Hi,
On 05/22/2014 01:31 AM, Rafael J. Wysocki wrote:
On Wednesday, May 21, 2014 03:39:54 PM Hans de Goede wrote:
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
Backlight maintainer's ACK is requisite here.
Agreed, which is why I send this set to all 3 the backlight maintainers directly on both postings.
What may be helpful for them is to hear from you if you're ok with the acpi-video bits which are actually going to use this, since those will be the only user of the new backlight api (for now).
Thanks & Regardsm
Hans
drivers/video/backlight/backlight.c | 40 +++++++++++++++++++++++++++++++++++++ include/linux/backlight.h | 7 +++++++ 2 files changed, 47 insertions(+)
diff --git a/drivers/video/backlight/backlight.c b/drivers/video/backlight/backlight.c index bd2172c..4280890 100644 --- a/drivers/video/backlight/backlight.c +++ b/drivers/video/backlight/backlight.c @@ -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);
@@ -438,6 +446,36 @@ static int devm_backlight_device_match(struct device *dev, void *res, }
/**
- 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
- @name: the name of the device
@@ -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;
}
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 @@ 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)