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Subject[PATCH/RFC 3/8] Documentation: leds: Add description of flash mode
Date
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.txt | 25 +++++++++++++++++++++++++
1 file changed, 25 insertions(+)

diff --git a/Documentation/leds/leds-class.txt b/Documentation/leds/leds-class.txt
index 62261c0..d34d990 100644
--- a/Documentation/leds/leds-class.txt
+++ b/Documentation/leds/leds-class.txt
@@ -8,6 +8,31 @@ LED is defined in max_brightness file. The brightness file will set the brightne
of the LED (taking a value 0-max_brightness). Most LEDs don't have hardware
brightness support so will just be turned on for non-zero brightness settings.

+Some LED devices support two modes - torch and flash. A LED subsystem device
+driver can declare this by calling led_classdev_init_flash function and
+initializing flash field of the led_classdev structure (see <linux/leds.h>).
+There are five sysfs attributes dedicated specifically to the flash LED devices:
+
+ - flash_mode - sets/unsets the flash mode
+ - flash_timeout - determines duration of the flash blink in milliseconds
+ - max_flash_timeout - maximum flash blink duration that can be set (RO)
+ - flash_fault - bitmask of flash faults that may have occured, possible
+ flags are:
+ * 0x01 - Flash controller voltage to the flash LED has exceeded
+ the limit specific to the flash controller.
+ * 0x02 - The flash strobe was still on when the timeout set by
+ the user has expired. Not all flash controllers may set
+ this in all such conditions.
+ * 0x04 - The flash controller has overheated.
+ * 0x08 - The short circuit protection of the flash controller
+ has been triggered.
+ * 0x10 - Current in the LED power supply has exceeded the limit
+ specific to the flash controller.
+ - hw_triggered - Some devices expose dedicated hardware pins for
+ triggering a flash LED. The attribute allows to set
+ this mode. After writting 1 the brightness has to be set
+ to the desired value to arm a led.
+
The class also introduces the optional concept of an LED trigger. A trigger
is a kernel based source of led events. Triggers can either be simple or
complex. A simple trigger isn't configurable and is designed to slot into
--
1.7.9.5


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