Re: [PATCH RFC 3/4] backlight: add kernel-internal backlight API

[Thierry Reding]

On Wed, Sep 10, 2014 at 05:54:22PM +0200, David Herrmann wrote:
[...]
> +void backlight_set_brightness(struct backlight_device *bd, unsigned int value,
> +			      enum backlight_update_reason reason)
> +{
> +	mutex_lock(&bd->ops_lock);
> +	if (bd->ops) {
> +		value = clamp(value, 0U, (unsigned)bd->props.max_brightness);

max_brightness should really be unsigned to begin with...

> +		pr_debug("set brightness to %u\n", value);

dev_dbg(&bd->dev, ...)?

> diff --git a/include/linux/backlight.h b/include/linux/backlight.h
> index adb14a8..bcc0dec 100644
> --- a/include/linux/backlight.h
> +++ b/include/linux/backlight.h
> @@ -141,6 +141,22 @@ extern bool backlight_device_registered(enum backlight_type type);
>  extern int backlight_register_notifier(struct notifier_block *nb);
>  extern int backlight_unregister_notifier(struct notifier_block *nb);
>  
> +struct backlight_device *backlight_device_lookup(const char *name);
> +void backlight_set_brightness(struct backlight_device *bd, unsigned int value,
> +			      enum backlight_update_reason reason);
> +
> +static inline void backlight_device_ref(struct backlight_device *bd)
> +{
> +	if (bd)
> +		get_device(&bd->dev);
> +}

Perhaps for consistency with get_device() this should return bd? That
way you can chain things like so:

	priv->backlight = backlight_device_ref(bd);

Thierry

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