On 03/08/2012 07:52 AM, Donghwa Lee wrote:
> In backlight class, update_status() callback function is mostly used to change
> backlight brightness. When platform enter the dimming state, it is usually used.
> But, I think dimming state can be defined variety of method including brightness.
> So, it is need to differentiated node from brightness node.
What do you mean by dimming? Completely blank the display or just lower the
brightness to a certain level > 0? In the former case the bl_power sysfs
node already exposes such functionality. In the later case can you give an
example how this will be used and how a typical driver would implement this
functionality?
>
> In set_dimming() callback function, developers can define variety dimming functions.
>
> Signed-off-by: Donghwa Lee <dh09.lee@xxxxxxxxxxx>
> Signed-off-by: Inki Dae <inki.dae@xxxxxxxxxxx>
> Signed-off-by: Kyungmin Park <kyungmin.park@xxxxxxxxxxx>
> ---
> drivers/video/backlight/backlight.c | 37 +++++++++++++++++++++++++++++++++++
> include/linux/backlight.h | 9 ++++++++
> 2 files changed, 46 insertions(+), 0 deletions(-)
>
> diff --git a/drivers/video/backlight/backlight.c b/drivers/video/backlight/backlight.c
> index bf5b1ec..44a77e4 100644
> --- a/drivers/video/backlight/backlight.c
> +++ b/drivers/video/backlight/backlight.c
> @@ -101,6 +101,43 @@ static void backlight_generate_event(struct backlight_device *bd,
> sysfs_notify(&bd->dev.kobj, NULL, "actual_brightness");
> }
>
> +static ssize_t backlight_store_dimming(struct device *dev,
> + struct device_attribute *attr, const char *buf, size_t count)
> +{
> + int rc;
> + struct backlight_device *bd = to_backlight_device(dev);
> + unsigned long dimming;
> +
> + rc = strict_strtoul(buf, 0, &dimming);
> + if (rc)
> + return rc;
> +
> + if (dimming < 0)
> + rc = -EINVAL;
> + else {
> + pr_debug("set dimming mode\n");
> +
> + if (dimming)
> + bd->props.dimming = true;
> + else
> + bd->props.dimming = false;
> +
> + backlight_set_dimming(bd);
> +
> + rc = count;
> + }
> +
> + return rc;
> +}
> +
> +static ssize_t backlight_show_dimming(struct device *dev,
> + struct device_attribute *attr,char *buf)
> +{
> + struct backlight_device *bd = to_backlight_device(dev);
> +
> + return sprintf(buf, "%d\n", bd->props.dimming);
> +}
> +
> static ssize_t backlight_show_power(struct device *dev,
> struct device_attribute *attr, char *buf)
> {
> diff --git a/include/linux/backlight.h b/include/linux/backlight.h
> index 5ffc6dd..823717e 100644
> --- a/include/linux/backlight.h
> +++ b/include/linux/backlight.h
> @@ -55,10 +55,13 @@ struct backlight_ops {
> /* Check if given framebuffer device is the one bound to this backlight;
> return 0 if not, !=0 if it is. If NULL, backlight always matches the fb. */
> int (*check_fb)(struct backlight_device *, struct fb_info *);
> + /* Notify the backlight driver to enter the dimming state */
> + int (*set_dimming)(struct backlight_device *);
> };
>
> /* This structure defines all the properties of a backlight */
> struct backlight_properties {
> + bool dimming;
> /* Current User requested brightness (0 - max_brightness) */
> int brightness;
> /* Maximal value for brightness (read-only) */
> @@ -111,6 +114,12 @@ static inline void backlight_update_status(struct backlight_device *bd)
> mutex_unlock(&bd->update_lock);
> }
>
> +static inline void backlight_set_dimming(struct backlight_device *bd)
> +{
> + if (bd->ops && bd->ops->set_dimming)
> + bd->ops->set_dimming(bd);
> +}
> +
> extern struct backlight_device *backlight_device_register(const char *name,
> struct device *dev, void *devdata, const struct backlight_ops *ops,
> const struct backlight_properties *props);
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