From mboxrd@z Thu Jan 1 00:00:00 1970 From: Heiner Kallweit Subject: [PATCH v4 3/4] leds: core: add documentation for color extension Date: Thu, 25 Feb 2016 23:13:25 +0100 Message-ID: <56CF7C85.7030005@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Return-path: Received: from mail-wm0-f66.google.com ([74.125.82.66]:34022 "EHLO mail-wm0-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751503AbcBYWRf (ORCPT ); Thu, 25 Feb 2016 17:17:35 -0500 Received: by mail-wm0-f66.google.com with SMTP id b205so6027326wmb.1 for ; Thu, 25 Feb 2016 14:17:34 -0800 (PST) Sender: linux-leds-owner@vger.kernel.org List-Id: linux-leds@vger.kernel.org To: Jacek Anaszewski Cc: linux-leds@vger.kernel.org Document the color extension in Documentation/leds/leds-class.txt Signed-off-by: Heiner Kallweit --- v2: - introduced to patch series v3: - document extension in more detail v4: - Better explain why flag LED_SET_HUE_SAT is needed --- Documentation/leds/leds-class.txt | 27 ++++++++++++++++++++++----- 1 file changed, 22 insertions(+), 5 deletions(-) diff --git a/Documentation/leds/leds-class.txt b/Documentation/leds/leds-class.txt index d406d98..b1e4cba 100644 --- a/Documentation/leds/leds-class.txt +++ b/Documentation/leds/leds-class.txt @@ -8,6 +8,22 @@ 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. +If a driver uses the colour extension of the LED core then the brightness +file can be used to set hue / saturation / value. The brightness value is +interpreted as: <0000000F> +Usage of the least byte is identical to monochrome mode. Saturation can be +0-255 and hue 0-251 (Colour circle is mapped to 0-252). +If hue and saturation both are 0 the current colour is preserved and only +the brightness is set. This ensures backwards compatibility with monochrome +mode, e.g. for led_set_brightness() calls from triggers. +However we might want to have the option to set all HSV components, even +if hue and saturation both are 0 (e.g. via brightness sysfs attribute). +Use case: Set color to white (hue = 0 and saturation = 0). +Therefore the default behaviour can be overridden with flag F (LED_SET_HUE_SAT). +If this flag is set then hue and saturation are not checked for being 0 and +the color components are set unconditionally. Example: +0x010000ff sets the LED to white color with full brightness. + 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 @@ -45,11 +61,12 @@ Is currently of the form: "devicename:colour:function" -There have been calls for LED properties such as colour to be exported as -individual led class attributes. As a solution which doesn't incur as much -overhead, I suggest these become part of the device name. The naming scheme -above leaves scope for further attributes should they be needed. If sections -of the name don't apply, just leave that section blank. +If the colour extension is used hsv / rgb can be used instead of a specific +colour. There have been calls for LED properties such as colour to be +exported as individual led class attributes. As a solution which doesn't +incur as much overhead, I suggest these become part of the device name. +The naming scheme above leaves scope for further attributes should they be +needed. If sections of the name don't apply, just leave that section blank. Brightness setting API -- 2.7.1