Hi Karl, On 03/06/2016 09:55 PM, Karl Palsson wrote:
-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Heiner Kallweit <hkallweit1@xxxxxxxxx> wrote:Add generic support for RGB LED's. Basic idea is to use enum led_brightness also for the hue and saturation color components.This allows to implement the color extension w/o changes to struct led_classdev. Select LEDS_RGB to enable building drivers using the RGB extension. Flag LED_SET_HUE_SAT allows to specify that hue / saturation should be overridden even if the provided values are zero. Some examples for writing values to /sys/class/leds/<xx>/brightness: (now also hex notation can be used) 255 -> set full brightness and keep existing color if set 0 -> switch LED off but keep existing color so that it can be restored if the LED is switched on again later 0x1000000 -> switch LED off and set also hue and saturation to 0 0x00ffff -> set full brightness, full saturation and set hue to 0 (red)I admit I hadn't seen this earlier, and I didn't spend all day looking at previous attempts, but what's the motivation for putting all this overloaded syntax into the "brightness" file? I thought the point was to have a single value in each file, one of the references I did find was
With single value per file there would be problems with colour components setting synchronization.
http://www.spinics.net/lists/linux-leds/msg02995.html Is there some thread where this was decided as advantageous? Surely 0-255 for _brightness_ is what the brightness entry should do?
You can find a reference to the related discussion in [1].
I'd like to set the rgb colour of a led (or hsv, that can be it's own file too) and separately ramp the brightness up and down. I also think it's substantially simpler and easier to use from the user's point of view, which is surely the place you want easy right?
I'm also not very keen on overloading the brightness attribute semantics. Nonetheless it seems impossible to add support for setting three colour components otherwise than through a single syscall, if we want to make it synchronous and compatible with LED triggers. HSV color scheme is also very convenient for adapting monochrome brightness semantics to the RGB realm. [1] http://www.spinics.net/lists/linux-leds/msg05477.html -- Best regards, Jacek Anaszewski -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
