Thank you! The TMM overview document was very interesting and highly relevant 
to this discussion: 
http://www.microsoft.com/whdc/system/platform/mobilepc/tmm.mspx
I had never heard of TMM, and have never used Vista, but they have basically 
captured exactly what I was trying to express in the hypothetical use cases - 
they even use the phrase "it just works!" :-)

To summarise: they say it works fine with DVI and that for DVI that it
works without polling using interruptible HPD. For VGA, they say there
are known problems with autodetection, but that they're using periodic
DCC polling using the I2C bus, and that it only works for analog
displays with EDID support, and that they use non-destructive polling
unless requested to detect something by the user, and that non-
destructive polling does not cause any visual artefacts or flashing, and
that the specific implementation for polling is up to the hardware
vendor (maybe it's part of the Windows driver supplied by the hardware
vendor?). For VGA polling, it happens once per second or less. There is
no polling of TV outputs, and TV-out is not really covered very much,
and is doesn't sound like it gets any of the benefits of auto-detection.
Hardware must work with TMM in order to get the top level of Vista
certification.

Bottom line: It is possible to do this, especially for hardware that
already works with this TMM thing. However there would almost certainly
be some older or cheaper display adapters that do not work (if there
wasn't, Microsoft would have no need for a certification requirement),
so there would have to be a white-list of known supported cards, or in X
the driver would have to say if the hardware was capable of this. And
frankly, that's fine - if the hardware can't do it in a non-obtrusive
way, then the hardware can't do it, and that's just the way it is. But,
it is definitely do-able, for at least some hardware, and TMM serves as
a "proof-by-existence" of this.

-- 
Automatically clone video output when plugging a VGA cable into a laptop. An 
"It Just Works" presentation mode.
https://bugs.launchpad.net/bugs/306735
You received this bug notification because you are a member of Ubuntu
Bugs, which is subscribed to Ubuntu.

-- 
ubuntu-bugs mailing list
ubuntu-bugs@lists.ubuntu.com
https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs

Reply via email to