640x480 resolution with radeon and KMS
 

hi everybody,

i hope i'm posting this in the right place.

i have on old Thinkpad T42 with the Mobility Radeon 7500 graphics chip. it used to work like a charm with the open source radeon driver, until KMS came along. it had no problems except for fullscreen being always black. i thought this is because i have an old card, and used 'nomodeset' in the kernel line, which strangely cranked up the memory usage and made the system choppier, but i managed.

today i was testing the use of an external monitor at home, and found out not only that it only works properly with KMS enabled, but fullscreen games work like a charm (e.g. DOSBox, which i use a lot).

after experimenting a bit, i found out that on the internal display (LCD), 640x480 produces a black screen, while others work as expected. so i set dosbox to use 800x600 as the fullscreen resolution, and it works. :)

the problem is that there are a lot of games (and apps) that i use which provide no configuration options to set the resolution, so i end up with a black screen (when i'm using the internal display, of course).

bottom line: i'm not asking for anyone to fix my problems from a distance, basically blindfolded, i'm much rather looking for people who might have had a similar experience and found a way around the problem.

thanks,
bamdad

almost forgot, i'm using Fedora 13 with kernel version 2.6.33.8-149 and Xorg version 1.8.2.

i have a custom xorg.conf (which is needed even with KMS enabled, and yes, i've already tried, the problem is the same without it), i've uploaded it to pastebin for reference: http://pastebin.ca/1925282

thanks again,
bamdad

So with nomodeset, 640x480 works fine?

Adam

yes it does. but using an external display doesn't, and the system is also choppier. and on a laptop this old, you're happy with every bit of additional performance you can squeeze out..

by the way, i've noticed that if i boot with the external monitor attached, plymouth shows the graphical boot screen, but if it's unplugged, it only shows the text bar at the bottom.. weird..

Well that definitely sounds like a bug to me. Probably work checking an updated version of the kernel for a newer DRM, and an updated version of xf86-video-ati. If you still have problems, I'd report the issue on the freedesktop bug tracker.

Adam

i've already done that using Arch as a testing vehicle (it has the latest packages AFAIK). sadly, things only get worse.. SDL is broken (white screen), and even OpenGL is unbearably laggy. that's why i didn't report this as a bug. the later versions appear to be abandoning the M7 chipset completely, and filing a bug for an outdated release is not a good practice..

i'll stick with Fedora 13 now, as i'll be forced to replace this machine eventually.

my best bet is to try to somehow 'disable' the 640x480 resolution, and hope that programmes needing it will end up using the lowest screen resolution available to them. do you think there's a way to do that?

You could use the --delmode option for xrandr to remove a specific mode from that monitor. Not 100% sure it will work :-)

Adam

thanks. :) i'll look into it. i'm marking the thread as solved, it might help someone out.