Hi Alan, > On Tue, Aug 08, 2023 at 10:03:39AM +0000, Xu Yang wrote: > > Hi Alan, > > > > > On Sat, Jul 29, 2023 at 06:55:07AM +0000, Xu Yang wrote: > > > > Many thanks for your comments and suggestions. > > > > > > > > Yes, there is a "live" variable in scan_isoc() to handle the case where > > > > root hub has stopped periodic schedule. I have rechecked the root cause > > > > of the issue , that is the USB controller has disabled the port (PE cleared) > > > > and asserted USBERRINT when frame babble is detected, but PEC is not > > > > asserted. Therefore, the SW didn't aware that port has been disabled. > > > > The periodic schedule keeps running at this moment. Then the SW keeps > > > > sending packets to this port, but all of the transfers will fail. But periodic > > > > schedule will also be disabled after a period of time. Finally, all of the linked > > > > itds are penging there. The code can't enter into scan_isoc() if only USBERRINT > > > > is asserted. > > > > > > That's not true. The io_watchdog timer continues to fire periodically > > > (at 100 ms intervals) as long as isoc_count > 0. The timer's handler is > > > ehci_work(), which calls scan_isoc() if isoc_count > 0. > > > > Yes, the io_watchdog timer will cleanup the isoc periodically as long as > > isoc_count > 0. > > > > I did see all of the linked itds are pending there in my case at the end. After my > > debug, I found the chipidea/host.c had set ehci->need_io_watchdog to 0 which > > will have impact on turn_on_io_watchdog(). > > > > The host has enabled 1 intr endpoint and 2 isoc endpoints from USB camera. > > Therefore, ehci->intr_count is always 1 and ehci->isoc_count is changing from > > time to time during camera is running. When PE is cleared by HW, isoc_count > > may be decreased to 0 after scan_isoc(). When turn_on_io_watchdog() is called, > > EHCI_HRTIMER_IO_WATCHDOG event will not be enabled due to isoc_count=0 > > and need_io_watchdog=0 too. When isoc urb is submited again, enable_periodic() > > will still not enable EHCI_HRTIMER_IO_WATCHDOG event due to periodic_count>0. > > Ooh, that's a bug. enable_periodic() should call turn_on_io_watchdog() > no matter what value periodic_count has. Would you like to fix it? Sure. Will try to fix it. Thanks, Xu Yang > > Alan Stern
