From mboxrd@z Thu Jan 1 00:00:00 1970 From: haojian.zhuang@gmail.com (Haojian Zhuang) Date: Tue, 10 Dec 2013 16:43:56 +0800 Subject: [PATCH] ARM: pxa: prevent PXA270 occasional reboot freezes In-Reply-To: <1386650355-2503-1-git-send-email-ynvich@gmail.com> References: <1386650355-2503-1-git-send-email-ynvich@gmail.com> Message-ID: <52A6D44C.1010504@gmail.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org 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 > --- > 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 > #include > +#include > > 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. Best Regards Haojian