On Sun, 11 Mar 2007, Martin Drab wrote: > Hi, > > how independent are different endpoints of the same alternate interface?
They are completely independent. In theory anyway; individual devices may have specific restrictions. > Is it possible eg. to schedule multiple URBs to a bulk IN endpoint (say > EP3IN) and simultaneously schedule a control URB to the setup OUT endpoint > (say > EP0OUT) and expect, that the control URB would succeed immediatelly even > if all the scheduled bulk URBs haven't been serviced yet? Well, you certainly can submit all those URBs. There would be no guarantee about what order they would complete in, or how quickly. And some devices are definitely known to crash if you send them a control URB while they are busy doing something else. > With > isochronnous transfers instead of the bulk transfers, it works fine. But > it doesn't work with the bulk transfers. > > The thing is I'd like to stream data from a device with a bulk transfer, > while still being able to send control commands (e.g. for requesting > current status of the device or changing some of its internal settings) > during the bulk transfers. > > I always get stuck when trying this. Multiple bulk URBs submission seems > to work on its own, but when I then issue the first control urb, all > transmissions seem to freeze halfway. Now, it may be a bug in my driver > code, but I'd like to know whether it even should work as I expect it to, > or whether I shouldn't even try it, because for some reason it is not > supposed to work. It's supposed to work. The fact that it doesn't could be due to a bug in your driver or a bug in the device. Try using usbmon (see Documentation/usb/usbmon.txt) to find out what data is actually being transferred. That at least should tell you if your driver is behaving as intended. Alan Stern ------------------------------------------------------------------------- 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
