3 files changed, 81 insertions, 3 deletions
diff --git a/Documentation/leds/leds-class-flash.txt b/Documentation/leds/leds-class-flash.txt
index 19bb67355424..8da3c6f4b60b 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.
diff --git a/Documentation/leds/leds-class.txt b/Documentation/leds/leds-class.txt
index 79699c200766..62261c04060a 100644
--- a/Documentation/leds/leds-class.txt
+++ b/Documentation/leds/leds-class.txt
@@ -2,9 +2,6 @@
 LED handling under Linux
 ========================
 
-If you're reading this and thinking about keyboard leds, these are
-handled by the input subsystem and the led class is *not* needed.
-
 In its simplest form, the LED class just allows control of LEDs from
 userspace. LEDs appear in /sys/class/leds/. The maximum brightness of the
 LED is defined in max_brightness file. The brightness file will set the brightness
diff --git a/Documentation/leds/leds-lp5523.txt b/Documentation/leds/leds-lp5523.txt
index 5b3e91d4ac59..0dbbd279c9b9 100644
--- a/Documentation/leds/leds-lp5523.txt
+++ b/Documentation/leds/leds-lp5523.txt
@@ -49,6 +49,36 @@ There are two ways to run LED patterns.
 2) Firmware interface - LP55xx common interface
   For the details, please refer to 'firmware' section in leds-lp55xx.txt
 
+LP5523 has three master faders. If a channel is mapped to one of
+the master faders, its output is dimmed based on the value of the master
+fader.
+
+For example,
+
+  echo "123000123" > master_fader_leds
+
+creates the following channel-fader mappings:
+
+  channel 0,6 to master_fader1
+  channel 1,7 to master_fader2
+  channel 2,8 to master_fader3
+
+Then, to have 25% of the original output on channel 0,6:
+
+  echo 64 > master_fader1
+
+To have 0% of the original output (i.e. no output) channel 1,7:
+
+  echo 0 > master_fader2
+
+To have 100% of the original output (i.e. no dimming) on channel 2,8:
+
+  echo 255 > master_fader3
+
+To clear all master fader controls:
+
+  echo "000000000" > master_fader_leds
+
 Selftest uses always the current from the platform data.
 
 Each channel contains led current settings.