Re: RGB LED class Re: [PATCH v2 2/2] leds: lp50xx: Add the LP50XX family of the RGB LED driver
From: Pavel Machek
Date: Mon Jan 28 2019 - 18:04:14 EST
Hi!
> >>What algorithm would be used for mapping brightness levels to RGB values
> >>in case of devices without hardware support for that?
> >
> >Output power = brightness / max_brightness * pwm_channel[x].
>
> IIUC you mean it as a formula for calculating r,g,b, values?
> I.e., on brightness setting we would have to do this calculation for
> each of three channels?
>
> Then, it will result in changing hue as well. That's why we're
> discussing HSV.
It should not change the hue, AFAICT, modulo the rounding errors.
> >>s/pwm/color/
> >
> >s/pwm/power/ would work for me.
>
> Power implies physical units. I'd prefer "intensity".
Intensity would work for me, too.
> >>Besides white also other color presets could be defined in DT.
> >
> >They should not be neccessary. When userspace knows what is white and
> >that power is linear with values in power_channels, it should be able
> >to do colorspace conversion itself.
>
> Have you verified it in practice? Would it allow to convert RGB values
> of the color displayed on the monitor to LED RGB class intensities,
> allowing to achieve similar color on the LED?
Yes, I think so.
My code is in unicsy_demo repository, in monitor/notint.py .
Pavel
--
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