Diagnose and repair video (graphics card) driver issues

Last update on Oct. 6, 2013.

Diagnose and repair video (graphics card) driver issues

This guide will attempt to help you diagnose or repair your video (graphics card) driver issue.

This guide will not go into great detail but will give some basic pointers. It will also help you to get support from the Kwheezy support channels. If you need support, following this guide first will speed up the process.

We will consider two main categories of failure:

1.) Failure to boot into a graphical session. This graphical session that provides a login and then a graphical desktop is provided by a service called 'X'. Also commonly refered to as Xorg or "the X server". It manages graphics cards, monitors, keyboards, mouse and touchpads.

2.) Undesirable behaviour or lack of compositing (3D effects) within a graphical login (desktop session).

Section 1 - No graphics, only a black screen with a text based login prompt.

This happens when X fails to start properly, in fact it has probably crashes (gracefully or otherwise). The first thing to do is to find out what graphics card you have, or at least what the system detects. Login as root.

Diagnosing X errors:

Type the following command (from now on this implies hitting the enter key after typing the command):

 lspci | grep VGA

Like most things in the UNIX/Linux command line, it is case sensitive. you should get some output as such:

[email protected]:~# lspci | grep VGA
01:00.0 VGA compatible controller: NVIDIA Corporation Device 11c0 (rev a1)

This tells me I am using an Nvidia graphics card. And the other code (11c0) may tell us more information like the model or series. This is useful to post of support channels, it will help those helping you.

Next step is to find out why X is failing and what driver it's trying to use. Type following command:

cat /var/log/Xorg.0.log | egrep "EE|error|warning|river|"

You may get something like this (screenshot of output)

In my example the "intel: Driver ..." part of the output tells us it's trying to use the intel driver. Yet we know that our video card is Nvidia.

So, we can rectify this by using the command line tool "switch-video-driver". Enter this command:

switch-video-driver

The output should look as follows:

[email protected]:~# switch-video-driver
Usage: /usr/sbin/switch-video-driver [-h|--help] | [-i|--init] | video_driver

Supported drivers:
fbdev 
fglrx
intel
nouveau
nvidia
radeon
vesa
opensource
other

As you can see, it shows the supported drivers. "opensource" is a good safe bet. Also; "other" may be worth a try if you don't have a nvidia, ati/amd or intel card. "fbdev" may work in some rare cases. However, for my case; since I know I have nvidia I can use a relevant driver. both the "nouveau" (open source) and "nvidia" (proprietary) should work. Try both, and see which works better. If you have intel, "intel" is a safe bet. If you have ati/amd then the "radeon" (open source) or "fglrx" (proprietary) would be best.

So, let's say i want to go with "nvidia". type the following (as root):

switch-video-driver nvidia

Then reboot. Hopefully everything works better now. If not at least you have some information to give to the kind soul in the forums etc, that may help you.

Section 2 - Got to the graphical desktop, but it's glitchy or no compositing (3D effects / transparency)

So if you get to the desktop, then your driver is working. It may not be the most suitable driver, but it works. In this case, first try changing the KDE settings. 

  • Open from the launcher (bottom left)  -> Settings -> System Settings. Or, if you can't do that type Alt+F2 and enter "system settings", selecting the obvious option.
  • Then select Desktop Effects. Make sure that "Enable desktop effects at startup" is enabled. (click Apply)
  • Then select the Advanced tab. Ideally you want to use OpenGL (hardware, fast), but if that is causing problems, perhaps settle for XRender (software, slow).
  • If these still don't improve thins, try toggling "Use OpenGL shaders" and/or "Use vsync".

So, hopefully one of those has solved your problem. If not, the next thing to try is changing the video (graphics card) driver. Bear in mind that selecting the wrong video driver could result in losing your graphical boot altogether. I recommend you print out this guide before going further. Then you can use the instructions above to get back to a working driver.

To change the video driver:

  • Open it from the launcher -> System -> Kwheezy Switch Video Driver. (or use Alt+F2 and type switch video...)
  • You may need to enter the root password, if prompted for it.
  • Try using "recommended open source" then click Apply and reboot.
  • If this doesn't work any better, try again but using "recommended proprietary", likewise reboot to take effect.
  • Otherwise, if you know what driver you want to use, select it from the list.

That's all folks! If you still have issues, please use the Kwheezy support channels, or use the debian support channels.

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