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authorSergei Ianovich <ynvich@gmail.com>2013-12-10 08:39:15 +0400
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2013-12-20 07:45:07 -0800
commitff1dbcb8f938b2344b0d4c37c83ee75d360157cf (patch)
tree9e19028cd6e26bf5c4f1e5a1ae45134d6256b85b
parent886a5c50e528c5190f88d6e9fa88d612257dad18 (diff)
ARM: pxa: prevent PXA270 occasional reboot freezes
commit ff88b4724fde18056a4c539f7327389aec0f4c2d upstream. 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> Tested-by: Marek Vasut <marex@denx.de> Signed-off-by: Haojian Zhuang <haojian.zhuang@gmail.com> Signed-off-by: Olof Johansson <olof@lixom.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--arch/arm/mach-pxa/reset.c8
1 files changed, 7 insertions, 1 deletions
diff --git a/arch/arm/mach-pxa/reset.c b/arch/arm/mach-pxa/reset.c
index 3fab583755d4..0616390b857f 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(char mode, const char *cmd)
@@ -104,4 +111,3 @@ void pxa_restart(char mode, const char *cmd)
break;
}
}
-