[gentoo-user] Madly flickering display

[Peter Humphrey <peter@prh.myzen.co.uk>]

I've broken this out from the thread it appeared in, Problems with Xinerama 
after upgrade to Plasma (KDE5):

On Friday 16 Sep 2016 11:18:18 I wrote:

--->8

> I upgraded yesterday from 5.7.4 to 5.7.5. I hoped the problem I have had
> been fixed, but no. If I switch desktops too many times, or too often or
> something, the desktop becomes unusable until I reboot (I haven't tried
> just restarting xdm). It flickers rapidly, bits of one desktop are shown
> in the middle of another or on a blank background, and it's hard to see
> just which is the currently active desktop.
> 
> This may be a bad interaction with the xorg-driver for my AMD GPU, which
> has only been on the market for about a year. Though
> sys-firmware/amdgpu-ucode hasn't changed since June.

I found from Xorg.0.log that X11 wasn't finding an evdev module, even though 
I had INPUT_DEVICES="evdev" in make.conf. So I added USE=evdev to dev-
qt/qtgui* and that created the module, even though kensington@gentoo said it 
had nothing to do with it.

I still get the rapid flickering and general confusion though, which is 
cured by logging out and in again.

* That was the only relevant package to have such a USE flag, according to 
"equery h -p evdev".

-- 
Rgds
Peter