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. 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. >> 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
