On Wed, 21 Oct 2009, Clemens Ladisch wrote: > > But with xHCI, the hardware does all the scheduling as soon as an > > altsetting is installed. > > As far as I understand the spec, this is the intended (or at least > allowed) behaviour for all HCs. To my knowledge, the spec doesn't discuss this one way or another. > And it would be a benefit for drivers > if a successful set_interface guaranteed that submitting isoc URBs will > not fail due to missing bandwidth. That's true, but there is a tradeoff. It would mean that the system couldn't overcommit periodic bandwidth, even if the overcommitted resources weren't being used. Doing this would require changing almost all the HCDs, unfortunately. But there's no reason we can't change them one at a time. Alan Stern -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
