Sunsetting PowerDevil's XRandrBrightness

[Bhushan Shah]

Hi Kai,

On Wed, May 20, 2020 at 09:31:07PM +0200, Kai Uwe Broulik wrote:
> XRandR is doing X calls and we have some lovely animated screen brightness
> change. However, the UPower "backend" in PowerDevil is quite a spaghetti
> class and having multiple ways to control LEDs doesn't help.

I have one patchset work in progress to make upowerbackend not backend
anymore, I will post that up for review later this week I think.

> Can we get rid of the XRandrBrightness class and just use sysfs in every
> case?

You know what I will say! :D

But, yes +1000!

> XRandR Brightness doesn't work on Wayland, obviously, and the Intel
> driver which supported it is dead. Are there any other GPU drivers or models
> that use XRandR over sysfs? AMD, nvidia? I vaguely recall something but I
> don't know for sure.

Can we figure out some stats from e.g. bug reports and logs we have
available?

One thing which this will trip over is, if device supports both XRandr
and normal backlight control, then code will prefer to still use the
XRandr, so not sure if we can "trust" data.

You'd need something like this to short-circuit the XRandR backend and
verify that it still works with sysfs interface.

https://invent.kde.org/plasma/powerdevil/snippets/935

> (We're super early in the 5.20 cycle, so if we rip it out now, we still have
> four months to ignore any requests to put it back in ;)

I agree with this.

-- 
Bhushan Shah
http://blog.bshah.in
IRC Nick : bshah on Freenode
GPG key fingerprint : 0AAC 775B B643 7A8D 9AF7 A3AC FE07 8411 7FBC E11D
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