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

[haojian.zhuang@gmail.com (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@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
>

Applied.

Thanks
Haojian