Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 3cc6919b authored by Hans de Goede's avatar Hans de Goede Committed by Rafael J. Wysocki
Browse files

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: default avatarHans de Goede <hdegoede@redhat.com>
Acked-by: default avatarJingoo Han <jg1.han@samsung.com>
Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
parent bee56443

drivers/video/backlight/backlight.c

+40 −0
Original line number Diff line number Diff line
@@ -23,6 +23,7 @@ 


static struct list_head backlight_dev_list;

static struct mutex backlight_dev_list_mutex;

static struct blocking_notifier_head backlight_notifier;



static const char *const backlight_types[] = {

	[BACKLIGHT_RAW] = "raw",
@@ -370,6 +371,9 @@ struct backlight_device *backlight_device_register(const char *name, 
	list_add(&new_bd->entry, &backlight_dev_list);

	mutex_unlock(&backlight_dev_list_mutex);



	blocking_notifier_call_chain(&backlight_notifier,

				     BACKLIGHT_REGISTERED, new_bd);



	return new_bd;

}

EXPORT_SYMBOL(backlight_device_register);
@@ -413,6 +417,10 @@ void backlight_device_unregister(struct backlight_device *bd) 
		pmac_backlight = NULL;

	mutex_unlock(&pmac_backlight_mutex);

#endif



	blocking_notifier_call_chain(&backlight_notifier,

				     BACKLIGHT_UNREGISTERED, bd);



	mutex_lock(&bd->ops_lock);

	bd->ops = NULL;

	mutex_unlock(&bd->ops_lock);
@@ -437,6 +445,36 @@ static int devm_backlight_device_match(struct device *dev, void *res, 
	return *r == data;

}



/**

 * backlight_register_notifier - get notified of backlight (un)registration

 * @nb: notifier block with the notifier to call on backlight (un)registration

 *

 * @return 0 on success, otherwise a negative error code

 *

 * Register a notifier to get notified when backlight devices get registered

 * or unregistered.

 */

int backlight_register_notifier(struct notifier_block *nb)

{

	return blocking_notifier_chain_register(&backlight_notifier, nb);

}

EXPORT_SYMBOL(backlight_register_notifier);



/**

 * backlight_unregister_notifier - unregister a backlight notifier

 * @nb: notifier block to unregister

 *

 * @return 0 on success, otherwise a negative error code

 *

 * Register a notifier to get notified when backlight devices get registered

 * or unregistered.

 */

int backlight_unregister_notifier(struct notifier_block *nb)

{

	return blocking_notifier_chain_unregister(&backlight_notifier, nb);

}

EXPORT_SYMBOL(backlight_unregister_notifier);



/**

 * devm_backlight_device_register - resource managed backlight_device_register()

 * @dev: the device to register
@@ -544,6 +582,8 @@ static int __init backlight_class_init(void) 
	backlight_class->pm = &backlight_class_dev_pm_ops;

	INIT_LIST_HEAD(&backlight_dev_list);

	mutex_init(&backlight_dev_list_mutex);

	BLOCKING_INIT_NOTIFIER_HEAD(&backlight_notifier);



	return 0;

}

include/linux/backlight.h

+7 −0
Original line number Diff line number Diff line
@@ -40,6 +40,11 @@ enum backlight_type { 
	BACKLIGHT_TYPE_MAX,

};



enum backlight_notification {

	BACKLIGHT_REGISTERED,

	BACKLIGHT_UNREGISTERED,

};



struct backlight_device;

struct fb_info;
@@ -133,6 +138,8 @@ extern void devm_backlight_device_unregister(struct device *dev, 
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)