[mythtv-users] OT: Idea for possible workaround to stop bogus EDID data from messing up MythTV

[Michael T. Dean]

On 10/11/2007 02:07 PM, Christopher David Petersen wrote:
> On 10/11/07, Michael T. Dean <mtdean at thirdcontact.com> wrote:
>   
>> On 10/11/2007 01:55 PM, Christopher David Petersen wrote:
>>     
>>> I have a Olevia LT26HVE LCD TV, that I believe is providing bogus EDID
>>> information to my video card (xdpyinfo reports the screen size as
>>> 40x30mm: wrong size, wrong aspect ratio).
>> Why not just tell your video driver to ignore the EDID information?
> I haven't found the option to tell my *SiS* video driver to ignore
> EDID information. I understand that nVidia drivers can use Option
> "UseEDID" "FALSE".
>
> Does anybody know the option for SiS video drivers?

I have to admit I don't know much about the SiS driver.  However, unless
the driver is completely broken, it should a) use the information
provided in the X command-line (or X configuration if none in the
command line) to specify DPI/DisplaySize even if the monitor reports
EDID information or b) allow the user to override the (broken) default
of using EDID information regardless of configuration (as does the
NVIDIA driver).  NVIDIA's default of using EDID info regardless of
configuration is really against the X "way of doing things" (command
line -dpi to the server should take precedence, followed by DisplaySize,
and finally--if neither of the above are specified--defaulting to
EDID-reported info).  So, I'd guess if there's no option listed in the
man page for the driver to disable EDID/DDC (or at least the DPI
information provided by it), choosing the right X options--either a -dpi
argument to the server or DisplaySize in the config file--should work
for you.

And, if all else fails--and you're using the open-source driver--you can
just hack it so sisfb_interpret_edid() always returns false or
something.  That's always safer than hardware modifications :) (though
it prevents mode validations so it would allow you to send through
unusable signals with the wrong modelines).

Mike