On Tuesday, October 08, 2013 02:39:58 PM Aaron Lu wrote:
> Introduce a new API for modules to query if a specific type of backlight
> device has been registered. This is useful for some backlight device
> provider module(e.g. ACPI video) to know if a native control
> interface(e.g. the interface created by i915) is available and then do
> things accordingly(e.g. avoid register its own on Win8 systems).
>
> Signed-off-by: Aaron Lu <aaron.lu@xxxxxxxxx>
> Tested-by: Igor Gnatenko <i.gnatenko.brain@xxxxxxxxx>
> Tested-by: Yves-Alexis Perez <corsac@xxxxxxxxxx>
> Tested-by: Mika Westerberg <mika.westerberg@xxxxxxxxxxxxxxx>
> ---
> drivers/video/backlight/backlight.c | 31 +++++++++++++++++++++++++++++++
> include/linux/backlight.h | 4 ++++
> 2 files changed, 35 insertions(+)
>
> diff --git a/drivers/video/backlight/backlight.c b/drivers/video/backlight/backlight.c
> index 94a403a..bf2d71d 100644
> --- a/drivers/video/backlight/backlight.c
> +++ b/drivers/video/backlight/backlight.c
> @@ -21,6 +21,9 @@
> #include <asm/backlight.h>
> #endif
>
> +static struct list_head bd_list_head;
> +static struct mutex bd_list_mutex;
I'd prefer these two things to be called backlight_dev_list and
backlight_dev_list_mutex, respectively.
> +
> static const char *const backlight_types[] = {
> [BACKLIGHT_RAW] = "raw",
> [BACKLIGHT_PLATFORM] = "platform",
> @@ -349,10 +352,32 @@ struct backlight_device *backlight_device_register(const char *name,
> mutex_unlock(&pmac_backlight_mutex);
> #endif
>
> + mutex_lock(&bd_list_mutex);
> + list_add(&new_bd->entry, &bd_list_head);
> + mutex_unlock(&bd_list_mutex);
> +
> return new_bd;
> }
> EXPORT_SYMBOL(backlight_device_register);
>
> +bool backlight_device_registered(enum backlight_type type)
> +{
> + bool found = false;
> + struct backlight_device *bd;
> +
> + mutex_lock(&bd_list_mutex);
> + list_for_each_entry(bd, &bd_list_head, entry) {
> + if (bd->props.type == type) {
> + found = true;
> + break;
> + }
> + }
Isn't it useful to be able to register more than one backlight device of the
same type sometimes?
> + mutex_unlock(&bd_list_mutex);
> +
> + return found;
> +}
> +EXPORT_SYMBOL(backlight_device_registered);
> +
> /**
> * backlight_device_unregister - unregisters a backlight device object.
> * @bd: the backlight device object to be unregistered and freed.
> @@ -364,6 +389,10 @@ void backlight_device_unregister(struct backlight_device *bd)
> if (!bd)
> return;
>
> + mutex_lock(&bd_list_mutex);
> + list_del(&bd->entry);
> + mutex_unlock(&bd_list_mutex);
> +
> #ifdef CONFIG_PMAC_BACKLIGHT
> mutex_lock(&pmac_backlight_mutex);
> if (pmac_backlight == bd)
> @@ -499,6 +528,8 @@ static int __init backlight_class_init(void)
>
> backlight_class->dev_groups = bl_device_groups;
> backlight_class->pm = &backlight_class_dev_pm_ops;
> + INIT_LIST_HEAD(&bd_list_head);
> + mutex_init(&bd_list_mutex);
> return 0;
> }
>
> diff --git a/include/linux/backlight.h b/include/linux/backlight.h
> index 53b7794..5f9cd96 100644
> --- a/include/linux/backlight.h
> +++ b/include/linux/backlight.h
> @@ -100,6 +100,9 @@ struct backlight_device {
> /* The framebuffer notifier block */
> struct notifier_block fb_notif;
>
> + /* list entry of all registered backlight devices */
> + struct list_head entry;
> +
> struct device dev;
> };
>
> @@ -123,6 +126,7 @@ extern void devm_backlight_device_unregister(struct device *dev,
> struct backlight_device *bd);
> extern void backlight_force_update(struct backlight_device *bd,
> enum backlight_update_reason reason);
> +extern bool backlight_device_registered(enum backlight_type type);
>
> #define to_backlight_device(obj) container_of(obj, struct backlight_device, dev)
Thanks!
--
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.
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