Hello Luca, On Sat, Oct 24, 2020 at 12:48:42AM +0200, Luca Weiss wrote: > I'm currently experimenting with the qcom lpg[0] which is a driver for the rgb > notification led found on e.g. Snapdragon 801 devices (and many more), > specifically my example is about the Fairphone 2 (msm8974-fairphone-fp2). Great to hear someone is interested in mainline support for Fairphone. I just bought a used FP2 on ebay. :-) > > [0] https://lore.kernel.org/lkml/20201021201224.3430546-1-bjorn.andersson@xxxxxxxxxx/ > > My dts is looking like the following (abbreviated): > > [in lpg node] > multi-led { > color = <LED_COLOR_ID_MULTI>; > function = LED_FUNCTION_STATUS; > .... > }; > > I'm comparing this to the PinePhone where the leds are defined as follows: > > [in gpio-leds node] > blue { > function = LED_FUNCTION_INDICATOR; > color = <LED_COLOR_ID_BLUE>; > }; > > green { > function = LED_FUNCTION_INDICATOR; > color = <LED_COLOR_ID_GREEN>; > }; > > red { > function = LED_FUNCTION_INDICATOR; > color = <LED_COLOR_ID_RED>; > }; > > (sidenote: the LED_FUNCTION_INDICATOR should probably also be > LED_FUNCTION_STATUS there; the dts was made before the better descriptions for > the defines have been added) > > This gets the following directories created in /sys/class/leds/: > > blue:indicator > green:indicator > red:indicator That's right. From Linux point of view these behave like three independent LEDs. It's fully up to userspace to handle this. > > But with the multicolor led on the Fairphone 2 only a directory with the name > of "multi-led" gets created which I would have expected to be > "multicolor:status" instead. Obviously it's named after the node label. If I read Documentation/devicetree/bindings/leds/leds-class-multicolor.yaml correctly, that's how it is supposed to be named? > > > What's further confusing me is that include/dt-bindings/leds/common.h states > (reformatted for clarity): > > /* For multicolor LEDs */ > #define LED_COLOR_ID_MULTI 8 > > /* For multicolor LEDs that can do arbitrary color, so this would include RGBW > and similar */ > #define LED_COLOR_ID_RGB 9 > > It sounds like these comments are the wrong way around as it says that RGB > does RGBW & others while MULTI is normal RGB? > > I have also found this commit[1] while browsing through lkml which seems to > validate my suspicions that _ID_RGB should be used normally? This commit seems > have been applied early September but hasn't been merged in the 5.10 merge > window? > > [1] https://git.kernel.org/pub/scm/linux/kernel/git/pavel/linux-leds.git/ > commit/?h=for-next&id=3d93edc77515c6f51fa9bbbe2185e2ec32bad024 > > But drivers/leds/led-core.c also states "We want to label LEDs that can > produce full range of colors as RGB, not multicolor" - not sure what "full > range" means here. > > Thanks for reading through my long email and I'd appreciate any clarification > on the situation! I just read https://www.kernel.org/doc/html/latest/leds/leds-class-multicolor.html and apart from formatting and inter-doc-link issues due to not used markup features, I can understand how it's supposed to be used from userspace. However, multicolor is still quite new, maybe drivers/leds/TODO gives some hints? It seems to me some open issues are already known. ;-) HTH & Greets Alex -- /"\ ASCII RIBBON | »With the first link, the chain is forged. The first \ / CAMPAIGN | speech censured, the first thought forbidden, the X AGAINST | first freedom denied, chains us all irrevocably.« / \ HTML MAIL | (Jean-Luc Picard, quoting Judge Aaron Satie)
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