On Tue, 26 Oct 2004, Geoff Oakham wrote: > Hey Alan, > > Unfortunately I haven't had any luck fixing this timing issue, so I've > returned to seek wisdom and guidance. I've tried: > > -capping the average transfer speed in my driver > -looking for similar behaviour in the Windows driver > > Everything I've observed* suggests (to me) a lurking race condition. > There's only two places it could be lurking: > > -my driver > -the uhci host driver > > Since the linux-usb implementation is 100% bug-free, my code is the > bug's likely home. Should I be holding any locks when I call > usb_control_msg() or usb_bulk_msg()?
You certainly shouldn't hold any spinlocks, since those routines need to sleep. There's nothing wrong with holding a semaphore, but you don't _need_ to hold any locks at all. Does your driver print a debug message every time it submits an URB or calls one of those routines? By checking the log you could verify that events aren't happening out of sequence. > any insight would be appreciated; thanks in advance, Have you eliminated the possibility of other programs running in the background also trying to communicate with your device (some Gnome/hotplug programs do that)? Have you turned on USB debugging in the kernel configuration? If something is going wrong, maybe it will show in the debugging log. > Geoff > > * Just to recap: this bug happens when my system is heavily loaded > with lots of disk activity. (Ie, lots of hardware and software > interrupts.) Also, the only tester that reported the same problem was > using a dual AMD64. (Sounds ripe for race conditions.) I'm not aware of any race conditions. (Of course, if I did know of one I probably would have fixed it already!) Alan Stern ------------------------------------------------------- This SF.Net email is sponsored by: Sybase ASE Linux Express Edition - download now for FREE LinuxWorld Reader's Choice Award Winner for best database on Linux. http://ads.osdn.com/?ad_id=5588&alloc_id=12065&op=click _______________________________________________ [EMAIL PROTECTED] To unsubscribe, use the last form field at: https://lists.sourceforge.net/lists/listinfo/linux-usb-devel
