Re: [edk2-devel] [PATCH v2 1/1] MdeModulePkg/XhciDxe: Fix Broken Timeouts

["Wu, Hao A" <hao.a.wu@intel.com>]

> -----Original Message-----
> From: devel@edk2.groups.io <devel@edk2.groups.io> On Behalf Of Henz,
> Patrick
> Sent: Friday, September 11, 2020 2:43 AM
> To: devel@edk2.groups.io; Wu, Hao A <hao.a.wu@intel.com>; Ni, Ray
> <ray.ni@intel.com>
> Cc: Wang, Jian J <jian.j.wang@intel.com>
> Subject: Re: [edk2-devel] [PATCH v2 1/1] MdeModulePkg/XhciDxe: Fix
> Broken Timeouts
> 
> Hi Hao and Ray,
> 
> In regards to the behavior when Timeout == 0, I did try to account for that in
> my initial patch with the following logic:
> 
> 	(0 ==
> Timeout)?(EFI_TIMER_PERIOD_MICROSECONDS(0xFFFFFFFF)):(EFI_TIMER_
> PERIOD_MILLISECONDS(Timeout))
> 
> This results in a timeout that happens sooner than what the current code
> would produce, but it falls in line with what the original code seemed to
> intend to do. Ray suggested that I enhance the code by not creating the
> timer event when Timeout is 0, which I assumed meant that XhcExecTransfer
> () would just return. I personally think it would be a good idea to keep this
> behavior in the code, but would like Ray's input on the matter. Appreciate


I prefer to keep the origin behavior.
Ray, what is your comment on this?

Best Regards,
Hao Wu


> the help!
> 
> Thanks,
> Patrick Henz
> 
> -----Original Message-----
> From: devel@edk2.groups.io [mailto:devel@edk2.groups.io] On Behalf Of
> Wu, Hao A
> Sent: Wednesday, September 2, 2020 9:25 PM
> To: devel@edk2.groups.io; Henz, Patrick <patrick.henz@hpe.com>; Ni, Ray
> <ray.ni@intel.com>
> Cc: Wang, Jian J <jian.j.wang@intel.com>
> Subject: Re: [edk2-devel] [PATCH v2 1/1] MdeModulePkg/XhciDxe: Fix
> Broken Timeouts
> 
> Hello Patrick, a couple of inline comments below.
> Hello Ray, need your input on one thing below as well.
> 
> 
> > -----Original Message-----
> > From: devel@edk2.groups.io <devel@edk2.groups.io> On Behalf Of
> > patrick.henz@hpe.com
> > Sent: Thursday, September 3, 2020 1:05 AM
> > To: devel@edk2.groups.io
> > Cc: Patrick Henz <patrick.henz@hpe.com>; Wang, Jian J
> > <jian.j.wang@intel.com>; Wu, Hao A <hao.a.wu@intel.com>; Ni, Ray
> > <ray.ni@intel.com>
> > Subject: [edk2-devel] [PATCH v2 1/1] MdeModulePkg/XhciDxe: Fix Broken
> > Timeouts
> >
> > From: Patrick Henz <patrick.henz@hpe.com>
> >
> > REF:INVALID URI REMOVED
> > ocore.org_show-5Fbug.cgi-3Fid-
> 3D2948&d=DwIFAg&c=C5b8zRQO1miGmBeVZ2LFWg
> >
> &r=wx4n0HbqxSAP19Eklmv6gq7ivDQlqQ_ITOkZIBUNNKg&m=OKlWpRL8ZyDf
> hUEh6S4OU
> > aMasig0MPoajX7Vz2sDSvY&s=LTDbPsspkRCcWFBfThqhR_FaljF2kQLagB_t-
> kbAm80&e
> > =
> >
> > Timeouts in the XhciDxe driver are taking longer than expected due to
> > the timeout loops not accounting for code execution time. As en
> > example, 5 second timeouts have been observed to take around 36
> > seconds to complete.
> > Use SetTimer and Create/CheckEvent from Boot Services to determine
> > when timeout occurred.
> >
> > Cc: Jian J Wang <jian.j.wang@intel.com>
> > Cc: Hao A Wu <hao.a.wu@intel.com>
> > Cc: Ray Ni <ray.ni@intel.com>
> > Signed-off-by: Patrick Henz <patrick.henz@hpe.com>
> > ---
> >  MdeModulePkg/Bus/Pci/XhciDxe/XhciReg.c   | 35 ++++++++++++++++---
> >  MdeModulePkg/Bus/Pci/XhciDxe/XhciSched.c | 43
> > +++++++++++++++++++-----
> >  2 files changed, 65 insertions(+), 13 deletions(-)
> >
> > diff --git a/MdeModulePkg/Bus/Pci/XhciDxe/XhciReg.c
> > b/MdeModulePkg/Bus/Pci/XhciDxe/XhciReg.c
> > index 42b773ab31be..33ac13504669 100644
> > --- a/MdeModulePkg/Bus/Pci/XhciDxe/XhciReg.c
> > +++ b/MdeModulePkg/Bus/Pci/XhciDxe/XhciReg.c
> > @@ -442,17 +442,44 @@ XhcWaitOpRegBit (
> >    IN UINT32               Timeout
> >    )
> >  {
> > -  UINT32                  Index;
> > -  UINT64                  Loop;
> > +  EFI_STATUS Status;
> > +  EFI_EVENT  TimeoutEvent;
> >
> > -  Loop   = Timeout * XHC_1_MILLISECOND;
> > +  TimeoutEvent = NULL;
> >
> > -  for (Index = 0; Index < Loop; Index++) {
> > +  if (Timeout == 0) {
> > +    goto TIMEOUT;
> > +  }
> > +
> > +  Status = gBS->CreateEvent (
> > +                  EVT_TIMER,
> > +                  TPL_CALLBACK,
> > +                  NULL,
> > +                  NULL,
> > +                  &TimeoutEvent
> > +                  );
> > +
> > +  if (!EFI_ERROR (Status)) {
> > +    Status = gBS->SetTimer (TimeoutEvent,
> > +                            TimerRelative,
> > +                            EFI_TIMER_PERIOD_MILLISECONDS(Timeout));
> > +  }
> > +
> > +  if (EFI_ERROR(Status)) {
> > +    goto TIMEOUT;
> > +  }
> 
> 
> Could you help to refine the return status for the case when CreateEvent or
> SetTimer calls fail?
> I think it will return EFI_TIMEOUT at this moment, which might confuse the
> caller.
> You may need to modify the function description comment section for the
> new return value also.
> 
> A similar case applies to XhcExecTransfer() as well.
> 
> 
> > +
> > +  do {
> >      if (XHC_REG_BIT_IS_SET (Xhc, Offset, Bit) == WaitToSet) {
> >        return EFI_SUCCESS;
> >      }
> >
> >      gBS->Stall (XHC_1_MICROSECOND);
> > +  } while (EFI_ERROR(gBS->CheckEvent (TimeoutEvent)));
> > +
> > +TIMEOUT:
> > +  if (TimeoutEvent != NULL) {
> > +    gBS->CloseEvent (TimeoutEvent);
> >    }
> >
> >    return EFI_TIMEOUT;
> > diff --git a/MdeModulePkg/Bus/Pci/XhciDxe/XhciSched.c
> > b/MdeModulePkg/Bus/Pci/XhciDxe/XhciSched.c
> > index ab8957c546ee..d6290b5fe33b 100644
> > --- a/MdeModulePkg/Bus/Pci/XhciDxe/XhciSched.c
> > +++ b/MdeModulePkg/Bus/Pci/XhciDxe/XhciSched.c
> > @@ -1273,11 +1273,19 @@ XhcExecTransfer (
> >    )
> >  {
> >    EFI_STATUS              Status;
> > -  UINTN                   Index;
> > -  UINT64                  Loop;
> >    UINT8                   SlotId;
> >    UINT8                   Dci;
> >    BOOLEAN                 Finished;
> > +  EFI_EVENT               TimeoutEvent;
> > +  EFI_STATUS              TimerStatus;
> > +
> > +  Status       = EFI_SUCCESS;
> > +  Finished     = FALSE;
> > +  TimeoutEvent = NULL;
> > +
> > +  if (Timeout == 0) {
> > +    goto DONE;
> > +  }
> >
> >    if (CmdTransfer) {
> >      SlotId = 0;
> > @@ -1291,29 +1299,46 @@ XhcExecTransfer (
> >      ASSERT (Dci < 32);
> >    }
> >
> > -  Status = EFI_SUCCESS;
> > -  Loop   = Timeout * XHC_1_MILLISECOND;
> > -  if (Timeout == 0) {
> > -    Loop = 0xFFFFFFFF;
> 
> 
> Ray and Patrick, the previous behavior when 'Timeout' is 0 for this function is
> that it will do a 'psudo-indefinite' loop by setting the 'Loop' variable to the
> value of MAX_UINT32.
> 
> But after the patch, the behavior got changed and the function will directly
> return EFI_TIMEOUT when 'Timeout' is 0.
> This behavior change might impact the callers when they expecting a 'psudo-
> indefinite' timeout.
> I think it would be better to keep the origin behavior, what is your thought?
> 
> Best Regards,
> Hao Wu
> 
> 
> > +  TimerStatus = gBS->CreateEvent (
> > +                       EVT_TIMER,
> > +                       TPL_CALLBACK,
> > +                       NULL,
> > +                       NULL,
> > +                       &TimeoutEvent
> > +                       );
> > +
> > +  if (!EFI_ERROR (TimerStatus)) {
> > +    TimerStatus = gBS->SetTimer (TimeoutEvent,
> > +                                 TimerRelative,
> > +
> > + EFI_TIMER_PERIOD_MILLISECONDS(Timeout));
> > +  }
> > +
> > +  if (EFI_ERROR (TimerStatus)) {
> > +    goto DONE;
> >    }
> >
> >    XhcRingDoorBell (Xhc, SlotId, Dci);
> >
> > -  for (Index = 0; Index < Loop; Index++) {
> > +  do {
> >      Finished = XhcCheckUrbResult (Xhc, Urb);
> >      if (Finished) {
> >        break;
> >      }
> >      gBS->Stall (XHC_1_MICROSECOND);
> > -  }
> > +  } while (EFI_ERROR(gBS->CheckEvent (TimeoutEvent)));
> >
> > -  if (Index == Loop) {
> > +DONE:
> > +  if (!Finished) {
> >      Urb->Result = EFI_USB_ERR_TIMEOUT;
> >      Status      = EFI_TIMEOUT;
> >    } else if (Urb->Result != EFI_USB_NOERROR) {
> >      Status      = EFI_DEVICE_ERROR;
> >    }
> >
> > +  if (TimeoutEvent != NULL) {
> > +    gBS->CloseEvent (TimeoutEvent);
> > +  }
> > +
> >    return Status;
> >  }
> >
> > --
> > 2.28.0
> >
> >
> >
> 
> 
> 
> 
> 
>