Hi Pavel,
On 19/01/2019 23.46, Pavel Machek wrote:
Hi!
Moreover, I think that RGB LED class with configurable
brightness-model, and with possible color range adjustments via
icc-profiles or something similar, is the best solution that has been
proposed so far. It is just flexible.
I'd like to capitalize on the ideas shared in this thread and have
finally LED RGB class materialized.
I have now updated my github code with my understanding of the discussion:
https://github.com/vesajaaskelainen/linux/tree/wip-multi-color-led
Commits:
- dt-bindings: leds: Introduce linux,default-brightness-model for all leds
https://github.com/vesajaaskelainen/linux/commit/4ffb21d644056686096226bbede7c8c78b0254c2
- drivers: leds: Add core support for multi color element LEDs
https://github.com/vesajaaskelainen/linux/commit/627f38bb78cebc694b8e6d735fb088c87925435d
- dt-bindings: leds: leds-pwm: Introduce multi color element leds support
https://github.com/vesajaaskelainen/linux/commit/ef6c5730d621e79ea0b02470caa83bc39439536a
- WIP: drivers: leds: leds-pwm: Add multi color element LED support.
https://github.com/vesajaaskelainen/linux/commit/0430a27823d9162926424b32c23be1c53eb9cbe2
First two commits are common and could be taken before I am happy with the
pwm led driver changes. This new conditional feature flag makes it a bit
harder. Of course one option would be to require it to be enabled.
Current set of concepts:
- brightness-model: hardware, onoff, linear
- could be extended in future with other modes like hsv if wanted
Would it be enough to tell userspace what is relation between values
it writes and output power?
Onoff is subset of linear, I guess. We already have max_brightness in
the API.
Btw. there is slight problem with led trigger framework which is kinda
visible with "onoff" vs "linear" settings.
If you configure color like:
echo onoff > brightness_model
echo 32 0 32 255 > color
You get not so bright pink color. And if you then enable blinking:
echo heartbeat > trigger
Then it blinks with not so bright pink color as expected.
However if you do it:
echo linear > brightness_model
echo 255 0 255 32 > color
You once again you get not so bright pink color. However when you enable
blinking:
echo heartbeat > trigger
Then it blinks with very bright pink color.
Reason I believe is because trigger uses either values 0 or 255 for
brightness when controlling. To fix the issue I believe trigger
mechanism should be adjusted to allowing one to control ON brightness level.
I would recommend fixing this trigger problem with future patches for it.
Thanks,
Vesa Jääskeläinen
