Intel i915GM with SDVO CH7021A support?

[will]

Hi,

A few months ago I got a version of the mode setting Intel 915 driver from a
git tree posted on airlied's live journal. With a bit of fiddling and
tweaking this has been working very well and I can get very close to the
refresh rates required for video etc.

I've had no success with the CH7021A SDVO support under linux at all.
Chrontel refuse to supply any details about how to program the chip. I did
manage to get the DVI working with the IEGD binary driver but it wouldn't
recognise or work the CH7021A at all. I'd really like to get the CH7021A
working as it supports HDTV, SCART out and exact TV refresh rates and spec
etc etc. Without proper support it's impossible to adjust the internal
parameters as it is with the Windows driver.

If any one has any suggestion or can help me it would be appreciated. I'm
quite happy to try any experimental code or hack something together if there
is a bit of detail about how to get the 7021 to respond available. I
understand it may be possible to snoop the I2C bus and potentially work out
what is going on with the SDVO. Would this be a viable method or would I
just be wasting my time trying? I should probably know the answer to this
but it would help if someone could confirm this... Once the PC has booted up
is it possible to switch the SDVO 7021A TV out on using a BIOS call, I had a
brief look in the VESA spec but I could easily have missed this. Presumably
if a BIOS call is available presumably the snooping method will work...
otherwise would it be possible / practical to snoop the I2C bus at bootup
using some sort of TSR when the TV Out is enabled?

Thanks for any help anyone can provide

Will Wiseman