Created attachment 16772 [details]
my Xorg configuration

I just had a first shot at the "nouveau" Xorg driver, I'm a regular
"nv" user. It compiled and installed without a itch in a short time,
congrats (great instructions on
http://nouveau.freedesktop.org/wiki/InstallNouveau), ran fine... but
with a funny vertical fencing effect: one vertical line out of two was
black. After a few minutes, the effect would spontaneously switch (no
input from me, no app activity) to white vertical lines with the same
stripping setup (which gives a "dimming" or "enlightening" effect +
rather crunchy text).

  When reverting to the "nv" driver and simply restarting X, the fencing
effect persisted. So "nv" seems to rely on some BIOS stuff that
"nouveau" fiddles with. I (warm-)rebooted the whole system with the
"nouveau" driver on in order for it to benefit from the BIOS, same
problem. Same procedure while adding the "Option FlatPanel True", same
problem. Then (warm-)reboot with the "nv" driver on, everything working
fine again.

  I have a NV34M on a Dell Inspiron laptop, all details follow (and both
nouveau and nv logs attached):

  - Linux vanilla 2.6.23.1 on i386
  - Xorg 1.4.1~git20080131-4 from Debian 'testing' branch (not
'unstable')
  - nv 2.1.9
  - nouveau (drm + xf86-video-nouveau) from git as 2008-05-23

01:00.0 VGA compatible controller: nVidia Corporation NV34M [GeForce FX
Go5200 64M] (rev a1)
        Subsystem: Dell Device 019c
        Flags: bus master, VGA palette snoop, 66MHz, medium devsel,
latency 32, IRQ 11
        Memory at fc000000 (32-bit, non-prefetchable) [size=16M]
        Memory at d0000000 (32-bit, prefetchable) [size=256M]
        Expansion ROM at fd000000 [disabled] [size=128K]
        Capabilities: <access denied>

  The screen is a 1920x1200 LCD (physical: 332x207mm, ~150dpi). I can't
provide screenshots as X obviously saw perfectly sane (non-fenced)
display buffers.

  What could I do to help you fix this bug ? It looks like I'm very
close to be able to switch to "nouveau".