Blank (disconnected) screen during boot with latest 2.6.35-rcX kernels

[trapDoor]

Dear kernel Developers,
I'd like to report a bug occurring on my machine with some of the
latest 2.6.35-rcX and the '-next' kernels. As I'm not sure what is the
problem related to I may have omitted relevant people among the
recipients. If it is so I'll be thankful if someone could cc them.
Also I must apologise for reporting this so late, when it's close to
the end of development cycle for 2.6.35.

I didn't try to bisect. I've never done it before and maybe someone
will able to reproduce the problem or see straight what's going on by
looking into attached log/config files. But if it is necessary I'll
try my hand at bisecting.

******
Description of the problem:

Affected kernels tested by me: 2.6.35-rc5-git3, 2.6.35-rc4-git5 and
2.6.35-rc4-next-20100712.
Kernel 2.6.34.1 works OK.

Briefly what happens is that my graphics card seems to loose
connection with the LCD screen (connected through DVI) during boot.
Initially it does show something - a blank screen with blinking cursor
but it lasts only for about 2-3 seconds and then the screen switches
to stand-by mode giving message 'No signal detected !'. The booting
process seems to continue though, and looking cursorily through
related dmesg and Xorg logs I can't see any suspicious messages
(comparing with the same logs produced when booting from working
kernel). I'm attaching the following files with this e-mail:
    dmesg, Xorg.0.log - produced during successful boot with 2.6.34.1
    dmesg.0, Xorg.0.log.old - these are for the failed boot with 2.6.35-rc5-git3

Also please find attached config files:
    config-2.6.34.1 - for my current, working kernel
    config-2.6.35-rc5-git3 - based on above, almost all new entries I
left undefined/disabled during making 'oldconfig'; particularly I
didn't touch any options related to PCI, graphics drivers, ACPI or
power management - these should be all the same as in config-2.6.34.1

All the kernels were compiled on the same PC and system, they have/had
radeon-kms enabled by default and these firmware files compiled in:
R600_rlc.bin, R700_rlc.bin

******
A brief specification of my system:

1) OS/software:

Ubuntu 10.04, amd64

Xorg, xserver, drm, mesa, drm and ati/radeon drivers installed from
the following Ubuntu PPA repository:
https://edge.launchpad.net/~xorg-edgers/+archive/ppa/

Current versions:
xorg:  1:7.5+6ubuntu1~xorgedgers3~lucid
xserver:  2:1.8.2+git20100705+server-1.8-branch.665aa7ce-0ubuntu0sarvatt2~lucid
xserver-xorg-video-ati:  1:6.13.99+git20100716.cdeb1949-0ubuntu0sarvatt~lucid
xserver-xorg-video-radeon:  1:6.13.99+git20100716.cdeb1949-0ubuntu0sarvatt~lucid
drm:  1:2.4.20+git20100513.a3305b07-0ubuntu0sarvatt~lucid
mesa:  7.9.0+git20100718.4eaf591d-0ubuntu0sarvatt~lucid

2) Hardvare:
MB: Asus M4A79T Deluxe with chipsets AMD 790FX/SB750
Processor: AMD Phenom II X4 810
Graphics Card: Asus EAH3650 SILENT/HTDI/512M - based on chipset RV635
PRO, port PCIEx2, connected with LCD through DVI

******
Please let me know if anyone requires additional details and if there
is any tracking/testing I could do on my end.

--
Regards
trapDoor
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