Re: [edk2-devel] [PATCH v3 1/1] MdeModulePkg/XhciDxe: Fix Broken Timeouts

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

Reviewed-by: Hao A Wu <hao.a.wu@intel.com>

Best Regards,
Hao Wu

> -----Original Message-----
> From: devel@edk2.groups.io <devel@edk2.groups.io> On Behalf Of Henz,
> Patrick
> Sent: Thursday, September 24, 2020 3:36 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 v3 1/1] MdeModulePkg/XhciDxe: Fix Broken
> Timeouts
> 
> From: Patrick Henz <patrick.henz@hpe.com>
> 
> REF:https://bugzilla.tianocore.org/show_bug.cgi?id=2948
> 
> 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   | 59 +++++++++++++++++-----
>  MdeModulePkg/Bus/Pci/XhciDxe/XhciSched.c | 63 ++++++++++++++++++--
> ----
>  2 files changed, 94 insertions(+), 28 deletions(-)
> 
> diff --git a/MdeModulePkg/Bus/Pci/XhciDxe/XhciReg.c
> b/MdeModulePkg/Bus/Pci/XhciDxe/XhciReg.c
> index 42b773ab31be..2bab09415b28 100644
> --- a/MdeModulePkg/Bus/Pci/XhciDxe/XhciReg.c
> +++ b/MdeModulePkg/Bus/Pci/XhciDxe/XhciReg.c
> @@ -423,14 +423,15 @@ XhcClearOpRegBit (
>    Wait the operation register's bit as specified by Bit
>    to become set (or clear).
> 
> -  @param  Xhc          The XHCI Instance.
> -  @param  Offset       The offset of the operation register.
> -  @param  Bit          The bit of the register to wait for.
> -  @param  WaitToSet    Wait the bit to set or clear.
> -  @param  Timeout      The time to wait before abort (in millisecond, ms).
> +  @param  Xhc                    The XHCI Instance.
> +  @param  Offset                 The offset of the operation register.
> +  @param  Bit                    The bit of the register to wait for.
> +  @param  WaitToSet              Wait the bit to set or clear.
> +  @param  Timeout                The time to wait before abort (in millisecond,
> ms).
> 
> -  @retval EFI_SUCCESS  The bit successfully changed by host controller.
> -  @retval EFI_TIMEOUT  The time out occurred.
> +  @retval EFI_SUCCESS            The bit successfully changed by host controller.
> +  @retval EFI_TIMEOUT            The time out occurred.
> +  @retval EFI_OUT_OF_RESOURCES   Memory for the timer event could not
> be allocated.
> 
>  **/
>  EFI_STATUS
> @@ -442,20 +443,52 @@ 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) {
> +    return EFI_TIMEOUT;
> +  }
> +
> +  Status = gBS->CreateEvent (
> +                  EVT_TIMER,
> +                  TPL_CALLBACK,
> +                  NULL,
> +                  NULL,
> +                  &TimeoutEvent
> +                  );
> +
> +  if (EFI_ERROR(Status)) {
> +    goto DONE;
> +  }
> +
> +  Status = gBS->SetTimer (TimeoutEvent,
> +                          TimerRelative,
> +                          EFI_TIMER_PERIOD_MILLISECONDS(Timeout));
> +
> +  if (EFI_ERROR(Status)) {
> +    goto DONE;
> +  }
> +
> +  do {
>      if (XHC_REG_BIT_IS_SET (Xhc, Offset, Bit) == WaitToSet) {
> -      return EFI_SUCCESS;
> +      Status = EFI_SUCCESS;
> +      goto DONE;
>      }
> 
>      gBS->Stall (XHC_1_MICROSECOND);
> +  } while (EFI_ERROR(gBS->CheckEvent (TimeoutEvent)));
> +
> +  Status = EFI_TIMEOUT;
> +
> +DONE:
> +  if (TimeoutEvent != NULL) {
> +    gBS->CloseEvent (TimeoutEvent);
>    }
> 
> -  return EFI_TIMEOUT;
> +  return Status;
>  }
> 
>  /**
> diff --git a/MdeModulePkg/Bus/Pci/XhciDxe/XhciSched.c
> b/MdeModulePkg/Bus/Pci/XhciDxe/XhciSched.c
> index ab8957c546ee..9cb115363c8b 100644
> --- a/MdeModulePkg/Bus/Pci/XhciDxe/XhciSched.c
> +++ b/MdeModulePkg/Bus/Pci/XhciDxe/XhciSched.c
> @@ -1254,14 +1254,15 @@ XhcCheckUrbResult (
>  /**
>    Execute the transfer by polling the URB. This is a synchronous operation.
> 
> -  @param  Xhc               The XHCI Instance.
> -  @param  CmdTransfer       The executed URB is for cmd transfer or not.
> -  @param  Urb               The URB to execute.
> -  @param  Timeout           The time to wait before abort, in millisecond.
> +  @param  Xhc                    The XHCI Instance.
> +  @param  CmdTransfer            The executed URB is for cmd transfer or not.
> +  @param  Urb                    The URB to execute.
> +  @param  Timeout                The time to wait before abort, in millisecond.
> 
> -  @return EFI_DEVICE_ERROR  The transfer failed due to transfer error.
> -  @return EFI_TIMEOUT       The transfer failed due to time out.
> -  @return EFI_SUCCESS       The transfer finished OK.
> +  @return EFI_DEVICE_ERROR       The transfer failed due to transfer error.
> +  @return EFI_TIMEOUT            The transfer failed due to time out.
> +  @return EFI_SUCCESS            The transfer finished OK.
> +  @retval EFI_OUT_OF_RESOURCES   Memory for the timer event could not
> be allocated.
> 
>  **/
>  EFI_STATUS
> @@ -1273,11 +1274,16 @@ XhcExecTransfer (
>    )
>  {
>    EFI_STATUS              Status;
> -  UINTN                   Index;
> -  UINT64                  Loop;
>    UINT8                   SlotId;
>    UINT8                   Dci;
>    BOOLEAN                 Finished;
> +  EFI_EVENT               TimeoutEvent;
> +  BOOLEAN                 IndefiniteTimeout;
> +
> +  Status            = EFI_SUCCESS;
> +  Finished          = FALSE;
> +  TimeoutEvent      = NULL;
> +  IndefiniteTimeout = FALSE;
> 
>    if (CmdTransfer) {
>      SlotId = 0;
> @@ -1291,29 +1297,56 @@ XhcExecTransfer (
>      ASSERT (Dci < 32);
>    }
> 
> -  Status = EFI_SUCCESS;
> -  Loop   = Timeout * XHC_1_MILLISECOND;
>    if (Timeout == 0) {
> -    Loop = 0xFFFFFFFF;
> +    IndefiniteTimeout = TRUE;
> +    goto RINGDOORBELL;
>    }
> 
> +  Status = gBS->CreateEvent (
> +                  EVT_TIMER,
> +                  TPL_CALLBACK,
> +                  NULL,
> +                  NULL,
> +                  &TimeoutEvent
> +                  );
> +
> +  if (EFI_ERROR (Status)) {
> +    goto DONE;
> +  }
> +
> +  Status = gBS->SetTimer (TimeoutEvent,
> +                          TimerRelative,
> +                          EFI_TIMER_PERIOD_MILLISECONDS(Timeout));
> +
> +  if (EFI_ERROR (Status)) {
> +    goto DONE;
> +  }
> +
> +RINGDOORBELL:
>    XhcRingDoorBell (Xhc, SlotId, Dci);
> 
> -  for (Index = 0; Index < Loop; Index++) {
> +  do {
>      Finished = XhcCheckUrbResult (Xhc, Urb);
>      if (Finished) {
>        break;
>      }
>      gBS->Stall (XHC_1_MICROSECOND);
> -  }
> +  } while (IndefiniteTimeout || EFI_ERROR(gBS->CheckEvent
> + (TimeoutEvent)));
> 
> -  if (Index == Loop) {
> +DONE:
> +  if (EFI_ERROR(Status)) {
> +    Urb->Result = EFI_USB_ERR_NOTEXECUTE;
> +  } else 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
> 
> 
> 
> 
>