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Subject: Re: [PATCH v16 05/10] video: backlight: Add devres versions of
 of_find_backlight
To:     Meghana Madhyastha <meghana.madhyastha@gmail.com>,
        Lee Jones <lee.jones@linaro.org>,
        Jingoo Han <jingoohan1@gmail.com>,
        Thierry Reding <thierry.reding@gmail.com>,
        =?UTF-8?Q?Noralf_Tr=c3=b8nnes?= <noralf@tronnes.org>,
        Tomi Valkeinen <tomi.valkeinen@ti.com>,
        Daniel Vetter <daniel.vetter@intel.com>,
        Sean Paul <seanpaul@chromium.org>,
        dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org
References: <cover.1516098341.git.meghana.madhyastha@gmail.com>
 <87984b3cb205b19d50f3093e34c6dc8d8179b768.1516098341.git.meghana.madhyastha@gmail.com>
From:   Daniel Thompson <daniel.thompson@linaro.org>
Message-ID: <8e3ad1f2-b4df-10a4-844c-8bbc8801aaf5@linaro.org>
Date:   Wed, 17 Jan 2018 17:09:57 +0000
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On 16/01/18 10:34, Meghana Madhyastha wrote:
> Add devm_of_find_backlight and the corresponding release
> function because some drivers use devres versions of functions
> for acquiring device resources.
> 
> Signed-off-by: Meghana Madhyastha <meghana.madhyastha@gmail.com>
> ---
>   drivers/video/backlight/backlight.c | 29 +++++++++++++++++++++++++++++
>   include/linux/backlight.h           |  7 +++++++
>   2 files changed, 36 insertions(+)
> 
> diff --git a/drivers/video/backlight/backlight.c b/drivers/video/backlight/backlight.c
> index 7e4a5d77d..b3f76945f 100644
> --- a/drivers/video/backlight/backlight.c
> +++ b/drivers/video/backlight/backlight.c
> @@ -620,6 +620,35 @@ struct backlight_device *of_find_backlight(struct device *dev)
>   }
>   EXPORT_SYMBOL(of_find_backlight);
>   
> +static void devm_backlight_put(void *data)
> +{
> +	backlight_put(data);

Shouldn't this be using devres_release()?


> +}
> +
> +/**
> +  * devm_of_find_backlight - Resource-managed of_find_backlight()
> +  * @dev: Device
> +  *
> +  * Device managed version of of_find_backlight(). The reference on the backlight
> +  * device is automatically dropped on driver detach.
> +  */
> +struct backlight_device *devm_of_find_backlight(struct device *dev)
> +{
> +	struct backlight_device *bd;
> +	int ret;
> +
> +	bd = of_find_backlight(dev);
> +	if (IS_ERR_OR_NULL(bd))
> +		return bd;
> +	ret = devm_add_action(dev, devm_backlight_put, bd);
> +	if (ret) {
> +		backlight_put(bd);
> +		return ERR_PTR(ret);
> +	}
> +	return bd;
> +}
> +EXPORT_SYMBOL(devm_of_find_backlight);
> +
>   static void __exit backlight_class_exit(void)
>   {
>   	class_destroy(backlight_class);
> diff --git a/include/linux/backlight.h b/include/linux/backlight.h
> index 32ea510da..1d373f5a6 100644
> --- a/include/linux/backlight.h
> +++ b/include/linux/backlight.h
> @@ -215,11 +215,18 @@ of_find_backlight_by_node(struct device_node *node)
>   
>   #if IS_ENABLED(CONFIG_BACKLIGHT_CLASS_DEVICE)
>   struct backlight_device *of_find_backlight(struct device *dev);
> +struct backlight_device *devm_of_find_backlight(struct device *dev);
>   #else
>   static inline struct backlight_device *of_find_backlight(struct device *dev)
>   {
>   	return NULL;
>   }
> +
> +static inline struct backlight_device *
> +devm_of_find_backlight(struct device *dev)
> +{
> +	return NULL;
> +}
>   #endif
>   
>   #endif
>