[U-Boot] [PATCH 1/4] ARM: pxa: prevent PXA270 occasional reboot freezes

[Marek Vasut]

On Saturday, December 14, 2013 at 06:41:57 AM, Sergei Ianovich wrote:
> Erratum 71 of PXA270M Processor Family Specification Update
> (April 19, 2010) explains that watchdog reset time is just
> 8us insead of 10ms in EMTS.
> 
> If SDRAM is not reset, it causes memory bus congestion and
> the device hangs.
> 
> We put SDRAM in selfresh mode before watchdog reset, removing
> potential freezes.
> 
> Signed-off-by: Sergei Ianovich <ynvich at gmail.com>
> ---
>  arch/arm/cpu/pxa/pxa2xx.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/arm/cpu/pxa/pxa2xx.c b/arch/arm/cpu/pxa/pxa2xx.c
> index c9a7d45..93ca2f0 100644
> --- a/arch/arm/cpu/pxa/pxa2xx.c
> +++ b/arch/arm/cpu/pxa/pxa2xx.c
> @@ -281,5 +281,5 @@ void reset_cpu(ulong ignored)
>  	writel(tmp, OSMR3);
> 
>  	for (;;)
> -		;
> +		writel(MDREFR_SLFRSH, MDREFR);

Do you need to write this register in an endless loop ?

>  }

Best regards,
Marek Vasut