drm/i915/hdcp: mst streams type1 capability check

It requires to check streams type1 capability in mst topology
by checking Rxinfo instead connector HDCP2.x capability in
order to enforce type0 stream encryption in a mix of
HDCP {1.x,2.x} mst topology.
Rxcaps always shows HDCP 2.x capability of immediate downstream
connector. Let's use Rxinfo HDCP1_DEVICE_DOWNSTREAM bit to
detect a HDCP {1.x,2.x} mix mst topology.

Cc: Sean Paul <seanpaul@chromium.org>
Cc: Ramalingam C <ramalingam.c@intel.com>
Signed-off-by: Anshuman Gupta <anshuman.gupta@intel.com>
Reviewed-by: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210319091732.17547-1-anshuman.gupta@intel.com

drivers/gpu/drm/i915/display/intel_display_types.h

@@ -387,6 +387,10 @@ struct intel_hdcp_shim {
 	int (*hdcp_2_2_capable)(struct intel_digital_port *dig_port,
 				bool *capable);
 
+	/* Detects whether a HDCP 1.4 sink connected in MST topology */
+	int (*streams_type1_capable)(struct intel_connector *connector,
+				     bool *capable);
+
 	/* Write HDCP2.2 messages */
 	int (*write_2_2_msg)(struct intel_digital_port *dig_port,
 			     void *buf, size_t size);

drivers/gpu/drm/i915/display/intel_dp_hdcp.c

@@ -478,6 +478,23 @@ int intel_dp_hdcp2_write_msg(struct intel_digital_port *dig_port,
 	return size;
 }
 
+static int
+get_rxinfo_hdcp_1_dev_downstream(struct intel_digital_port *dig_port, bool *hdcp_1_x)
+{
+	u8 rx_info[HDCP_2_2_RXINFO_LEN];
+	int ret;
+
+	ret = drm_dp_dpcd_read(&dig_port->dp.aux,
+			       DP_HDCP_2_2_REG_RXINFO_OFFSET,
+			       (void *)rx_info, HDCP_2_2_RXINFO_LEN);
+
+	if (ret != HDCP_2_2_RXINFO_LEN)
+		return ret >= 0 ? -EIO : ret;
+
+	*hdcp_1_x = HDCP_2_2_HDCP1_DEVICE_CONNECTED(rx_info[1]) ? true : false;
+	return 0;
+}
+
 static
 ssize_t get_receiver_id_list_size(struct intel_digital_port *dig_port)
 {
@@ -626,6 +643,27 @@ int intel_dp_hdcp2_capable(struct intel_digital_port *dig_port,
 	return 0;
 }
 
+static
+int intel_dp_mst_streams_type1_capable(struct intel_connector *connector,
+				       bool *capable)
+{
+	struct intel_digital_port *dig_port = intel_attached_dig_port(connector);
+	struct drm_i915_private *i915 = to_i915(dig_port->base.base.dev);
+	int ret;
+	bool hdcp_1_x;
+
+	ret = get_rxinfo_hdcp_1_dev_downstream(dig_port, &hdcp_1_x);
+	if (ret) {
+		drm_dbg_kms(&i915->drm,
+			    "[%s:%d] failed to read RxInfo ret=%d\n",
+			    connector->base.name, connector->base.base.id, ret);
+		return ret;
+	}
+
+	*capable = !hdcp_1_x;
+	return 0;
+}
+
 static const struct intel_hdcp_shim intel_dp_hdcp_shim = {
 	.write_an_aksv = intel_dp_hdcp_write_an_aksv,
 	.read_bksv = intel_dp_hdcp_read_bksv,
@@ -774,6 +812,7 @@ static const struct intel_hdcp_shim intel_dp_mst_hdcp_shim = {
 	.stream_2_2_encryption = intel_dp_mst_hdcp2_stream_encryption,
 	.check_2_2_link = intel_dp_mst_hdcp2_check_link,
 	.hdcp_2_2_capable = intel_dp_hdcp2_capable,
+	.streams_type1_capable = intel_dp_mst_streams_type1_capable,
 	.protocol = HDCP_PROTOCOL_DP,
 };
 

drivers/gpu/drm/i915/display/intel_hdcp.c

@@ -32,6 +32,21 @@ static int intel_conn_to_vcpi(struct intel_connector *connector)
 	return connector->port	? connector->port->vcpi.vcpi : 0;
 }
 
+static bool
+intel_streams_type1_capable(struct intel_connector *connector)
+{
+	const struct intel_hdcp_shim *shim = connector->hdcp.shim;
+	bool capable = false;
+
+	if (!shim)
+		return capable;
+
+	if (shim->streams_type1_capable)
+		shim->streams_type1_capable(connector, &capable);
+
+	return capable;
+}
+
 /*
  * intel_hdcp_required_content_stream selects the most highest common possible HDCP
  * content_type for all streams in DP MST topology because security f/w doesn't
@@ -70,7 +85,7 @@ intel_hdcp_required_content_stream(struct intel_digital_port *dig_port)
 		if (conn_dig_port != dig_port)
 			continue;
 
-		if (!enforce_type0 && !intel_hdcp2_capable(connector))
+		if (!enforce_type0 && !intel_streams_type1_capable(connector))
 			enforce_type0 = true;
 
 		data->streams[data->k].stream_id = intel_conn_to_vcpi(connector);