[Libdlo] Tips for setting up displaylink with Xinerama

[Christoph Rissner]

Hi,

> I'm surprised there's no /sys/class/graphics tree (some of my other
> ...

Sorry, checking again shows the file exists under
  /sys/class/graphics/fb1/edid

I didn't know fb1 is a symlink ...

> One thing I'd check - you said EDID read appeared to be working on
> Windows, but wasn't sure -- can you check the display control panel, and
> see if it's offering you modes that are greater than the monitor's
> capabilities -- that would be a sign that edid is not getting returned
> there, either.

I just did, and you are right (which makes me feel a little stupid...).
Seems like Windows just offers more or less random modes, it's possible 
that I configured it after installing the driver, but I can't remember.

Sorry I didn't try this at the beginning.

Now that I have to worry about modelines again, I used parse-edid 
(http://www.polypux.org/projects/read-edid/) to compute the modeline(s):

$ src/read-edid-2.0.0/parse-edid < ~/tmp/edid
src/read-edid-2.0.0/parse-edid: parse-edid version 2.0.0
src/read-edid-2.0.0/parse-edid: EDID checksum passed.

         # EDID version 1 revision 3
Section "Monitor"
         # Block type: 2:0 3:fd
         # Block type: 2:0 3:fc
         Identifier "SyncMaster"
         VendorName "SAM"
         ModelName "SyncMaster"
         # Block type: 2:0 3:fd
         HorizSync 30-81
         VertRefresh 56-75
         # Max dot clock (video bandwidth) 140 MHz
         # Block type: 2:0 3:fc
         # Block type: 2:0 3:ff
         # DPMS capabilities: Active off:yes  Suspend:no  Standby:no

         Mode    "1280x1024"     # vfreq 60.020Hz, hfreq 63.981kHz
                 DotClock        108.000000
                 HTimings        1280 1328 1440 1688
                 VTimings        1024 1025 1028 1066
                 Flags   "+HSync" "+VSync"
         EndMode
         # Block type: 2:0 3:fd
         # Block type: 2:0 3:fc
         # Block type: 2:0 3:ff
EndSection

I tried adding
   Option "IgnoreEDID" "on"
to the Monitor section but X keeps crashing:
(II) DL(1): Output udlfb using monitor section Monitor1
(EE) DL(1): Unknown EDID version 0

Backtrace:
0: /usr/bin/X(xorg_backtrace+0x3b) [0x813158b]
1: /usr/bin/X(xf86SigHandler+0x9e) [0x80bd1ce]
2: [0xb7f62400]
3: /usr/bin/X(InitOutput+0x4e9) [0x80af469]
4: /usr/bin/X(main+0x1cb) [0x8071e3b]
5: /lib/libc.so.6(__libc_start_main+0xe6) [0xb7b27b86]
6: /usr/bin/X() [0x80714b1]

Is this related to the displaylink driver?
How can I tell X to ignore EDID for a single monitor?

Thanks for your help,
Christoph