[Intel-gfx] Graphical Corruption on Series 4 Chipset using xf86-video-intel

[Benjamin Hodgetts]

Hello all,

I recently updated the graphics drivers on a large amount of office machines
and noticed that some of the machines are now showing graphical corruption
on icons and other parts of the XFCE4 interface (e.g. the clock or icons on
the panel) when you mouse over them (when the icon should raise slightly).
Moving the mouse back and forth over icons results in differing degrees of
corruption varying from very slight to completely destroyed. I doubt this is
specific to XFCE4, that's just the desktop environment that these machines
are using (and unfortunately I don't have any way of testing another).

The version we updated to was xf86-video-intel 1:2.99.917+552+ge41040f-1
(Arch Linux) although unfortunately I don't know what the old version we
were using was, but it was several months old.

The only machines experiencing corruption show under "lspci" as "Intel
Corporation 4 Series Chipset" as the VGA adapter. It's not all Intel GPU
machines as there are other machines with Intel onboard graphics which are
fine (either newer or older chipsets).

Switching to UXA rather than SNA fixes the graphical corruption, but this in
itself causes problems as it no-longer automatically uses the correct screen
resolution by default for monitors greater than 1280x1024 in multi-monitor
setups (e.g. monitor 1 will show 1600x900 just fine, monitor 2 despite being
a 1080p monitor will just show 1280x1024 for unknown reasons, this only
happens under UXA, not SNA). I'm not keen on switching back to UXA and
manually setting the monitor resolutions isn't viable as any machine may be
connected to any monitor at any time, so hard-coding it is a no-no.

TL;DR: Latest xf86-video-intel causes graphical corruption on "4 Series
Chipset" machines.

Thanks all.