[Openchrome-users] DVI DDC on Jetway DVI daughter-card

[Phil Endecott]

Dear Experts,

I have a Jetway J7F2 board (CN700 based) with a DVI daughter-board that 
has a VT1632A DVI chip on it.  I understand from the wiki that this 
chip is not officially supported, but having enabled it in the BIOS it 
works for me.

The only problem is that it does not appear to read DDC from the DVI 
interface.  If I start X with only DVI connected I get a default low 
resolution screen; if I boot with both DVI and VGA connected I get the 
correct resolution on the DVI output.

I believe that the VT1632A doesn't have any DDC I2C functionality so my 
guess is that the DDC I2C signals from my DVI connector are either not 
connected at all, in which case there is obviously not much I can do, 
or they go straight through to the motherboard and into the main 
chipset.  In the latter case, maybe it's not difficult for the driver 
to probe them?

I'll put a couple of X logs here:

http://chezphil.org/tmp/haiti_x_log_dvi_only
http://chezphil.org/tmp/haiti_x_log_dvi_and_vga

Apologies if this has been discussed before; I haven't found anything 
when searching.  Also I'd be interested to hear from anyone else using 
one of these Jetway DVI daughter boards; I have a suspicion that mine 
might suffer from overheating.  [If you want a laugh: earlier I 
attempted to test my overheating theory with a can of freezer spray - 
and picked up the Spray Glue instead.  The inside of the box is now a 
sticky mess.  But I now know that spray glue does not conduct electricity...]


Cheers,  Phil.