Re: [PATCH] ArmPkg/GenericWatchdogDxe: Split 64bit register write to 2x32bit

[Ard Biesheuvel <ard.biesheuvel@linaro.org>]

On 2 August 2018 at 16:49, Marcin Wojtas <mw@semihalf.com> wrote:
> EDK2 code uses a single 64bit write to update SBSA watchdog
> compare registers, however an access to mmio registers should
> be 32bit for some SoCs. Current usage of MmioWrite64 resulted
> in an unpredicted behavior. Fix this by modifying
> WatchdogWriteCompareRegister routine to use two consecutive
> 32bit writes to Watchdog Compare Register Low and High.
>

You describe it as if this is generally the case, but this is just a
silicon bug, right?

> Contributed-under: TianoCore Contribution Agreement 1.1
> Signed-off-by: Marcin Wojtas <mw@semihalf.com>
> ---
>  ArmPkg/Drivers/GenericWatchdogDxe/GenericWatchdogDxe.c | 6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
>
> diff --git a/ArmPkg/Drivers/GenericWatchdogDxe/GenericWatchdogDxe.c b/ArmPkg/Drivers/GenericWatchdogDxe/GenericWatchdogDxe.c
> index 3180f01..b25d210 100644
> --- a/ArmPkg/Drivers/GenericWatchdogDxe/GenericWatchdogDxe.c
> +++ b/ArmPkg/Drivers/GenericWatchdogDxe/GenericWatchdogDxe.c
> @@ -56,7 +56,11 @@ WatchdogWriteCompareRegister (
>    UINT64  Value
>    )
>  {
> -  MmioWrite64 (GENERIC_WDOG_COMPARE_VALUE_REG, Value);
> +  MmioWrite32 (GENERIC_WDOG_COMPARE_VALUE_REG, Value & MAX_UINT32);
> +  MmioWrite32 (
> +    GENERIC_WDOG_COMPARE_VALUE_REG + sizeof (UINT32),
> +    (Value >> 32) & MAX_UINT32
> +    );
>  }
>
>  VOID
> --
> 2.7.4
>