[PATCH v2 09/11] Documentation: leds: Add description of v4l2-flash sub-device

[Jacek Anaszewski <j.anaszewski-Sze3O3UU22JBDgjK7y7TUQ@public.gmane.org>]

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

Signed-off-by: Jacek Anaszewski <j.anaszewski-Sze3O3UU22JBDgjK7y7TUQ@public.gmane.org>
Acked-by: Kyungmin Park <kyungmin.park-Sze3O3UU22JBDgjK7y7TUQ@public.gmane.org>
Acked-by: Sakari Ailus <sakari.ailus-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>
Cc: Bryan Wu <cooloney-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
Cc: Richard Purdie <rpurdie-Fm38FmjxZ/leoWH0uzbU5w@public.gmane.org>
---
 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 19bb673..8623413 100644
--- a/Documentation/leds/leds-class-flash.txt
+++ b/Documentation/leds/leds-class-flash.txt
@@ -20,3 +20,16 @@ Following sysfs attributes are exposed for controlling flash LED devices:
 	- max_flash_timeout
 	- flash_strobe
 	- flash_fault
+
+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

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