On Tue, 2009-07-14 at 04:41 +0800, Matthew Garrett wrote:
> Certain hardware will send us events when the backlight brightness
> changes. Add a function to update the value in the core, and
> additionally send a uevent so that userspace can pop up appropriate
> UI. The uevents are flagged depending on whether the update originated
> in the kernel or from userspace, making it easier to only display UI
> at the appropriate time.
>
> Signed-off-by: Matthew Garrett <mjg@xxxxxxxxxx>
> ---
> drivers/video/backlight/backlight.c | 23 +++++++++++++++++++++++
> include/linux/backlight.h | 1 +
> 2 files changed, 24 insertions(+), 0 deletions(-)
>
> diff --git a/drivers/video/backlight/backlight.c b/drivers/video/backlight/backlight.c
> index 157057c..98ab76c 100644
> --- a/drivers/video/backlight/backlight.c
> +++ b/drivers/video/backlight/backlight.c
> @@ -120,6 +120,7 @@ static ssize_t backlight_store_brightness(struct device *dev,
> {
> int rc;
> struct backlight_device *bd = to_backlight_device(dev);
> + char *envp[] = { "SOURCE=userspace", NULL };
> unsigned long brightness;
>
> rc = strict_strtoul(buf, 0, &brightness);
> @@ -142,6 +143,8 @@ static ssize_t backlight_store_brightness(struct device *dev,
> }
> mutex_unlock(&bd->ops_lock);
>
> + kobject_uevent_env(&bd->dev.kobj, KOBJ_CHANGE, envp);
> +
It will be better to send the event to user space only when the
brightness is updated successfully.
> return rc;
> }
>
> @@ -214,6 +217,26 @@ static struct device_attribute bl_device_attributes[] = {
> };
>
> /**
> + * backlight_force_update - tell the backlight subsystem that hardware state
> + * has changed
> + * @bd: the backlight device to update
> + *
> + * Updates the internal state of the backlight in response to a hardware event,
> + * and generate a uevent to notify userspace
> + */
> +void backlight_force_update(struct backlight_device *bd)
> +{
> + char *envp[] = { "SOURCE=kernel", NULL };
> +
> + mutex_lock(&bd->ops_lock);
> + if (bd->ops && bd->ops->get_brightness)
> + bd->props.brightness = bd->ops->get_brightness(bd);
> + mutex_unlock(&bd->ops_lock);
> + kobject_uevent_env(&bd->dev.kobj, KOBJ_CHANGE, envp);
> +}
> +EXPORT_SYMBOL(backlight_force_update);
It seems that the acpi video driver will send the ACPI event to user
space when updating the brightness.
Is it necessary to send the udev-event again?
Thanks.
> +
> +/**
> * backlight_device_register - create and register a new object of
> * backlight_device class.
> * @name: the name of the new object(must be the same as the name of the
> diff --git a/include/linux/backlight.h b/include/linux/backlight.h
> index 79ca2da..8298c43 100644
> --- a/include/linux/backlight.h
> +++ b/include/linux/backlight.h
> @@ -100,6 +100,7 @@ static inline void backlight_update_status(struct backlight_device *bd)
> extern struct backlight_device *backlight_device_register(const char *name,
> struct device *dev, void *devdata, struct backlight_ops *ops);
> extern void backlight_device_unregister(struct backlight_device *bd);
> +extern void backlight_force_update(struct backlight_device *bd);
>
> #define to_backlight_device(obj) container_of(obj, struct backlight_device, dev)
>
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