On Fri, 13 Oct 2006, Open Source wrote: > Hi Wolfgang (and all), > > Thanks for the input. However, I am not understanding > exactly why kernel mode is treated any differently than > user mode for this sort of thing. I am looking at the code > in ehci-q.c and ehci-hcd.c. > > It seems like the unlinking of completed URBs > happens asynchronously on a timer. This is a > surprise to me since I thought this was happening > on an IRQ from the host controller. But if what I'm > surmising is correct it would explain everything > I am seeing. I'm not able to ascertain how > user mode drivers are treated differently than > kernel mode drivers in this regard. From what I > can tell, all drivers would be broken equally! > Can anyone who has more experience > with this code confirm this for me?
I don't think so. You must be mis-reading the code. The only timers used in ehci-hcd are a couple of watchdogs; they shouldn't affect the normal URB completions which occur within ehci_work(), called by ehci_irq(). What Wolfgang meant was that user processes are subject to unpredictable delays from all kinds of sources. Alan Stern ------------------------------------------------------------------------- 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
