On Wed, May 01, 2002, David Brownell <[EMAIL PROTECTED]> wrote: > > > I have a question about the handling of interrupt URBs: once > > > an interrupt URB has been submitted (usb_submit_urb()), does it have > > > to be resubmitted by the completion routine, or does the USB system > > > automatically re-queue the URB once the completion routine returns ? > > > In the latter case which fields in the URB would need to be set up > > > again ? > > > > Depends on if you set the interval or not. An interval of 0 is what is > > called one shot and it'll be finished when the transfer has completed. > > However, that's a UHCI-specific feature. Avoid it for > drivers that you expect to work on other HCs.
OHCI and EHCI are buggy then I guess. This is a feature that is actually useful and should be implemented. > > If you set the interval to anything other than 0, then it will > > automatically resubmit for you. This is how interrupt URB's are > > typically used. > > Although there are rumblings that the automagic logic should > maybe disappear (in 2.5) in favor of a straight queuing mechanism, > with explicit resubmit ... fewer special cases in the driver model. > > The current automagic resubmission schemes (ISO does it too) > can mask errors, and don't handle some interesting interrupt cases > that are important for writes (OUT to device) or for avoiding a need > to have "USB target drivers" (for Linux embedded in USB devices) > use an excessively different kind of URB API. Yes, I was describing 2.4 behaviour. JE _______________________________________________________________ Have big pipes? SourceForge.net is looking for download mirrors. We supply the hardware. You get the recognition. Email Us: [EMAIL PROTECTED] _______________________________________________ [EMAIL PROTECTED] To unsubscribe, use the last form field at: https://lists.sourceforge.net/lists/listinfo/linux-usb-devel
