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SubjectRe: [PATCH] ARM: pxa: prevent PXA270 occasional reboot freezes
Date
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@gmail.com>
> >> ---
> >>
> >> 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@denx.de>

Best regards,
Marek Vasut


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