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

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Date:	Tue, 10 Dec 2013 11:48:59 +0100
From:	Daniel Mack <zonque@...il.com>
To:	Haojian Zhuang <haojian.zhuang@...il.com>,
	Sergei Ianovich <ynvich@...il.com>,
	linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org
CC:	Eric Miao <eric.y.miao@...il.com>,
	Russell King <linux@....linux.org.uk>,
	Marek Vasut <marex@...x.de>,
	Igor Grinberg <grinberg@...pulab.co.il>
Subject: Re: [PATCH] ARM: pxa: prevent PXA270 occasional reboot freezes

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@...il.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 ...


Daniel

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