On Mon, Sep 22, 2014 at 8:21 AM, Jacek Anaszewski
<j.anaszewski@xxxxxxxxxxx> wrote:
> This patch prepares ground for addition of LED Flash Class extension to
> the LED subsystem. Since turning the torch on must have guaranteed
> immediate effect the brightness_set op can't be used for it. Drivers must
> schedule a work queue task in this op to be compatible with led-triggers,
> which call brightess_set from timer irqs. In order to address this
> limitation a torch_brightness_set op and led_set_torch_brightness API
> is introduced. Setting brightness sysfs attribute will result in calling
> brightness_set op for LED Class devices and torch_brightness_set op for
> LED Flash Class devices, whereas triggers will still call brightness
> op in both cases.
>
Although this torch API is for torch, but I think we can make it more
generic and other use case can benefit from this change.
What about this?
Add 2 flags:
1. SET_BRIGHTNESS_ASYNC
2. SET_BRIGHTNESS_SYNC
Then move old API to
__led_set_brightness(led_cdev, state);
led_set_brightness_async();
And add a new API like
led_set_bightness_sync();
Then for torch use case, we use led_set_brightness_sync() API.
-Bryan
> Signed-off-by: Jacek Anaszewski <j.anaszewski@xxxxxxxxxxx>
> Acked-by: Kyungmin Park <kyungmin.park@xxxxxxxxxxx>
> Cc: Bryan Wu <cooloney@xxxxxxxxx>
> Cc: Richard Purdie <rpurdie@xxxxxxxxx>
> ---
> drivers/leds/led-class.c | 9 +++++++--
> drivers/leds/led-core.c | 14 ++++++++++++++
> include/linux/leds.h | 21 +++++++++++++++++++++
> 3 files changed, 42 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/leds/led-class.c b/drivers/leds/led-class.c
> index a39ca8f..5a11a07 100644
> --- a/drivers/leds/led-class.c
> +++ b/drivers/leds/led-class.c
> @@ -54,9 +54,14 @@ static ssize_t brightness_store(struct device *dev,
>
> if (state == LED_OFF)
> led_trigger_remove(led_cdev);
> - __led_set_brightness(led_cdev, state);
>
> - ret = size;
> + if (led_cdev->flags & LED_DEV_CAP_TORCH)
> + ret = led_set_torch_brightness(led_cdev, state);
> + else
> + __led_set_brightness(led_cdev, state);
> +
> + if (!ret)
> + ret = size;
> unlock:
> mutex_unlock(&led_cdev->led_access);
> return ret;
> diff --git a/drivers/leds/led-core.c b/drivers/leds/led-core.c
> index cca86ab..c6d8288 100644
> --- a/drivers/leds/led-core.c
> +++ b/drivers/leds/led-core.c
> @@ -143,6 +143,20 @@ int led_update_brightness(struct led_classdev *led_cdev)
> }
> EXPORT_SYMBOL(led_update_brightness);
>
> +int led_set_torch_brightness(struct led_classdev *led_cdev,
> + enum led_brightness brightness)
> +{
> + int ret = 0;
> +
> + led_cdev->brightness = min(brightness, led_cdev->max_brightness);
> +
> + if (!(led_cdev->flags & LED_SUSPENDED))
> + ret = led_cdev->torch_brightness_set(led_cdev,
> + led_cdev->brightness);
> + return ret;
> +}
> +EXPORT_SYMBOL_GPL(led_set_torch_brightness);
> +
> /* Caller must ensure led_cdev->led_access held */
> void led_sysfs_disable(struct led_classdev *led_cdev)
> {
> diff --git a/include/linux/leds.h b/include/linux/leds.h
> index 44c8a98..bc2a570 100644
> --- a/include/linux/leds.h
> +++ b/include/linux/leds.h
> @@ -44,11 +44,21 @@ struct led_classdev {
> #define LED_BLINK_ONESHOT_STOP (1 << 18)
> #define LED_BLINK_INVERT (1 << 19)
> #define LED_SYSFS_DISABLE (1 << 20)
> +#define LED_DEV_CAP_TORCH (1 << 21)
>
> /* Set LED brightness level */
> /* Must not sleep, use a workqueue if needed */
> void (*brightness_set)(struct led_classdev *led_cdev,
> enum led_brightness brightness);
> + /*
> + * Set LED brightness immediately - it is required for flash led
> + * devices as they require setting torch brightness to have immediate
> + * effect. brightness_set op cannot be used for this purpose because
> + * the led drivers schedule a work queue task in it to allow for
> + * being called from led-triggers, i.e. from the timer irq context.
> + */
> + int (*torch_brightness_set)(struct led_classdev *led_cdev,
> + enum led_brightness brightness);
> /* Get LED brightness level */
> enum led_brightness (*brightness_get)(struct led_classdev *led_cdev);
>
> @@ -157,6 +167,17 @@ extern void led_set_brightness(struct led_classdev *led_cdev,
> extern int led_update_brightness(struct led_classdev *led_cdev);
>
> /**
> + * led_set_torch_brightness - set torch LED brightness
> + * @led_cdev: the LED to set
> + * @brightness: the brightness to set it to
> + *
> + * Returns: 0 on success or negative error value on failure
> + *
> + * Set a torch LED's brightness.
> + */
> +extern int led_set_torch_brightness(struct led_classdev *led_cdev,
> + enum led_brightness brightness);
> +/**
> * led_sysfs_disable - disable LED sysfs interface
> * @led_cdev: the LED to set
> *
> --
> 1.7.9.5
>
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