drm/i915/opregion: early exit from encoder notify if SWSCI isn't there

Newer platforms aren't supposed to have mailbox #2 or SWSCI
support. Bail out early from encoder notify if that is the case,
skipping the out-of-bounds checks and debug messages.

Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/82f63313057ed2d96856b3f8d76536826a897bc7.1644489329.git.jani.nikula@intel.com

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

@@ -358,11 +358,17 @@ int intel_opregion_notify_encoder(struct intel_encoder *intel_encoder,
 	u32 parm = 0;
 	u32 type = 0;
 	u32 port;
+	int ret;
 
 	/* don't care about old stuff for now */
 	if (!HAS_DDI(dev_priv))
 		return 0;
 
+	/* Avoid port out of bounds checks if SWSCI isn't there. */
+	ret = check_swsci_function(dev_priv, SWSCI_SBCB_DISPLAY_POWER_STATE);
+	if (ret)
+		return ret;
+
 	if (intel_encoder->type == INTEL_OUTPUT_DSI)
 		port = 0;
 	else