desperately seeking "IgnoreEDID"

[Robert P. J. Day]

Quoting Roger Heflin <rogerheflin at gmail.com>:

> Robert P. J. Day wrote:
>>  i'm still fighting to get my WUXGA display laptop to ignore the   
>> EDID information coming back from a video device, so i simplified   
>> the problem and here's what's happening so far.
>>
>>  i have a fresh install of f9 on an aging dell inspiron 9200 with a  
>>  full WUXGA display, and i'm trying to drive a full-res WUXGA  
>> signal  into an external video processing device that is  
>> (theoretically)  supposed to be able to handle that.
>>
>>  if i connect my laptop to an external full WUXGA flat-panel   
>> (Samsung) display, no problem -- the image is perfect,   
>> pixel-for-pixel, and full WUXGA on both laptop and external monitor.
>>
>>  if, however, i connect the laptop to that external video device,   
>> that external device is (apparently) returning EDID information   
>> that claims to not be able to accept full WUXGA (even though it   
>> should be able to, allowing us to conclude that its EDID info is   
>> simply wrong and we'll have to fix that at some point.)  and doing   
>> that also forces my laptop down to a lower resolution.  argh.
>>
>>  i figured that a simple solution is to just configure my laptop to  
>>  ignore incoming EDID and keep driving the signal at full WUXGA,  
>> but  i can't get that to work.  here's my change to  
>> /etc/X11/xorg.conf  (text copied by hand as the laptop is not on  
>> the net):
>>
>>  Section "Device"
>>    Identifier "Videocard0"
>>    Driver     "Radeon"
>>    Option     "IgnoreEDID" "True"   <-- added this
>>  EndSection
>>
>>  as an experiment, i connected the laptop to a flat panel dell   
>> 1280x1024 display to see what would happen, logged out, logged back  
>>  in, and the Xorg log file contains the line:
>>
>>  (**) RADEON(0): Option "OptionEDID" "True"
>>
>> which i would have thought confirms the ignoring of incoming EDID,   
>> but i still get the same effect of having my laptop resolution   
>> dropped noticeably (in this case, to 1152x864, according to   
>> "xdpyinfo"), ostensibly to accommodate the decreased resolution of   
>> the external monitor.
>>
>>  so,
>>
>>  1) is there something else i should be trying to get my laptop to   
>> totally ignore the fact that it's connected to an external device   
>> that claims to not be capable of full WUXGA, and
>>
>>  2) if i succeed in ignoring EDID with this test flat panel,   
>> obviously, the flat panel can't handle that (full WUXGA) signal so   
>> i'm not expecting to get a useful image, but is there a chance i   
>> could damage the flat panel?
>>
>>  open to suggestions.
>>
>> rday
>>
>>
>
> You might try UseEDID as:
>         Option      "UseEDID" "FALSE"
>
> And see if it works any better.

nope, that made no difference.  in fact, from the X log file,
it doesn't appear that it had any effect at all.  at least with

   Option "IgnoreEDID" "True"

the contents of the X log file suggest that EDID processing is
cancelled (even though it clearly isn't).  with the option above,
the X log file shows that EDID processing is occurring normally.

   in short, still doesn't solve the problem.

rday