On Friday, November 09, 2012 11:05 PM Thierry Reding wrote
>
> This function finds the struct backlight_device for a given device tree
> node. A dummy function is provided so that it safely compiles out if OF
> support is disabled.
>
> Signed-off-by: Thierry Reding <thierry.reding@xxxxxxxxxxxxxxxxx>
CC'ed Andrew Morton
Hi Thierry Reding,
The patch itself looks good.
Could you explain when this API is used?
Thank you.
Best regards,
Jingoo Han
> ---
> drivers/video/backlight/backlight.c | 17 +++++++++++++++++
> include/linux/backlight.h | 10 ++++++++++
> 2 files changed, 27 insertions(+)
>
> diff --git a/drivers/video/backlight/backlight.c b/drivers/video/backlight/backlight.c
> index 297db2f..0d1ed4f 100644
> --- a/drivers/video/backlight/backlight.c
> +++ b/drivers/video/backlight/backlight.c
> @@ -370,6 +370,23 @@ void backlight_device_unregister(struct backlight_device *bd)
> }
> EXPORT_SYMBOL(backlight_device_unregister);
>
> +#if IS_ENABLED(CONFIG_OF)
> +static int of_parent_match(struct device *dev, void *data)
> +{
> + return dev->parent && dev->parent->of_node == data;
> +}
> +
> +struct backlight_device *of_find_backlight_by_node(struct device_node *node)
> +{
> + struct device *dev;
> +
> + dev = class_find_device(backlight_class, NULL, node, of_parent_match);
> +
> + return dev ? to_backlight_device(dev) : NULL;
> +}
> +EXPORT_SYMBOL(of_find_backlight_by_node);
> +#endif
> +
> static void __exit backlight_class_exit(void)
> {
> class_destroy(backlight_class);
> diff --git a/include/linux/backlight.h b/include/linux/backlight.h
> index 5ffc6dd..11840e9 100644
> --- a/include/linux/backlight.h
> +++ b/include/linux/backlight.h
> @@ -134,4 +134,14 @@ struct generic_bl_info {
> void (*kick_battery)(void);
> };
>
> +#if IS_ENABLED(CONFIG_OF)
> +struct backlight_device *of_find_backlight_by_node(struct device_node *node);
> +#else
> +static inline struct backlight_device *
> +of_find_backlight_by_node(struct device_node *node)
> +{
> + return NULL;
> +}
> +#endif
> +
> #endif
> --
> 1.8.0
>
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