[PATCH v3 2/2] drm/tinydrm: Add devres versions of drm_of_find_backlight

[Noralf Trønnes]

Den 28.09.2017 11.15, skrev Meghana Madhyastha:
> Add devm_drm_of_find_backlight and the corresponding release
> function because some drivers such as tinydrm use devres versions
> of functions for requiring device resources.
>
> Signed-off-by: Meghana Madhyastha <meghana.madhyastha at gmail.com>
> ---
> Changes in v3:
> -None
>
>   drivers/gpu/drm/drm_of.c | 48 ++++++++++++++++++++++++++++++++++++++++++++++++
>   include/drm/drm_of.h     |  2 ++
>   2 files changed, 50 insertions(+)
>
> diff --git a/drivers/gpu/drm/drm_of.c b/drivers/gpu/drm/drm_of.c
> index d878d3a..238e8e5 100644
> --- a/drivers/gpu/drm/drm_of.c
> +++ b/drivers/gpu/drm/drm_of.c
> @@ -304,3 +304,51 @@ struct backlight_device *drm_of_find_backlight(struct device *dev)
>   	return backlight;
>   }
>   EXPORT_SYMBOL(drm_of_find_backlight);
> +
> +/**
> + * devm_drm_of_find_backlight_release - Release backlight device
> + * @dev: Device
> + *
> + * This is the release function corresponding to the devm_drm_of_find_backlight.
> + * Each devres entry is associated with a release function.
> + */

This is an internal function so no need for docs or exporting. I know
that some devm_ functions have explicit release functions, but I don't
think this is necessary since those users can just use
drm_of_find_backlight() directly instead.

> +static void devm_drm_of_find_backlight_release(void *data)
> +{
> +	put_device(data);
> +}
> +EXPORT_SYMBOL(devm_drm_of_find_backlight_release);
> +
> +/**
> + * devm_drm_of_find_backlight - Find backlight device in device-tree
> + * devres version of the function
> + * @dev: Device
> + *
> + * This is the devres version of the function drm_of_find_backlight.
> + * Some drivers such as tinydrm use devres versions of functions for

No need to mention tinydrm here.

> + * requiring device resources.
> + *
> + * Returns:
> + * NULL if there's no backlight property.
> + * Error pointer -EPROBE_DEFER if the DT node is found, but no backlight device
> + * is found.
> + * If the backlight device is found, a pointer to the structure is returned.
> + */
> +struct backlight_device *devm_drm_of_find_backlight(struct device *dev)
> +{
> +	struct backlight_device *backlight;
> +	int ret;
> +
> +	backlight = drm_of_find_backlight(dev);
> +	if (IS_ERR_OR_NULL(backlight))
> +		return backlight;
> +
> +	ret = devm_add_action(dev, devm_drm_of_find_backlight_release,
> +			      &backlight->dev);
> +	if (ret) {
> +		put_device(&backlight->dev);
> +		return ERR_PTR(ret);
> +	}
> +
> +	return backlight;
> +}
> +EXPORT_SYMBOL(devm_drm_of_find_backlight);
> diff --git a/include/drm/drm_of.h b/include/drm/drm_of.h
> index e8fba5b..071fb3b 100644
> --- a/include/drm/drm_of.h
> +++ b/include/drm/drm_of.h
> @@ -30,7 +30,9 @@ int drm_of_find_panel_or_bridge(const struct device_node *np,
>   				struct drm_panel **panel,
>   				struct drm_bridge **bridge);
>   struct backlight_device *drm_of_find_backlight(struct device *dev);
> +struct backlight_device *devm_drm_of_find_backlight(struct device *dev);
>   #else

We need a dummy version of devm_drm_of_find_backlight() here that
returns NULL as in the previous patch.

> +static void devm_drm_of_find_backlight_release(void *data);

And this isn't needed as explained above.
>   static inline uint32_t drm_of_find_possible_crtcs(struct drm_device *dev,
>   						  struct device_node *port)
>   {

I'd appreciate if you could also switch mi0283qt over to this helper :-)

Noralf.