Very strange video output problem with SM501 graphics card
Submitted by Laércio de Sousa
Assigned to Xorg Project Team
Created attachment 100837 Very strange error on SM501 graphics card
I have a multiseat computer consisting of an onboard Intel series 4 video chip and an external Silicon Motion SM501 PCI graphics card.
I also have a dual-boot Linux install, with a legacy Ubuntu 10.04 LTS with Userful Multiseat and a modern systemd-based Linux Distro (Fedora 20, openSUSE 13.1, Ubuntu 14.04 LTS, etc.).
When I boot the modern distro for the very first time, I got a strange error in the SM501 video output, as you can see in the attached image. Nevertheless, I can access that display normally via VNC.
If I reboot my computer in Ubuntu 10.04 + Userful Multiseat, then SM501 video output goes back to normal. After that, I can reboot my system safely to the modern distro, without getting that problem again. However, if I turn the computer off, and then turn it on again, the problem returns.
NOTE: Modern distro uses xorg-server-1.15 and xf86-video-siliconmotion-1.7.7 open source driver. Ubuntu 10.04 uses Userful proprietary X server based on modified xorg-server 1.5.3, with proprietary siliconmotion driver.
I have absolutely no idea of where to begin debugging siliconmotion driver.