On Fri, 3 Jun 2011, Soho Soho123 wrote: > > I don't understand. If the camera is disconnected from the USB bus, > > there's nothing to test! > > Soho: I mean :there is not any streaming data to client(networking). > Not USB disconnect. Oh, okay. Now I understand. > > Maybe you can run a test where you print out the CPU cycle counter: > > > > Just before the start of the big "for" loop in scan_periodic() > > (also print out the values of now_uframe and clock); > > > > Just after the "restart:" statement label (also print out the > > value of now_uframe); > > > > And just after the call to itd_complete(). > > > > Try this for the 2.6.30 kernel and also with the updated ehci-hcd > > driver. Seeing the numbers might help me to figure out the problem. > > > Soho: Let me explain how to measure CPU cycle that we used: > there is a "enter point" and a "exit point" , then we > calculate cpu cycle : > count in exit point - count in enter point > "enter point" and "exit point" should be a pair, such that > we can know the count from begin to end > > Could you explain the meaning of yours? As my understanding, > 1. I put the enter point in before "big" for loop, but where I can > put the exit point for the first pair? > 2. I put the enter point after the line "restart" label, but where I > can put the exit point for this pair? Maybe you can do this: Before the big "for" loop, put an exit point, then print out the cycle count, now_uframe, and clock, then put an enter point. Similarly, just after the "restart:" statement label, put an exit point, then print out the cycle count and now_uframe, then put an enter point. And just after the call to itd_complete(), put an exit point, then print out the cycle count, then put an enter point. An enter point would not be matched with any particular exit point. But it should still work (except perhaps for the very first time an exit point is reached). Alan Stern -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
