Re: [PATCH] usb: dwc3: core: Disable USB2.0 phy suspend when dwc3 acts as host role

[John Youn <John.Youn@synopsys.com>]

On 1/11/2017 11:51 PM, Felipe Balbi wrote:
> 
> Hi,
> 
> Baolin Wang <baolin.wang@linaro.org> writes:
>>> Baolin Wang <baolin.wang@linaro.org> writes:
>>>> When dwc3 controller acts as host role with attaching slow speed device
>>>> (like mouse or keypad). Then if we plugged out the slow speed device,
>>>> it will timeout to run the deconfiguration endpoint command to drop the
>>>> endpoint's resources. Some xHCI command timeout log as below when
>>>> disconnecting one slow device:
>>>>
>>>> [   99.807739] c0 xhci-hcd.0.auto: Port Status Change Event for port 1
>>>> [   99.814699] c0 xhci-hcd.0.auto: resume root hub
>>>> [   99.819992] c0 xhci-hcd.0.auto: handle_port_status: starting port
>>>>                                  polling.
>>>> [   99.827808] c0 xhci-hcd.0.auto: get port status, actual port 0 status
>>>>                                  = 0x202a0
>>>> [   99.835903] c0 xhci-hcd.0.auto: Get port status returned 0x10100
>>>> [   99.850052] c0 xhci-hcd.0.auto: clear port connect change, actual
>>>>                                  port 0 status  = 0x2a0
>>>> [   99.859313] c0 xhci-hcd.0.auto: Cancel URB ffffffc01ed6cd00, dev 1,
>>>>                                  ep 0x81, starting at offset 0xc406d210
>>>> [   99.869645] c0 xhci-hcd.0.auto: // Ding dong!
>>>> [   99.874776] c0 xhci-hcd.0.auto: Stopped on Transfer TRB
>>>> [   99.880713] c0 xhci-hcd.0.auto: Removing canceled TD starting at
>>>>                                  0xc406d210 (dma).
>>>> [   99.889012] c0 xhci-hcd.0.auto: Finding endpoint context
>>>> [   99.895069] c0 xhci-hcd.0.auto: Cycle state = 0x1
>>>> [   99.900519] c0 xhci-hcd.0.auto: New dequeue segment =
>>>>                                  ffffffc1112f0880 (virtual)
>>>> [   99.908655] c0 xhci-hcd.0.auto: New dequeue pointer = 0xc406d220 (DMA)
>>>> [   99.915927] c0 xhci-hcd.0.auto: Set TR Deq Ptr cmd, new deq seg =
>>>>                                  ffffffc1112f0880 (0xc406d000 dma),
>>>>                                  new deq ptr = ffffff8002175220
>>>>                                  (0xc406d220 dma), new cycle = 1
>>>> [   99.931242] c0 xhci-hcd.0.auto: // Ding dong!
>>>> [   99.936360] c0 xhci-hcd.0.auto: Successful Set TR Deq Ptr cmd,
>>>>                                  deq = @c406d220
>>>> [   99.944458] c0 xhci-hcd.0.auto: xhci_hub_status_data: stopping port
>>>>                                  polling.
>>>> [  100.047619] c0 xhci-hcd.0.auto: xhci_drop_endpoint called for udev
>>>>                                  ffffffc01ae08800
>>>> [  100.057002] c0 xhci-hcd.0.auto: drop ep 0x81, slot id 1, new drop
>>>>                                  flags = 0x8, new add flags = 0x0
>>>> [  100.067878] c0 xhci-hcd.0.auto: xhci_check_bandwidth called for udev
>>>>                                  ffffffc01ae08800
>>>> [  100.076868] c0 xhci-hcd.0.auto: New Input Control Context:
>>>>
>>>> ......
>>>>
>>>> [  100.427252] c0 xhci-hcd.0.auto: // Ding dong!
>>>> [  105.430728] c0 xhci-hcd.0.auto: Command timeout
>>>> [  105.436029] c0 xhci-hcd.0.auto: Abort command ring
>>>> [  113.558223] c0 xhci-hcd.0.auto: Command completion event does not match
>>>>                                  command
>>>> [  113.569778] c0 xhci-hcd.0.auto: Timeout while waiting for configure
>>>>                                  endpoint command
>>>>
>>>> The reason is it will suspend USB phy to disable phy clock when
>>>> disconnecting the slow USB decice, that will hang on the xHCI commands
>>>> executing which depends on the phy clock.
>>>>
>>>> Thus we should disable USB2.0 phy suspend feature when dwc3 acts as host
>>>> role.
>>>>
>>>> Signed-off-by: Baolin Wang <baolin.wang@linaro.org>
>>>> ---
>>>>  drivers/usb/dwc3/core.c |   14 ++++++++++++++
>>>>  1 file changed, 14 insertions(+)
>>>>
>>>> diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
>>>> index 9a4a5e4..0b646cf 100644
>>>> --- a/drivers/usb/dwc3/core.c
>>>> +++ b/drivers/usb/dwc3/core.c
>>>> @@ -565,6 +565,20 @@ static int dwc3_phy_setup(struct dwc3 *dwc)
>>>>       if (dwc->revision > DWC3_REVISION_194A)
>>>>               reg |= DWC3_GUSB2PHYCFG_SUSPHY;
>>>>
>>>> +     /*
>>>> +      * When dwc3 controller acts as host role with attaching one slow speed
>>>> +      * device (like mouse or keypad). Then if we plugged out the slow speed
>>>> +      * device, it will timeout to run the deconfiguration endpoint command.
>>>> +      * The reason is it will suspend USB phy to disable phy clock when
>>>> +      * disconnecting slow speed decice, which will affect the xHCI commands
>>>> +      * executing.
>>>> +      *
>>>> +      * Thus we should disable USB 2.0 phy suspend feature when dwc3 acts as
>>>> +      * host role.
>>>> +      */
>>>> +     if (dwc->dr_mode == USB_DR_MODE_HOST || dwc->dr_mode == USB_DR_MODE_OTG)
>>>> +             reg &= ~DWC3_GUSB2PHYCFG_SUSPHY;
>>>
>>> which version of the core you're using? Recent version (since 1.94A,
>>
>> My version is 2.80a.
>>
>>> IIRC) can manage core suspend automatically. Also, this patch of yours
>>> will cause a power consumption regression.
>>
>> Yes, it can manage core suspend automatically, that is the problem.
>> When plugging out one mouse or keypad device, the phy will suspend
>> automatically to disable the phy clock. But now the disconnecting
>> process is not finished, and some xHCI commands (like deconfiguration
>> endpoint command to drop endpoint resources) need depend on the phy
>> clock, which will hang on the system to timeout the command or abort
>> command ring to halt the xHCI.
>>
>> I agree with you it will cause a power consumption regression, but it
>> will cause serious problem if not. Do you have some suggestion?
> 
> sorry for the long delay. This was lost in my inbox.
> 
> I'm not sure this patch is the best solution. There's no mention in
> Databook that we should avoid PHY suspend when acting as host. Adding
> John here to see if John has any idea of how to fix this.
> 

I'm not familiar enough with XHCI side of things to say.

I'll ask around to see if anyone has an idea.

Regards,
John