Comment 10 for bug 103945

This bug is also reported in Ubuntu here: https://bugs.launchpad.net/ubuntu/+source/xorg/+bug/103945

On 64-bit systems with ATI cards, Xorg recognizes the ati card but fails to find a suitable mode. This occurs whether the xorg.conf is present or not. The original reporter says he got it working by hand-editing modelines into xorg.conf.

In speaking with Alex Deucher, he adds:
<agd5f> vesa fails on my radeon on 64 bit
<agd5f> don't know why. even kernel vesafb fails

Original report:

"The feisty beta desktop cd for amd64 boots ok on my nc6400, but gdm fails to start. The error log suggests that xorg found the ati video card, but couldn't find a valid mode. If I remove /etc/X11/xorg.conf entirely, xorg still can't find a usable mode. If I hand-edit the xorg.conf to add some modelines, I can get 1024x768 to work.

Here are some details that may help:

$ lspci | grep ATI
01:00.0 VGA compatible controller: ATI Technologies Inc M52 [ATI Mobility Radeon X1300]
$ sudo ddcprobe
vbe: VESA 3.0 detected.
oem: ATI ATOMBIOS
vendor: (C) 1988-2005, ATI Technologies Inc.
product: M52T 01.00
memory: 16384kb
mode: 640x400x256
mode: 640x480x256
mode: 800x600x256
mode: 1024x768x256
mode: 1280x1024x256
mode: 640x480x32k
mode: 640x480x64k
mode: 640x480x16m
mode: 800x600x32k
mode: 800x600x64k
mode: 800x600x16m
mode: 1024x768x32k
mode: 1024x768x64k
mode: 1024x768x16m
mode: 1280x1024x32k
mode: 1280x1024x64k
mode: 1280x1024x16m
mode: 320x200x32k
mode: 320x200x64k
mode: 320x200x16m
mode: 1600x1200x256
mode: 1600x1200x32k
mode: 1600x1200x64k
edid:
edid: 1 3
id: 8d00
eisa: LPL8d00
serial: 00000000
manufacture: 0 2005
input: analog signal.
screensize: 30 19
gamma: 2.200000
dpms: RGB, no active off, no suspend, no standby
dtiming: 1280x800@59
monitorid: LGPhilipsLCD
monitorid: LP141WX1-TLA
$ sudo /usr/share/xresprobe/ddcprobe.sh
res: 1280x800
disptype: crt
name:
freq:

The ddcinfo seems off: this is definitely an lcd, not a crt. The input is digital, I'd think, and the dpms is probably wrong too. The native lcd resolution, 1280x800, isn't listed in the modes.

If I can provide any other info, please let me know."