Messages in this thread | | | Date | Thu, 27 Aug 2015 14:18:13 +0300 | From | Mathias Nyman <> | Subject | Re: [PATCH 0/5] usb: xhci: Fix breakage on dual-role case |
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On 20.08.2015 10:09, Roger Quadros wrote: > Hi Mathias,
Hi
> > On 18/08/15 13:39, Roger Quadros wrote: >> Hi, >> >> Plugging and unplugging a USB-OTG adapter with a USB device into a >> am437x-gp-evm dual-role port (USB1) causes XHCI to malfunction >> and USB device to be no longer detected after a few iterations. >> >> The triggering case is so >> 1) USB1 in peripheal mode >> 2) plug OTG adapter with USB device >> 3) USB1 switches to host mode >> 4) Detects new USB device >> 5) unplug OTG adapter >> 6) OTG core tries to remove host controller while new device >> is being processed. >> >> At 6 some races are observed in the XHCI driver causing it to >> malfunction. See kernel log at the end of this mail. >> >> This series tries to address some of the issues. >> Althouth it is not 100% fool proof yet and XHCI can still get >> stuck up for a few seconds occasionally, it did recover always >> in a max of 10 seconds and the USB device was enumerated after >> that. >> >> During a dual-role switch, usb_remove_hcd() and usb_add_hcd() >> will be called consecutively for both Shared and Primary >> HCDs. This can happen asynchronously and we have to be prepared >> for it. >> > > Even after this series I do occasionally see a delay of 5 seconds > during adapter detach. (please see kernel log below). > > Is it possible to further optimize so that when xhci_stop is called > we don't depend entirely on timeout timers to stop queued commands?
Yes, sounds reasonable. Command timer and ring could probably be stopped, remaining commands aborted and returned.
-Mathias
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