOL_DP,
-- 
Sean Paul, Software Engineer, Google / Chromium OS