On Sun, Oct 13, 2002, David Brownell <[EMAIL PROTECTED]> wrote: > Dan Streetman wrote: > > I have to agree with JE, there should be a common API for drivers to > > reserve bandwidth on a per-ep basis, and then any URBs submitted are > > guaranteed not to fail from a shortage of bandwidth. > > (I didn't get such a message from him.) > > That's no change from today, unless you mean "new API". > > Since some point in the 2.3 development cycle, device drivers use the > common usb_submit_urb() API to request bandwidth. And that bandwidth > is released when that URB's endpoint is no longer active. It's a > simple model that works ... and should continue to work.
It's a simple model that has a design flaw. It has the same race condition. However, the important part of it, the calculations, can be built on. We just need to fix the way bandwidth is reserved. > > However, I don't think BW can be calculated effectively by common code, it > > is dependent on the HCD. > > That's how it behaves already, with the different HCDs putting more > or less work into their scheduling policy. That's how it is done now, but since the original code was the same across all HCD's, I don't see why it should differ between HCD's. USB 1.1 is the same across all HCD's. The only thing I can think of that would differ is what frames interrupt URB's get scheduled into. Regardless, this isn't a big deal. If it's the same, put it into the core, if it isn't, put it into the HCD's. JE ------------------------------------------------------- This sf.net email is sponsored by:ThinkGeek Welcome to geek heaven. http://thinkgeek.com/sf _______________________________________________ [EMAIL PROTECTED] To unsubscribe, use the last form field at: https://lists.sourceforge.net/lists/listinfo/linux-usb-devel
