From ff88b4724fde18056a4c539f7327389aec0f4c2d Mon Sep 17 00:00:00 2001 From: Sergei Ianovich Date: Tue, 10 Dec 2013 08:39:15 +0400 Subject: ARM: pxa: prevent PXA270 occasional reboot freezes 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 Tested-by: Marek Vasut Signed-off-by: Haojian Zhuang Cc: stable@vger.kernel.org Signed-off-by: Olof Johansson --- 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 0d5dd646f61f..263b15249b5b 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; } } - -- cgit v1.2.3