drm/radeon: block the keypress on ATIF events

The AMD ACPI interface may use ACPI_VIDEO_NOTIFY_PROBE to signal SBIOS
requests; block the keypress in this case since the user did not
actually press the mode switch key.

Signed-off-by: Luca Tettamanti <kronos.it@gmail.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/radeon/radeon_acpi.c

@@ -301,7 +301,12 @@ int radeon_atif_handler(struct radeon_device *rdev,
 	}
 	/* TODO: check other events */
 
-	return NOTIFY_OK;
+	/* We've handled the event, stop the notifier chain. The ACPI interface
+	 * overloads ACPI_VIDEO_NOTIFY_PROBE, we don't want to send that to
+	 * userspace if the event was generated only to signal a SBIOS
+	 * request.
+	 */
+	return NOTIFY_BAD;
 }
 
 static int radeon_acpi_event(struct notifier_block *nb,