[Outreachy kernel] [PATCH v13 3/3] drm/tinydrm: Add devres versions of backlight_get

[Sean Paul]

On Fri, Oct 13, 2017 at 04:12:55PM +0530, Meghana Madhyastha wrote:
> Add devm_backlight_get and the corresponding release
> function because some drivers use devres versions of functions
> for requiring device resources.
> 

This patch looks fine, just update the names to be consistent with the previous
version and account for backlight_put not being present.

Sean

> Signed-off-by: Meghana Madhyastha <meghana.madhyastha at gmail.com>
> ---
> Changes in v13:
>  -Add devm_backlight_put to backlight.c
> 
>  drivers/gpu/drm/tinydrm/mi0283qt.c  |  2 +-
>  drivers/video/backlight/backlight.c | 31 +++++++++++++++++++++++++++++++
>  include/linux/backlight.h           |  6 ++++++
>  3 files changed, 38 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/tinydrm/mi0283qt.c b/drivers/gpu/drm/tinydrm/mi0283qt.c
> index a932185..e3e7583 100644
> --- a/drivers/gpu/drm/tinydrm/mi0283qt.c
> +++ b/drivers/gpu/drm/tinydrm/mi0283qt.c
> @@ -189,7 +189,7 @@ static int mi0283qt_probe(struct spi_device *spi)
>  	if (IS_ERR(mipi->regulator))
>  		return PTR_ERR(mipi->regulator);
>  
> -	mipi->backlight = backlight_get(dev);
> +	mipi->backlight = devm_backlight_get(dev);
>  	if (IS_ERR(mipi->backlight))
>  		return PTR_ERR(mipi->backlight);
>  
> diff --git a/drivers/video/backlight/backlight.c b/drivers/video/backlight/backlight.c
> index c4e94d0..b6c505a 100644
> --- a/drivers/video/backlight/backlight.c
> +++ b/drivers/video/backlight/backlight.c
> @@ -617,6 +617,37 @@ struct backlight_device *backlight_get(struct device *dev)
>  }
>  EXPORT_SYMBOL(backlight_get);
>  
> +static void devm_backlight_put(void *data)
> +{
> +	backlight_put(data);
> +}
> +
> +/**
> + * devm_backlight_get - Resource-managed backlight_get()
> + * @dev: Device
> + *
> + * Device managed version of backlight_get(). The reference on the backlight
> + * device is automatically dropped on driver detach.
> + */
> +struct backlight_device *devm_backlight_get(struct device *dev)
> +{
> +	struct backlight_device *bd;
> +	int ret;
> +
> +	bd = backlight_get(dev);
> +	if (!bd)
> +		return NULL;
> +
> +	ret = devm_add_action(dev, devm_backlight_put, bd);
> +	if (ret) {
> +		backlight_put(bd);
> +		return ERR_PTR(ret);
> +	}
> +
> +	return bd;
> +}
> +EXPORT_SYMBOL(devm_backlight_get);
> +
>  static void __exit backlight_class_exit(void)
>  {
>  	class_destroy(backlight_class);
> diff --git a/include/linux/backlight.h b/include/linux/backlight.h
> index 987a6d7..8db9ba9 100644
> --- a/include/linux/backlight.h
> +++ b/include/linux/backlight.h
> @@ -214,11 +214,17 @@ of_find_backlight_by_node(struct device_node *node)
>  
>  #if IS_ENABLED(CONFIG_BACKLIGHT_CLASS_DEVICE)
>  struct backlight_device *backlight_get(struct device *dev);
> +struct backlight_device *devm_backlight_get(struct device *dev);
>  #else
>  static inline struct backlight_device *backlight_get(struct device *dev)
>  {
>  	return NULL;
>  }
> +
> +static inline struct backlight_device *devm_backlight_get(struct device *dev)
> +{
> +	return NULL;
> +}
>  #endif
>  
>  #endif
> -- 
> 2.7.4
> 
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-- 
Sean Paul, Software Engineer, Google / Chromium OS