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Re: [RFC] usb: host: xhci: Remove the watchdog timer and use command timer to watch stop endpoint command

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On 1 December 2016 at 14:04, Baolin Wang <baolin.wang@linaro.org> wrote:
> Hi Baolu,
>
> On 1 December 2016 at 13:45, Lu Baolu <baolu.lu@linux.intel.com> wrote:
>> Hi,
>>
>> On 11/30/2016 05:02 PM, Baolin Wang wrote:
>>> If the hardware never responds to the stop endpoint command, the
>>> URBs will never be completed, and we might hang the USB subsystem.
>>> The original watchdog timer is used to watch if one stop endpoint
>>> command is timeout, if timeout, then the watchdog timer will set
>>> XHCI_STATE_DYING, try to halt the xHCI host, and give back all
>>> pending URBs.
>>>
>>> But now we already have one command timer to control command timeout,
>>> thus we can also use the command timer to watch the stop endpoint
>>> command, instead of one duplicate watchdog timer which need to be
>>> removed.
>>>
>>> Meanwhile we don't need the 'stop_cmds_pending' flag to identy if
>>> this is the last stop endpoint command of one endpoint. Since we
>>> can make sure we only set one stop endpoint command for one endpoint
>>> by 'EP_HALT_PENDING' flag in xhci_urb_dequeue() function. Thus remove
>>> this flag.
>>
>> I am afraid you can't do this. "stop_cmds_pending" was added
>> to fix the problem described in the comments that you want to
>> remove. But I didn't find any fix of this problem in your patch.
>
> Now we can not pending another stop endpoint command for the same one
> endpoint, since will check 'EP_HALT_PENDING' flag in
> xhci_urb_dequeue() function to avoid this. But after some
> investigation, I think I missed the stop endpoint command in
> xhci_stop_device() which did not check the 'EP_HALT_PENDING' flag,
> maybe need to add 'EP_HALT_PENDING' flag checking in
> xhci_stop_device() function. DId I miss something else? Thanks.

Sorry, wait, we will wait for the stop endpoint command finished in
xhci_stop_device() function. So we don't need check 'EP_HALT_PENDING'
flag as the orignal code did.

-- 
Baolin.wang
Best Regards

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[RFC] usb: host: xhci: Remove the watchdog timer and use command timer to watch stop endpoint command Baolin Wang <baolin.wang@linaro.org> - 2016-11-30 10:10 +0100
  Re: [RFC] usb: host: xhci: Remove the watchdog timer and use command  timer to watch stop endpoint command Mathias Nyman <mathias.nyman@linux.intel.com> - 2016-11-30 15:10 +0100
    Re: [RFC] usb: host: xhci: Remove the watchdog timer and use command  timer to watch stop endpoint command Baolin Wang <baolin.wang@linaro.org> - 2016-12-01 06:00 +0100
      Re: [RFC] usb: host: xhci: Remove the watchdog timer and use command  timer to watch stop endpoint command Mathias Nyman <mathias.nyman@linux.intel.com> - 2016-12-01 14:30 +0100
        Re: [RFC] usb: host: xhci: Remove the watchdog timer and use command  timer to watch stop endpoint command Baolin Wang <baolin.wang@linaro.org> - 2016-12-02 03:50 +0100
  Re: [RFC] usb: host: xhci: Remove the watchdog timer and use command  timer to watch stop endpoint command Lu Baolu <baolu.lu@linux.intel.com> - 2016-12-01 06:50 +0100
    Re: [RFC] usb: host: xhci: Remove the watchdog timer and use command  timer to watch stop endpoint command Baolin Wang <baolin.wang@linaro.org> - 2016-12-01 07:10 +0100
    Re: [RFC] usb: host: xhci: Remove the watchdog timer and use command  timer to watch stop endpoint command Baolin Wang <baolin.wang@linaro.org> - 2016-12-01 07:10 +0100
      Re: [RFC] usb: host: xhci: Remove the watchdog timer and use command  timer to watch stop endpoint command Lu Baolu <baolu.lu@linux.intel.com> - 2016-12-01 07:40 +0100
        Re: [RFC] usb: host: xhci: Remove the watchdog timer and use command  timer to watch stop endpoint command Baolin Wang <baolin.wang@linaro.org> - 2016-12-01 08:40 +0100
          Re: [RFC] usb: host: xhci: Remove the watchdog timer and use command  timer to watch stop endpoint command Lu Baolu <baolu.lu@linux.intel.com> - 2016-12-01 08:50 +0100
            Re: [RFC] usb: host: xhci: Remove the watchdog timer and use command  timer to watch stop endpoint command Baolin Wang <baolin.wang@linaro.org> - 2016-12-01 09:10 +0100
              Re: [RFC] usb: host: xhci: Remove the watchdog timer and use command  timer to watch stop endpoint command Lu Baolu <baolu.lu@linux.intel.com> - 2016-12-02 02:20 +0100
                Re: [RFC] usb: host: xhci: Remove the watchdog timer and use command  timer to watch stop endpoint command Baolin Wang <baolin.wang@linaro.org> - 2016-12-02 03:50 +0100

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