linux-kernel - [PATCH/RFC v9 15/19] Documentation: leds: Add description of v4l2-flash sub-device

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Message-id: <1417622814-10845-16-git-send-email-j.anaszewski@samsung.com>
Date:	Wed, 03 Dec 2014 17:06:50 +0100
From:	Jacek Anaszewski <j.anaszewski@...sung.com>
To:	linux-leds@...r.kernel.org, linux-media@...r.kernel.org,
	linux-kernel@...r.kernel.org
Cc:	kyungmin.park@...sung.com, b.zolnierkie@...sung.com, pavel@....cz,
	cooloney@...il.com, rpurdie@...ys.net, sakari.ailus@....fi,
	s.nawrocki@...sung.com, robh+dt@...nel.org, pawel.moll@....com,
	mark.rutland@....com, ijc+devicetree@...lion.org.uk,
	galak@...eaurora.org, Jacek Anaszewski <j.anaszewski@...sung.com>
Subject: [PATCH/RFC v9 15/19] 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@...sung.com>
Acked-by: Kyungmin Park <kyungmin.park@...sung.com>
Acked-by: Sakari Ailus <sakari.ailus@...ux.intel.com>
Cc: Bryan Wu <cooloney@...il.com>
Cc: Richard Purdie <rpurdie@...ys.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 82e58b1..bc3855b 100644
--- a/Documentation/leds/leds-class-flash.txt
+++ b/Documentation/leds/leds-class-flash.txt
@@ -48,3 +48,16 @@ Following sysfs attributes are exposed for controlling flash led devices:
 			  upper limit
 
 		Flash faults are cleared by reading the attribute.
+
+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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