Bug 232296 – distorted video on xf86-video-mga with kernel >2.6.22

• Status: RESOLVED FIXED
• Product: Gentoo Linux

[Description Daniel 2008-07-19 07:20:53 UTC]

I have a messy display since a Linux kernel upgrade (to 2.6.23, or 24, or 25). The screen (CRT) is wiggly, distorted and flickery; like shaking vertically. Nothing else than the kernel was updated.

VertRefresh is always lower than specified, sometimes monitor switches off because of illegal (low) VertRefresh rates.

The distortion is related to CPU usage (i.e. under higher CPU load, it gets better).

Everything is perfectly OK if I boot into kernel 2.6.22.

already tried: disable all xorg modules, changing all screen parameters, manually create modelines, use vanilla kernel, unstable xorg, even git.freedesktop.org sources. what else?

It's a Matrox G550, nForce2 AGP, xorg-server 1.3.0, xf86-video-mga 1.4.6.1. (also tested server 1.4.2 and mga 1.4.9). Nothing revealing in xorg.0.log.

Any hints highly appreciated! 

Cheers,
Daniel

Reproducible: Always

Steps to Reproduce:
upgrade Kernel to >= 2.6.22

[Comment 1 Daniel 2008-07-19 07:29:44 UTC]

Created attachment 160800 [details]
xorg.conf

[Comment 2 Daniel 2008-07-19 07:30:40 UTC]

Created attachment 160801 [details]
emerge --info

[Comment 3 Daniel 2008-07-19 07:31:47 UTC]

Created attachment 160803 [details]
Xorg.0.log

[Comment 4 Daniel 2008-07-19 07:33:44 UTC]

Created attachment 160805 [details]
tuxonice-sources-2.6.24-r9 .config

[Comment 5 Donnie Berkholz (RETIRED) 2008-07-20 01:22:25 UTC]

Try turning off the matrox framebuffer stuff in your kernel and make sure you're using vesa instead.

[Comment 6 Daniel 2008-07-20 15:06:16 UTC]

Aw that really did it. That's amazing, thank you.

What's the difference to just disabling framebuffer at boot time?

It would be nice to have a decent matroxfb, though. How is it conflicting with X?

Cheers
Daniel