Am 01.03.2016 um 10:25 schrieb Jacek Anaszewski: > On 02/29/2016 09:25 PM, Heiner Kallweit wrote: >> Am 29.02.2016 um 17:14 schrieb Jacek Anaszewski: >>> On 02/25/2016 11:13 PM, Heiner Kallweit wrote: >>>> Document the color extension in Documentation/leds/leds-class.txt >>>> >>>> Signed-off-by: Heiner Kallweit <hkallweit1@xxxxxxxxx> >>>> --- >>>> 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><HHHHHHHH><SSSSSSSS><VVVVVVVV> >>>> +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. >>> >>> I was thinking especially about highlighting the use case when we set >>> different hue and sat for different LEDs that are registered on some >>> trigger, and a driver that is currently unaware of LED RGB extension can >>> set only brightness and the LEDs will react with changing their >>> colors but each of them in different manner, according to the hue >>> and sat set. >>> >> I have to admit that I have a hard time trying to understand what you mean. > > I was writing this in a hurry - sorry about that. > >> With >> "a driver that is currently unaware of LED RGB extension can set only brightness" >> you mean a driver calling led_trigger_event? >> Arguments to led_trigger_event are always <= LED_FULL what means that the (potential) >> color of all LEDs attached to the trigger isn't touched. > > Changing brightness in HSV model influences resultant color, doesn't it? > Not in general, see led_rgb_adjust_hue_sat(). If brightness <= LED_FULL then hue and sat aren't touched. Only the value component is changed. >>>> 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 >>>> >>> >>> >> >> >> > > -- To unsubscribe from this list: send the line "unsubscribe linux-leds" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
