[PATCH/RFC v8 03/14] Documentation: leds: Add description of v4l2-flash sub-device

Jacek Anaszewski
2014-11-28T09:26:07Z

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>
Cc: Bryan Wu <cooloney@gmail.com>
Cc: Richard Purdie <rpurdie@rpsys.net>
---
Documentation/leds/leds-class-flash.txt | 13 +++++++++++++
1 file changed, 13 insertions(+)

diff --git a/Documentation/leds/leds-class-flash.txt b/Documentation/leds/leds-class-flash.txt
index d68565c..1a611ec 100644
--- a/Documentation/leds/leds-class-flash.txt
+++ b/Documentation/leds/leds-class-flash.txt
@@ -46,3 +46,16 @@ Following sysfs attributes are exposed for controlling flash led devices:
until this flag is no longer set
* 0x100 - the temperature of the LED has exceeded its allowed
upper limit
+
+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. On remove the
+v4l2_flash_release function has to be called (see <media/v4l2-flash.h>).
+
+After proper initialization a V4L2 Flash sub-device is created. The sub-device
+exposes a number of V4L2 controls, which allow for controlling a LED Flash class
+device with use of its internal kernel 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