Re: [PATCH v10 1/8] Documentation: leds: Add description of v4l2-flash sub-device

[Bryan Wu <cooloney@gmail.com>]

On Mon, Jun 8, 2015 at 2:02 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.
>

Merged into my -devel branch and it won't be merged into 4.2.0 merge
window but wait for one more cycle, since now it's quite late in 4.1.0
cycle.

Thanks,
-Bryan

> Signed-off-by: Jacek Anaszewski <j.anaszewski@samsung.com>
> Acked-by: Kyungmin Park <kyungmin.park@samsung.com>
> Cc: Richard Purdie <rpurdie@rpsys.net>
> ---
>  Documentation/leds/leds-class-flash.txt |   51 +++++++++++++++++++++++++++++++
>  1 file changed, 51 insertions(+)
>
> diff --git a/Documentation/leds/leds-class-flash.txt b/Documentation/leds/leds-class-flash.txt
> index 19bb673..8da3c6f 100644
> --- a/Documentation/leds/leds-class-flash.txt
> +++ b/Documentation/leds/leds-class-flash.txt
> @@ -20,3 +20,54 @@ 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 six arguments:
> +- dev       : flash device, e.g. an I2C device
> +- of_node   : of_node of the LED, may be NULL if the same as device's
> +- fled_cdev : LED flash class device to wrap
> +- iled_cdev : LED flash class device representing indicator LED associated with
> +             fled_cdev, may be NULL
> +- 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>,
> +       * torch_intensity - constraints for the LED in TORCH mode
> +               in microamperes,
> +       * indicator_intensity - constraints for the indicator LED
> +               in microamperes,
> +       * has_external_strobe - determines whether the flash strobe source
> +               can be switched to external,
> +
> +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.
> +This function can be safely called with NULL or error pointer argument.
> +
> +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
>