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

Signed-off-by: Jacek Anaszewski <j.anaszew...@samsung.com>
Acked-by: Kyungmin Park <kyungmin.p...@samsung.com>
Acked-by: Sakari Ailus <sakari.ai...@linux.intel.com>
Cc: Bryan Wu <coolo...@gmail.com>
Cc: Richard Purdie <rpur...@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 ff03a66..dc46ae0 100644
--- a/Documentation/leds/leds-class-flash.txt
+++ b/Documentation/leds/leds-class-flash.txt
@@ -30,3 +30,16 @@ Following sysfs attributes are exposed for controlling flash 
LED devices:
        - available_sync_leds
        - flash_sync_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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