Re: [PATCH] ARM: pxa: prevent PXA270 occasional reboot freezes

[Haojian Zhuang]

On 12/11/2013 02:31 AM, Marek Vasut wrote:
> On Tuesday, December 10, 2013 at 11:48:59 AM, Daniel Mack wrote:
> > On 12/10/2013 09:43 AM, Haojian Zhuang wrote:
> > > On 12/10/2013 12:39 PM, 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.
> > > >
> > > > Without this patch PXA270-based ICP DAS LP-8x4x hangs after up to 40
> > > > reboots. With this patch it has successfully rebooted 500 times.
> > > >
> > > > Signed-off-by: Sergei Ianovich <ynvich@xxxxxxxxx>
> > > > ---
> > > >
> > > >    arch/arm/mach-pxa/reset.c | 8 +++++++-
> > > >    1 file changed, 7 insertions(+), 1 deletion(-)
> > > >
> > > > diff --git a/arch/arm/mach-pxa/reset.c b/arch/arm/mach-pxa/reset.c
> > > > index 0d5dd64..263b152 100644
> > > > --- a/arch/arm/mach-pxa/reset.c
> > > > +++ b/arch/arm/mach-pxa/reset.c
> > > > @@ -13,6 +13,7 @@
> > > >
> > > >    #include <mach/regs-ost.h>
> > > >    #include <mach/reset.h>
> > > >
> > > > +#include <mach/smemc.h>
> > > >
> > > >    unsigned int reset_status;
> > > >    EXPORT_SYMBOL(reset_status);
> > > >
> > > > @@ -81,6 +82,12 @@ static void do_hw_reset(void)
> > > >
> > > >    	writel_relaxed(OSSR_M3, OSSR);
> > > >    	/* ... in 100 ms */
> > > >    	writel_relaxed(readl_relaxed(OSCR) + 368640, OSMR3);
> > > >
> > > > +	/*
> > > > +	 * SDRAM hangs on watchdog reset on Marvell PXA270 (erratum 71)
> > > > +	 * we put SDRAM into self-refresh to prevent that
> > > > +	 */
> > > > +	while (1)
> > > > +		writel_relaxed(MDREFR_SLFRSH, MDREFR);
> > > >
> > > >    }
> > > >
> > > >    void pxa_restart(enum reboot_mode mode, const char *cmd)
> > > >
> > > > @@ -104,4 +111,3 @@ void pxa_restart(enum reboot_mode mode, const char
> > > > *cmd)
> > > >
> > > >    		break;
> > > >    	
> > > >    	}
> > > >
> > > >    }
> > > >
> > > > -
> > >
> > > Hi Daniel/Marek/Igor,
> > >
> > > Could you help to try this patch? I'm lack of PXA27x board.
> >
> > I don't have any either right now ...
>
> On VPAC270
>
> Tested-by: Marek Vasut <marex@xxxxxxx>
>
> Best regards,
> Marek Vasut

Applied.

Thanks
Haojian
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