backlight: Add backlight device (un)registration notification
Some firmware drivers, ie acpi-video want to get themselves out of the
way (in some cases) when their also is a raw backlight device available.
Due to module loading ordering being unknown, acpi-video cannot be certain
that the backlight_device_registered(BACKLIGHT_RAW) it does for this is
the final verdict wrt there being a BACKLIGHT_RAW device.
By adding notification acpi-video can listen for backlight devices showing
up after it has loaded, and unregister its backlight device if desired.
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Acked-by: Jingoo Han <jg1.han@samsung.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
diff --git a/include/linux/backlight.h b/include/linux/backlight.h
index 7264742..adb14a8 100644
--- a/include/linux/backlight.h
+++ b/include/linux/backlight.h
@@ -40,6 +40,11 @@
BACKLIGHT_TYPE_MAX,
};
+enum backlight_notification {
+ BACKLIGHT_REGISTERED,
+ BACKLIGHT_UNREGISTERED,
+};
+
struct backlight_device;
struct fb_info;
@@ -133,6 +138,8 @@
extern void backlight_force_update(struct backlight_device *bd,
enum backlight_update_reason reason);
extern bool backlight_device_registered(enum backlight_type type);
+extern int backlight_register_notifier(struct notifier_block *nb);
+extern int backlight_unregister_notifier(struct notifier_block *nb);
#define to_backlight_device(obj) container_of(obj, struct backlight_device, dev)