From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jacek Anaszewski Subject: [PATCH/RFC v11 03/20] Documentation: leds: Add description of LED Flash class extension Date: Wed, 18 Feb 2015 17:20:24 +0100 Message-ID: <1424276441-3969-4-git-send-email-j.anaszewski@samsung.com> References: <1424276441-3969-1-git-send-email-j.anaszewski@samsung.com> Return-path: In-reply-to: <1424276441-3969-1-git-send-email-j.anaszewski@samsung.com> Sender: linux-media-owner@vger.kernel.org To: linux-leds@vger.kernel.org, linux-media@vger.kernel.org, devicetree@vger.kernel.org Cc: kyungmin.park@samsung.com, pavel@ucw.cz, cooloney@gmail.com, rpurdie@rpsys.net, sakari.ailus@iki.fi, s.nawrocki@samsung.com, Jacek Anaszewski List-Id: devicetree@vger.kernel.org The documentation being added contains overall description of the LED Flash Class and the related sysfs attributes. Signed-off-by: Jacek Anaszewski Acked-by: Kyungmin Park Cc: Bryan Wu Cc: Richard Purdie --- Documentation/leds/leds-class-flash.txt | 32 +++++++++++++++++++++++++++++++ 1 file changed, 32 insertions(+) create mode 100644 Documentation/leds/leds-class-flash.txt diff --git a/Documentation/leds/leds-class-flash.txt b/Documentation/leds/leds-class-flash.txt new file mode 100644 index 0000000..ff03a66 --- /dev/null +++ b/Documentation/leds/leds-class-flash.txt @@ -0,0 +1,32 @@ + +Flash LED handling under Linux +============================== + +Some LED devices provide two modes - torch and flash. In the LED subsystem +those modes are supported by LED class (see Documentation/leds/leds-class.txt) +and LED Flash class respectively. The torch mode related features are enabled +by default and the flash ones only if a driver declares it by setting +LED_DEV_CAP_FLASH flag. + +In order to enable support for flash LEDs CONFIG_LEDS_CLASS_FLASH symbol +must be defined in the kernel config. A flash LED driver must register +in the LED subsystem with led_classdev_flash_register function to gain flash +related capabilities. + +There are flash LED devices which can control more than one LED and allow for +strobing the sub-LEDs synchronously. A LED will be strobed synchronously with +the one whose identifier is written to the flash_sync_strobe sysfs attribute. +The list of available sub-LED identifiers can be read from the available_sync_leds +sysfs attribute. In order to enable the related settings the driver must set +LED_DEV_CAP_SYNC_STROBE flag. + +Following sysfs attributes are exposed for controlling flash LED devices: +(see Documentation/ABI/testing/sysfs-class-led-flash) + - flash_brightness + - max_flash_brightness + - flash_timeout + - max_flash_timeout + - flash_strobe + - available_sync_leds + - flash_sync_strobe + - flash_fault -- 1.7.9.5