[intel + sisusb + xinerama + randr 1.2, oh my] this should work, but doesn't.

[Adam Williamson]

Hi, all. Well, consider this 'something that should work, but
doesn't'...

I have a laptop (Lenovo 3000 V100) with an Intel chip. I want to have
two external monitors. Unfortunately, the machine only has one external
VGA port. I can use the internal display along with an external monitor
just fine, with RandR 1.2 (I'm on today's git master state of the intel
driver). But that just ain't cool enough.

So I went out and picked up something rejoicing in the name of a Tritton
See2, which is a USB graphics adapter. It works, with the sisusb driver.
If I just set up my xorg.conf to ignore the Intel chip entirely and only
use the sisusb device, I can get a perfectly good single-head setup
through it.

However, unfortunately, putting the whole shebang together doesn't seem
to work. I set up an xorg.conf which should have 'screen1' on the Intel
adapter (encompassing my internal and external panels) and 'screen2' on
the Tritton adapter both enabled, using Xinerama, hit startx, and it
falls over with a signal 11 in the Intel driver's RandR 1.2 code. Even
if I simplify it to just one output connected to intel and one to sisusb
(a.k.a. unplug the intel's external monitor), no go.

So far the feedback I've got is basically "sorry, it ain't going to
work". It seems that using an RandR 1.2 driver and a RandR pre-1.2
driver at the same time just won't fly, and even if sisusb supported
RandR 1.2, RandR 1.2 isn't currently capable of handling multi-adapter
setups.

So the point of this mail is twofold. One, if anyone has any ideas on
how to make the setup work for me, that would be great. I'll probably
experiment with using i810 instead of intel and see if I can get it
going that way, but then of course I have all the excitement of making
i810 output 1680x1050 reliably, which wasn't much fun the first time
around.

Two, it would be nice if this worked. =) I don't really know what's
involved technically speaking to make it all more or less Just Work, or
how feasible that would be, but if someone could do it, that'd be
lovely. Or just some info on what the timetable is for the various bits
of the problem to get fixed (multi-adapter setups working with RandR
1.2, sisusb being ported to RandR 1.2, anything else that's relevant).

I'm not kidding myself that this is exactly a common setup (as far as I
can tell there's one other person who's used this Tritton thingy with
Linux. In Japan. On an OLPC...), but there's probably at least a few
other people out there who'd like to do something similar, and it just
strikes me as a sufficiently technically interesting problem that
someone might be interested in fixing it just for the sake of it.

Oh, and it works on Windows, according to the reviews of the Tritton
thingy. We can't be worse than Windows, right? :)

Thanks, all :)
-- 
adamw