ACPI: video: Remove code to unregister acpi_video backlight when a native backlight registers

Remove the code to unregister acpi_video backlight devices when
a native backlight device gets registered later.

Now that the acpi_video backlight device registration is a separate step
which runs later, after the drm/kms driver is done setting up its own
native backlight device, it is no longer necessary to monitor for a
native (BACKLIGHT_RAW) device showing up later and to then unregister
the acpi_video backlight device(s).
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>

drivers/acpi/acpi_video.c

@@ -94,7 +94,6 @@ static void acpi_video_bus_notify(struct acpi_device *device, u32 event);
 static void acpi_video_bus_register_backlight_work(struct work_struct *ignored);
 static DECLARE_DELAYED_WORK(video_bus_register_backlight_work,
 			    acpi_video_bus_register_backlight_work);
-void acpi_video_detect_exit(void);
 
 /*
  * Indices in the _BCL method response: the first two items are special,
@@ -2342,7 +2341,6 @@ static int __init acpi_video_init(void)
 
 static void __exit acpi_video_exit(void)
 {
-	acpi_video_detect_exit();
 	acpi_video_unregister();
 }
 

drivers/acpi/video_detect.c

@@ -38,10 +38,6 @@
 
 void acpi_video_unregister_backlight(void);
 
-static bool backlight_notifier_registered;
-static struct notifier_block backlight_nb;
-static struct work_struct backlight_notify_work;
-
 static enum acpi_backlight_type acpi_backlight_cmdline = acpi_backlight_undef;
 static enum acpi_backlight_type acpi_backlight_dmi = acpi_backlight_undef;
 
@@ -538,26 +534,6 @@ static const struct dmi_system_id video_detect_dmi_table[] = {
 	{ },
 };
 
-/* This uses a workqueue to avoid various locking ordering issues */
-static void acpi_video_backlight_notify_work(struct work_struct *work)
-{
-	if (acpi_video_get_backlight_type() != acpi_backlight_video)
-		acpi_video_unregister_backlight();
-}
-
-static int acpi_video_backlight_notify(struct notifier_block *nb,
-				       unsigned long val, void *bd)
-{
-	struct backlight_device *backlight = bd;
-
-	/* A raw bl registering may change video -> native */
-	if (backlight->props.type == BACKLIGHT_RAW &&
-	    val == BACKLIGHT_REGISTERED)
-		schedule_work(&backlight_notify_work);
-
-	return NOTIFY_OK;
-}
-
 /*
  * Determine which type of backlight interface to use on this system,
  * First check cmdline, then dmi quirks, then do autodetect.
@@ -587,12 +563,6 @@ static enum acpi_backlight_type __acpi_video_get_backlight_type(bool native)
 		acpi_walk_namespace(ACPI_TYPE_DEVICE, ACPI_ROOT_OBJECT,
 				    ACPI_UINT32_MAX, find_video, NULL,
 				    &video_caps, NULL);
-		INIT_WORK(&backlight_notify_work,
-			  acpi_video_backlight_notify_work);
-		backlight_nb.notifier_call = acpi_video_backlight_notify;
-		backlight_nb.priority = 0;
-		if (backlight_register_notifier(&backlight_nb) == 0)
-			backlight_notifier_registered = true;
 		init_done = true;
 	}
 	if (native)
@@ -639,9 +609,3 @@ void acpi_video_set_dmi_backlight_type(enum acpi_backlight_type type)
 		acpi_video_unregister_backlight();
 }
 EXPORT_SYMBOL(acpi_video_set_dmi_backlight_type);
-
-void __exit acpi_video_detect_exit(void)
-{
-	if (backlight_notifier_registered)
-		backlight_unregister_notifier(&backlight_nb);
-}