drm/i915/hdcp: Adjust timeout for read in DPMST Scenario

For dpmst hdcp scenario increase the message timeout based
on the number of ports connected as each port needs to be
validated and each will take the prescribed amount of time
for the respective msg_id and total timeout will be
original_timeout * num_ports.

--v2
-Add justification for Adjusting the timeout [Arun]
Signed-off-by: Suraj Kandpal <suraj.kandpal@intel.com>
Reviewed-by: Arun R Murthy <arun.r.murthy@intel.com>
Signed-off-by: Uma Shankar <uma.shankar@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230828063401.600414-5-suraj.kandpal@intel.com

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

@@ -560,9 +560,15 @@ int intel_dp_hdcp2_read_msg(struct intel_connector *connector,
 		      DP_AUX_MAX_PAYLOAD_BYTES : bytes_to_recv;
 
 		/* Entire msg read timeout since initiate of msg read */
-		if (bytes_to_recv == size - 1 && hdcp2_msg_data->msg_read_timeout > 0)
+		if (bytes_to_recv == size - 1 && hdcp2_msg_data->msg_read_timeout > 0) {
+			if (intel_encoder_is_mst(connector->encoder))
+				msg_end = ktime_add_ms(ktime_get_raw(),
+						       hdcp2_msg_data->msg_read_timeout *
+						       connector->port->parent->num_ports);
+			else
 				msg_end = ktime_add_ms(ktime_get_raw(),
 						       hdcp2_msg_data->msg_read_timeout);
+		}
 
 		ret = drm_dp_dpcd_read(aux, offset,
 				       (void *)byte, len);