On Tuesday 10 October 2006 1:20 pm, Pete Zaitcev wrote: > On Tue, 10 Oct 2006 16:02:54 -0400 (EDT), Alan Stern <[EMAIL PROTECTED]> > wrote: > > On Tue, 10 Oct 2006, Christopher "Monty" Montgomery wrote: > > > > Ah, EHCI (or USB in general) specifies a completion interrupt happens > > > only at the end of a frame? I was suggesting the interrupt be thrown > > > as soon as the URB completes, even if that's mid-frame. > > > Both UHCI and OHCI issue IRQs only at frame boundaries. I believe EHCI > > can issue IRQs at arbitrary uframe boundaries, but I'd have to check the > > spec. However I think ehci-hcd generally sets up the controller to issue > > IRQs only at frame boundaries. Dave knows more about that.
EHCI is set up with a default 1-uframe IRQ latency; it's settable. > Is this the case for all kinds of transfers? I thought this was only true > for Interrupt and ISO, because my testing showed OHCI issuing interrupts > for end of bulk transfers at any time. It seems to depend on the particular implementation of OHCI. I've certainly seen some which only appear to issue IRQs at frame boundaries ... and others which appear happy to issue them at any point between frames. There might be patterns (like "run through the entire schedule once then issue IRQ"), and I also expect that the default "delay IRQ til last packet of URB" setting may affect IRQ scheduling. I'd not make plans that rely on IRQs firing at any particular point, regardless. - Dave ------------------------------------------------------------------------- Using Tomcat but need to do more? Need to support web services, security? Get stuff done quickly with pre-integrated technology to make your job easier Download IBM WebSphere Application Server v.1.0.1 based on Apache Geronimo http://sel.as-us.falkag.net/sel?cmd=lnk&kid=120709&bid=263057&dat=121642 _______________________________________________ linux-usb-devel@lists.sourceforge.net To unsubscribe, use the last form field at: https://lists.sourceforge.net/lists/listinfo/linux-usb-devel
