"DVI-0 Disconnceted" with DVI-to-VGA on analog CRT [Bug Found]

[Coadey]

Alex Deucher wrote:
> On Sat, Jul 25, 2009 at 3:05 PM, Coadey<coadey at gmail.com> wrote:
>   
>> 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?
>>     
>
> Load detection is enabled by default on the avivo cards so there's no
> need to force it on.
> If the driver is not able to detect anything attached (either via edid
> or load detection) it falls back to enabling a default output.
> Nothing is reported as connected because nothing is actually detected
> as attached.  You can force it to be enabled via your xorg.conf.  Add:
> Option "Enable" "true"
> to your monitor section.  see this page for more info:
> http://wiki.debian.org/XStrikeForce/HowToRandR12
>
>   
>> 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.
>>     
>
> Can you use git bisect to find out what commit broke it?
>
> Alex
>   
OK the bug was introduced by the following commit.  However on revisions 
prior to this, a different bug existed;  "xrandr -q" would toggle 
between showing "DVI-0 connected" and "DVI-0 disconnected" every time it 
was called.  Guess it's time for me to file a bug report?:

6ae54d3ea023968887bf0cb0ec1be2115621d554 is first bad commit
commit 6ae54d3ea023968887bf0cb0ec1be2115621d554
Author: Alex Deucher <alexdeucher at gmail.com>
Date:   Wed Mar 18 11:50:22 2009 -0400

    AVIVO: Fix dac load detection

:040000 040000 562616a69c3bddb67e77d9e8484857e1833b06fa 
48df781751de5a6288f28cd7afce952403f358cd M    src