"DVI-0 Disconnceted" with DVI-to-VGA on analog CRT

[Coadey]

A Radeon X1550 (RV505) with one DVI port works great with a VGA 
multisync CRT and DVI-to-VGA adapter. Custom modelines, vsync and direct 
render are perfect, with xrandr reporting "DVI-0 connected".

However with a different monitor (an analog arcade CRT), xrandr reports 
"DVI-0 disconnected" and lists only a single defined mode, which does 
display properly. I've tried several different cables and DVI-to-VGA 
adapters.

I'm confident the problem is software, as it worked under the last 
radeon driver I used (most likely current git in early March).  I'm now 
on Debian Sid, 2.6.30-1-686-bigmem, and up-to yesterdays git of 
xf86-video-ati (2009-07-24).

xrandr --verbose:   http://pastebin.com/f2d18e989
xorg.conf:   http://pastebin.com/f1ed6090a
Xorg.0.log:   http://pastebin.com/f180397bd
lspci -v:   http://pastebin.com/f77fe0021
dmesg:   http://pastebin.com/f53a7facf
dpkg -l:   http://pastebin.com/m7b7f4fca

Besides xorg.conf changes, I've tried "nomodeset" under the kernel, and

xrandr --output DVI-0 --set load_detection 0
xrandr --output DVI-0 --set dvi_monitor_type analog

(Both produce: X Error of failed request: BadMatch (invalid parameter 
attributes)).

It seems similar to the following problem, yet I am using the latest 
ati/radeon git:

http://lists.freedesktop.org/archives/xorg/2009-March/044571.html

Whenever "xrandr -q" is called in this scenario, this is printed to 
Xorg.0.log:

(II) RADEON(0): Output: DVI-0, Detected Monitor Type: 0
Dac detection success
Unhandled monitor type 0
(II) RADEON(0): EDID for output DVI-0

I can manually add modes with "xrandr --newmode " and then "xrandr 
--addmode", however the modes can't actually be used (the video signal 
has no sync, and this error is displayed):

(EE) RADEON(0): No encoder assigned to output!

Can anyone please tell me how the xserver can correctly report (e.g. to 
xrandr) that a display is connected (and therefore use the rest of the 
xorg.conf modelines)?  Is this a bug in xorg?

Again this all works simply by physically changing to a different CRT 
monitor on the same DVI-to-VGA adapter, or by reverting to an older (3 
months or so) radeon driver.

Thanks!