Two display anomalies (one still open)

[Matthew Saltzman]

On Thu, 8 Sep 2005, Bob Chiodini wrote:

> On Wed, 2005-09-07 at 20:16 -0400, Matthew Saltzman wrote:
>> If you are following this thread, there are updates on both issues below.
>>
>> Thanks for your suggestions so far.  Keep 'em coming!
>>
>> On Wed, 7 Sep 2005, Matthew Saltzman wrote:
>>
>>> On Wed, 7 Sep 2005, Bob Chiodini wrote:
>>>
>>>> On Tue, 2005-09-06 at 23:01 -0400, Matthew Saltzman wrote:
>>>>> On Tue, 6 Sep 2005, Bob Chiodini wrote:
>>>>>
>>>>>> On Tue, 2005-09-06 at 20:58 -0400, Matthew Saltzman wrote:
>> [...]
>>>
>>> That leaves this one:
>>>
>>>>>>>
>>>>>>> (2)
>>>>>>> Video card: ATI Radeon Mobility 7500 in an IBM Thinkpad T41.
>>>>>>> Driver: radeon
>>>>>>> Kernel: kernel-2.6.12-1.1398_FC4
>>>>>>> Kernel option: video=radeonfb
>>>>>>> X: xorg-x11-6.8.2-37.FC4.45
>>>>>>> Symptom: When I use the VGA-out jack to connect to an overhead projector
>>>>>>> or external monitor, the projector image ripples slowly, as though (very
>>>>>>> narrow) waves are passing over it.
>>>>>>>
>>>>>>> In FC3, this behavior varied with the kernel version.  In FC4, I need
>>>>>>> this
>>>>>>> kernel in order to get proper ACPI behavior, so I haven't tested much.
>>>>>>> In
>>>>>>> WinXP, the display is rock-solid.
>>>
>>> I'll check refresh rate in XP and Linux and test some cables and report back.
>>
>> Haven't tested yet, but I did find out that the vert. refresh rate in XP
>> is 60Hz.  It appears from the logs to also be 60Hz in X, but I changed
>> xorg.conf anyway.  That does not appear to affect the problem on my
>> externa monitor.  I will check the projector with a brand new cable
>> tomorrow.

Capping the vert refresh rate at 60Hz in xorg.conf had no effect.  In 
fact, it looks like 60Hz was the rate even before that change.

Brand new, high quality video cable had no effect.

Still stuck.  Audience still dizzy.

>>
>> Forgot to note that the problem occurs in a virtual console as well as in
>> X.
>>
>
> Matthew,
>
> The virtual terminal here is 720x400, 31.4 Khz horiz. and 70 Hz vert.  I
> would have expected 640x480 @ 60Hz.  Try lowering the resolution in X.
> That may not be ideal, but it may yield a clue.

I use the radeonfb module, so I'm not sure what the VC specs are.  How did 
you get that info?

>
> Good luck with a new cable.

Thanks.  Wish I had better news.

>
> Bob...
>
>
>

-- 
 		Matthew Saltzman

Clemson University Math Sciences
mjs AT clemson DOT edu
http://www.math.clemson.edu/~mjs