On Sunday 08 October 2006 4:37 pm, Christopher "Monty" Montgomery wrote: > > > For example, let's say an URB is submitted for slot S, just as S's > > > microframe is starting. ehci-hcd adds the URB into the hardware schedule; > > > was it in time for the controller to see it? > > Right now, that attempt would be outright rejected. ehci-sched will > not (and never would) schedule into the currently active frame. In > fact, it would not schedule into any frame within 'SCHEDULE_SLOP' of > the active frame. I did not change that behavior.
FYI that "slop" was to handle issues like (a) EHCI caching ISO entries, which behavior is allowed but only loosely specified, (b) delays associated with e.g. reading the frame counter just before it rolls over, or from the work done during submission, (c) schedule wraparound, e.g. to avoid running into the oldest-scheduled URBs ... basically, to flag zones on both near and far ends of the schedule as do-not-enter, since they can't be scheduled reliably. > > > No way to know until the > > > microframe is finished. The only way ehci-hcd can make an accurate report > > > in this case is to _always_ report that the slot was missed -- not even > > > _try_ to add it into the hardware schedule -- even if it might have been > > > possible for the slot to be filled. > > ...or check the uframe clock when the schedule is complete and if it > still precedes the slot... > > [or are you worried about caching and propogation of changes?] You'd have to ask Alan, who wrote that. And as noted, the EHCI code should _also_ be checking that case. ------------------------------------------------------------------------- Take Surveys. Earn Cash. Influence the Future of IT Join SourceForge.net's Techsay panel and you'll get the chance to share your opinions on IT & business topics through brief surveys -- and earn cash http://www.techsay.com/default.php?page=join.php&p=sourceforge&CID=DEVDEV _______________________________________________ linux-usb-devel@lists.sourceforge.net To unsubscribe, use the last form field at: https://lists.sourceforge.net/lists/listinfo/linux-usb-devel
