[v7] Documentation: leds: Add description of v4l2-flash sub-device

  This patch extends LED Flash class documention by
the description of interactions with v4l2-flash sub-device.

Signed-off-by: Jacek Anaszewski <j.anaszewski@samsung.com>
Acked-by: Kyungmin Park <kyungmin.park@samsung.com>
Acked-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Cc: Bryan Wu <cooloney@gmail.com>
Cc: Richard Purdie <rpurdie@rpsys.net>
---
 Documentation/leds/leds-class-flash.txt |   47 +++++++++++++++++++++++++++++++
 1 file changed, 47 insertions(+)
  

On Thu, Apr 30, 2015 at 3:34 AM, Jacek Anaszewski
<j.anaszewski@samsung.com> 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 <j.anaszewski@samsung.com>
> Acked-by: Kyungmin Park <kyungmin.park@samsung.com>
> Acked-by: Sakari Ailus <sakari.ailus@linux.intel.com>
> Cc: Bryan Wu <cooloney@gmail.com>
> Cc: Richard Purdie <rpurdie@rpsys.net>
> ---
>  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 <linux/led-class-flash.h>,
> +       * 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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