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[U-Boot,v2,1/5] ARM: pxa: prevent PXA270 occasional reboot freezes

Message ID 1387242224-22495-2-git-send-email-ynvich@gmail.com
State Accepted
Delegated to: Marek Vasut
Headers show

Commit Message

Sergey Yanovich Dec. 17, 2013, 1:03 a.m. UTC 
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.

Signed-off-by: Sergei Ianovich <ynvich@gmail.com>
CC: Marek Vasut <marex@denx.de>
---
 Changes v1..v2
 * write to MDREFR once instead of in a cycle as suggested by
   Marek Vasut

 arch/arm/cpu/pxa/pxa2xx.c | 1 +
 1 file changed, 1 insertion(+)
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Patch

diff --git a/arch/arm/cpu/pxa/pxa2xx.c b/arch/arm/cpu/pxa/pxa2xx.c
index c9a7d45..7e861e2 100644
--- a/arch/arm/cpu/pxa/pxa2xx.c
+++ b/arch/arm/cpu/pxa/pxa2xx.c
@@ -279,6 +279,7 @@  void reset_cpu(ulong ignored)
 	tmp = readl(OSCR);
 	tmp += 0x1000;
 	writel(tmp, OSMR3);
+	writel(MDREFR_SLFRSH, MDREFR);
 
 	for (;;)
 		;