On Thu, Apr 30, 2015 at 3:34 AM, Jacek Anaszewski
wrote:
> This patch extends LED Flash class documention by
> the description of interactions with v4l2-flash sub-device.
>
Thanks, applied
-Bryan
> Signed-off-by: Jacek Anaszewski
> Acked-by: Kyungmin Park
> Acked-by: Sakari Ailus
> Cc: Bryan Wu
> Cc: Richard Purdie
> ---
> Documentation/leds/leds-class-flash.txt | 47
> +++
> 1 file changed, 47 insertions(+)
>
> diff --git a/Documentation/leds/leds-class-flash.txt
> b/Documentation/leds/leds-class-flash.txt
> index 19bb673..4cedc58 100644
> --- a/Documentation/leds/leds-class-flash.txt
> +++ b/Documentation/leds/leds-class-flash.txt
> @@ -20,3 +20,50 @@ Following sysfs attributes are exposed for controlling
> flash LED devices:
> - max_flash_timeout
> - flash_strobe
> - flash_fault
> +
> +
> +V4L2 flash wrapper for flash LEDs
> +=
> +
> +A LED subsystem driver can be controlled also from the level of
> VideoForLinux2
> +subsystem. In order to enable this CONFIG_V4L2_FLASH_LED_CLASS symbol has to
> +be defined in the kernel config.
> +
> +The driver must call the v4l2_flash_init function to get registered in the
> +V4L2 subsystem. The function takes three arguments:
> +- fled_cdev : the LED Flash class device to wrap
> +- ops : V4L2 specific ops
> + * external_strobe_set - defines the source of the flash LED strobe -
> + V4L2_CID_FLASH_STROBE control or external source, typically
> + a sensor, which makes it possible to synchronise the flash
> + strobe start with exposure start,
> + * intensity_to_led_brightness and led_brightness_to_intensity -
> perform
> + enum led_brightness <-> V4L2 intensity conversion in a device
> + specific manner - they can be used for devices with non-linear
> + LED current scale.
> +- config : configuration for V4L2 Flash sub-device
> + * dev_name - the name of the media entity, unique in the system,
> + * flash_faults - bitmask of flash faults that the LED Flash class
> + device can report; corresponding LED_FAULT* bit definitions
> are
> + available in ,
> + * intensity - constraints for the LED in the TORCH or INDICATOR mode,
> + in microamperes,
> + * has_external_strobe - determines whether the flash strobe source
> + can be switched to external,
> + * indicator_led - signifies that a led is of indicator type, which
> + implies that it can have only two V4L2 controls:
> + V4L2_CID_FLASH_INDICATOR_INTENSITY and V4L2_CID_FLASH_FAULT.
> +
> +On remove the v4l2_flash_release function has to be called, which takes one
> +argument - struct v4l2_flash pointer returned previously by v4l2_flash_init.
> +
> +Please refer to drivers/leds/leds-max77693.c for an exemplary usage of the
> +v4l2 flash wrapper.
> +
> +Once the V4L2 sub-device is registered by the driver which created the Media
> +controller device, the sub-device node acts just as a node of a native V4L2
> +flash API device would. The calls are simply routed to the LED flash API.
> +
> +Opening the V4L2 flash sub-device makes the LED subsystem sysfs interface
> +unavailable. The interface is re-enabled after the V4L2 flash sub-device
> +is closed.
> --
> 1.7.9.5
>
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