Re: [Qemu-devel] [qemu-devel][RFC] Enable usb with default options

[Benjamin Herrenschmidt]

On Thu, 2012-06-07 at 11:50 +0200, Hans de Goede wrote:
> > In the meantime, this approach you experimented with would be very
> > useful for us  in the common case where there is no isochronous device.
> > It shouldn't be too hard for the emulator to switch back to "normal"
> > frames if an ISO EP is present, no ?
> 
> That should be possible yes. Note though that although slowing down the
> timer will only break isoc. stuff, it will for example also slow down
> usb mass storage devices.

Sure, I was thinking about something a bit smarter that would "throttle"
the timer based on what kind of EPs have active TDs (that might imply a
delay reacting to a brand new TD but with a bit of smarts such as a
delay before throttling back, "completions" from sub-devices in qemu
triggering an immediate processing, etc... should be doable).

However...

> > That would solve the 99% case of just keyboard and mouse on all those
> > machines.
> >
> > Do you have some patches around from those earlier experiments that we
> > could try to revive, at least for OHCI ?
> 
> No, I only did this for EHCI, which may still have an option to enable
> this today. Gerd may have done this for UHCI too, Gerd ? 

Ok, what I really care about is OHCI, so at this point, it's basically
not there. So either I decide what Linux does today to enable PM is good
enough or I get my hands dirty :-)

We'll see, it's not an emergency at this stage, I might come up with
something if I get a chance.

Cheers,
Ben.