Lenovo T61 laptop experience

I got a good deal on a new Lenovo T61 from the Lenovo outlet store because Lenovo changed models. I was not interested in the newer laptops because they feature the ATI video cards, rather than the Nvidia. I've avoided ATI for years because I had trouble with them and generally I was able to make the Nvidia work with the proprietary drivers.

Ubuntu 8.10 installed cleanly and almost everything worked with no trouble. Sound is fine. The wireless is Intel iwl4965 and it works very very well, much better than the iwl3945 in my Dell Latitude D820. The FN key combinations all work--suspend, network on/off. screen light, and so forth. The LCD display is WSXGA+, capable of 1680x1050, and the Nvidia proprietary drivers version 177 delivers it just fine. To my eye, that resolution is a bit "squished" and I prefer 1400x1050, and had some trouble getting that display. It turned out that the LCD display returns an incorrect EDID frequency to the video card and so some resolutions in linux seem impossible, although one can boot into MS Windows and see that they really do work. I could not get any vertical and horizontal frequency information from Lenovo for the lcd, so I had to guess with some settings in xorg.conf. Eventually it did work at 1400x1050.

But I've had trouble running some programs. I use compiz as the window manager/compositor because I like to have different wallpapers on different workspaces. Some programs that display text on the screen simply don't "show" all text. I posted a couple of examples of mlterm where you can see black spots where the cursor or some file lists should be:


The blank spaces are filled in if you hit the return key a few times, but it can be very inconvenient if you are paging through output with "less" and the --less-- prompt is invisible at the bottom of the terminal. I use mlterm because it displays all international characters and it allows me to set a background image from the command line. I have lots of background images and randomly choose them for terminals. I used to use Eterm, but it is still not quite ready to display international characters. I spent almost a whole day compiling/ installing every terminal program I could find, never found a good substitute.

Then I saw another malfunction in the display of LyX, my favorite LaTeX document processor. I would type in lines and then move the cursor, and lines would be "drawn over" each other. That made me think i did not have an mlterm problem, but rather a display problem. That led me to suspect the nvidia NVS140M video card was troubled, and I started googling a lot. I did know know any magic words to search for, and I've not found anybody who describes the exact same problem. But there are people in the Nvidia linux forum who describe problems in Open Office.

One frustrating problem is that no two Nvidia cards seem to display exactly the same trouble. Some users describe problems like whole terminals appear all black or that the display is corrupted by lots of small geometric shapes. Nvidia has umpteen different card models placed in countless different motherboards with various displays. I found a lot of different fixups proposed, ranging from bits to add into xorg.conf or kernel options. For me, none of the xorg.conf changes helped. I learned that many of these don't apply on Ubuntu 8.10 because we are using the newer Xorg framework and a lot of the advice you get for other linux systems is just outdated.

To make the rest of the long story shorter, it turns out this is the fix for the T61. An option for the nvidia kernel module can be used to force the card's PowerMizer feature to stop slowing down the display. If this is not used, then the PowerMizer forces performance setting to 0, which is so slow that the terminal does not completely refresh itself. If you force the performance level to 2, the display is fine. Here's what I have in the module settings:

$ cat /etc/modprobe.d/nvidia
options nvidia NVreg_RegistryDwords="PerfLevelSrc=0x2222"
options nvidia NVreg_Mobile=1

This uses more power; battery life is shorter by about 30minutes. But everything displays properly.

There is a lot of arguing about whose fault this is. It does not appear to happen if one uses Metacity in Gnome, it is inflicted only on people who aim for accelerated 2d/3d effects. Some gamers describe this, but it mostly appears when one uses compiz or, as far as I can tell, the KDE4 compositing window manager that is based on compiz code. Some people allege that the combination of Compiz and Nvidia exposes a flaw in X11 that can be fixed, eventually. Others in the Nvidia list blame Nvidia for keeping their code closed. Others blame Compiz for, well, trying to use all the cool tools. If I had a clear idea of how this can be truly fixed, I'd file a bug report. But I expect the people who know how to fix this already know about it and they are doing what they can to fix it.

About pauljohn

Paul E. Johnson is a Professor of Political Science at the University of Kansas. He is an avid Linux User, an adequate system administrator and C programmer, and humility is one of his greatest strengths.
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