i915: Fix opregion notifications

opregion-based platforms will send ACPI video event 0x80 for a range of
notification types for legacy compatibility. This is interpreted as a
display switch event, which may not be appropriate in the circumstances.
When we receive such an event we should make sure that the platform is
genuinely requesting a display switch before passing that event through
to userspace.
Signed-off-by: NMatthew Garrett <mjg@redhat.com>
Tested-by: NAdam Jackson <ajax@redhat.com>
Signed-off-by: NKeith Packard <keithp@keithp.com>

drivers/acpi/video.c

@@ -46,7 +46,6 @@
 
 #define PREFIX "ACPI: "
 
-#define ACPI_VIDEO_CLASS		"video"
 #define ACPI_VIDEO_BUS_NAME		"Video Bus"
 #define ACPI_VIDEO_DEVICE_NAME		"Video Device"
 #define ACPI_VIDEO_NOTIFY_SWITCH	0x80
@@ -1445,6 +1444,7 @@ static void acpi_video_bus_notify(struct acpi_device *device, u32 event)
 	case ACPI_VIDEO_NOTIFY_SWITCH:	/* User requested a switch,
 					 * most likely via hotkey. */
 		acpi_bus_generate_proc_event(device, event, 0);
+		if (!acpi_notifier_call_chain(device, event, 0))
 			keycode = KEY_SWITCHVIDEOMODE;
 		break;
 
@@ -1475,6 +1475,7 @@ static void acpi_video_bus_notify(struct acpi_device *device, u32 event)
 		break;
 	}
 
+	if (event != ACPI_VIDEO_NOTIFY_SWITCH)
 		acpi_notifier_call_chain(device, event, 0);
 
 	if (keycode) {

drivers/gpu/drm/i915/intel_opregion.c

@@ -297,19 +297,26 @@ static int intel_opregion_video_event(struct notifier_block *nb,
 	/* The only video events relevant to opregion are 0x80. These indicate
 	   either a docking event, lid switch or display switch request. In
 	   Linux, these are handled by the dock, button and video drivers.
-	   We might want to fix the video driver to be opregion-aware in
-	   future, but right now we just indicate to the firmware that the
-	   request has been handled */
+	*/
 
 	struct opregion_acpi *acpi;
+	struct acpi_bus_event *event = data;
+	int ret = NOTIFY_OK;
+
+	if (strcmp(event->device_class, ACPI_VIDEO_CLASS) != 0)
+		return NOTIFY_DONE;
 
 	if (!system_opregion)
 		return NOTIFY_DONE;
 
 	acpi = system_opregion->acpi;
+
+	if (event->type == 0x80 && !(acpi->cevt & 0x1))
+		ret = NOTIFY_BAD;
+
 	acpi->csts = 0;
 
-	return NOTIFY_OK;
+	return ret;
 }
 
 static struct notifier_block intel_opregion_notifier = {

include/acpi/video.h

@@ -5,6 +5,8 @@
 
 struct acpi_device;
 
+#define ACPI_VIDEO_CLASS	"video"
+
 #define ACPI_VIDEO_DISPLAY_CRT  1
 #define ACPI_VIDEO_DISPLAY_TV   2
 #define ACPI_VIDEO_DISPLAY_DVI  3