Luca
On 10/24/20 4:16 AM, Luca Weiss wrote:
Hi Alex,
On Samstag, 24. Oktober 2020 08:42:38 CEST Alexander Dahl wrote:
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@lin
aro.org/>
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.
Exactly, that I understand well.
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?
That's from the i read from the documentation as well.
How is user space supposed to get function and/or color from the led? I don't
see it exposed in user space - apart from the directory name (label) in the
leds-gpio example.
This is what I get in sysfs for the multicolor led with the lpg driver:
brightness
device -> ../../../fc4cf000.spmi:pm8941@1:lpg
max_brightness
multi_index
If you refer to the ABI doc you see that by reading the multi_index file
gives you the colors contained within the file.
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/ABI/testing/sysfs-class-led-multicolor
Dan
