Re: [PATCH v2 03/28] Silicon/NXP/I2cDxe: Fix I2c Timeout with RTC

["Leif Lindholm" <leif@nuviainc.com>]

On Fri, Mar 20, 2020 at 20:05:18 +0530, Pankaj Bansal wrote:
> From: Pankaj Bansal <pankaj.bansal@nxp.com>
> 
> With latest edk2 codebase, sometimes i2c timeout is observed when
> Network devices are being probed.
> This is happening when gRT->GetTime request is ongoing.
> gRT->GetTime triggers a read request to Real Time Clock which is
> connected to I2c bus.
> In between read request, if an event occurs, which also triggers
> gRT->GetTime (i.e. RTC read), the I2c bus goes into unrecovered state.
> 
> This state is not even recovered, when rebooting the board.
> We need to power off the board completely to recover i2c bus.
> 
> To prevent this, TPL level of I2c read is being raised to high, so that
> no other event can preempt this. with this solution no timeout has been
> observed so far.
> 
> Signed-off-by: Pankaj Bansal <pankaj.bansal@nxp.com>

Reviewed-by: Leif Lindholm <leif@nuviainc.com>

> ---
>  Silicon/NXP/Drivers/I2cDxe/I2cDxe.c   | 12 ++++++++++++
>  Silicon/NXP/Drivers/I2cDxe/I2cDxe.inf |  3 ++-
>  2 files changed, 14 insertions(+), 1 deletion(-)
> 
> diff --git a/Silicon/NXP/Drivers/I2cDxe/I2cDxe.c b/Silicon/NXP/Drivers/I2cDxe/I2cDxe.c
> index 848e707c1673..a5aba47b3ed4 100644
> --- a/Silicon/NXP/Drivers/I2cDxe/I2cDxe.c
> +++ b/Silicon/NXP/Drivers/I2cDxe/I2cDxe.c
> @@ -16,6 +16,7 @@
>  #include <Library/TimerLib.h>
>  #include <Library/UefiBootServicesTableLib.h>
>  #include <Library/UefiLib.h>
> +#include <Library/UefiRuntimeLib.h>
>  
>  #include "I2cDxe.h"
>  
> @@ -88,6 +89,13 @@ StartRequest (
>    NXP_I2C_MASTER           *I2c;
>    UINTN                    I2cBase;
>    EFI_STATUS               Status;
> +  EFI_TPL                  Tpl;
> +  BOOLEAN                  AtRuntime;
> +
> +  AtRuntime = EfiAtRuntime ();
> +  if (!AtRuntime) {
> +    Tpl = gBS->RaiseTPL (TPL_HIGH_LEVEL);
> +  }
>  
>    I2c = NXP_I2C_FROM_THIS (This);
>  
> @@ -95,6 +103,10 @@ StartRequest (
>  
>    Status = I2cBusXfer (I2cBase, SlaveAddress, RequestPacket);
>  
> +  if (!AtRuntime) {
> +    gBS->RestoreTPL (Tpl);
> +  }
> +
>    return Status;
>  }
>  
> diff --git a/Silicon/NXP/Drivers/I2cDxe/I2cDxe.inf b/Silicon/NXP/Drivers/I2cDxe/I2cDxe.inf
> index 84adb837c249..867376044656 100644
> --- a/Silicon/NXP/Drivers/I2cDxe/I2cDxe.inf
> +++ b/Silicon/NXP/Drivers/I2cDxe/I2cDxe.inf
> @@ -13,7 +13,7 @@ [Defines]
>    INF_VERSION                    = 0x0001001A
>    BASE_NAME                      = I2cDxe
>    FILE_GUID                      = 5f2927ba-1b04-4d5f-8bef-2b50c635d1e7
> -  MODULE_TYPE                    = DXE_DRIVER
> +  MODULE_TYPE                    = DXE_RUNTIME_DRIVER
>    VERSION_STRING                 = 1.0
>    ENTRY_POINT                    = I2cDxeEntryPoint
>    UNLOAD                         = I2cDxeUnload
> @@ -36,6 +36,7 @@ [LibraryClasses]
>    UefiBootServicesTableLib
>    UefiDriverEntryPoint
>    UefiLib
> +  UefiRuntimeLib
>  
>  [Guids]
>    gNxpNonDiscoverableI2cMasterGuid
> -- 
> 2.17.1
>