From 75f251e3d0803b028f3474fdc75be0994c377ab5 Mon Sep 17 00:00:00 2001
From: Paul Walmsley <paul@pwsan.com>
Date: Fri, 24 Jul 2009 19:44:01 -0600
Subject: OMAP2/3 SDRC: don't set SDRC_POWER.PWDENA on boot

Stop setting SDRC_POWER.PWDENA on boot.  There is a nasty erratum
(34xx erratum 1.150) that can cause memory corruption if PWDENA is
enabled.

Based originally on a patch from Samu P. Onkalo <samu.p.onkalo@nokia.com>.

Tested on BeagleBoard rev C2.

Signed-off-by: Paul Walmsley <paul@pwsan.com>
Cc: Samu P. Onkalo <samu.p.onkalo@nokia.com>
---
 arch/arm/mach-omap2/sdrc.c     | 5 ++++-
 arch/arm/mach-omap2/sram34xx.S | 2 --
 2 files changed, 4 insertions(+), 3 deletions(-)

(limited to 'arch/arm')

diff --git a/arch/arm/mach-omap2/sdrc.c b/arch/arm/mach-omap2/sdrc.c
index 2e9e38db30e..9e3bd4fa781 100644
--- a/arch/arm/mach-omap2/sdrc.c
+++ b/arch/arm/mach-omap2/sdrc.c
@@ -125,8 +125,11 @@ void __init omap2_sdrc_init(struct omap_sdrc_params *sdrc_cs0,
 	sdrc_init_params_cs1 = sdrc_cs1;
 
 	/* XXX Enable SRFRONIDLEREQ here also? */
+	/*
+	 * PWDENA should not be set due to 34xx erratum 1.150 - PWDENA
+	 * can cause random memory corruption
+	 */
 	l = (1 << SDRC_POWER_EXTCLKDIS_SHIFT) |
-		(1 << SDRC_POWER_PWDENA_SHIFT) |
 		(1 << SDRC_POWER_PAGEPOLICY_SHIFT);
 	sdrc_write_reg(l, SDRC_POWER);
 }
diff --git a/arch/arm/mach-omap2/sram34xx.S b/arch/arm/mach-omap2/sram34xx.S
index 3aef7448b2a..9c2d0465a83 100644
--- a/arch/arm/mach-omap2/sram34xx.S
+++ b/arch/arm/mach-omap2/sram34xx.S
@@ -58,7 +58,6 @@
 
 /* SDRC_POWER bit settings */
 #define SRFRONIDLEREQ_MASK		0x40
-#define PWDENA_MASK			0x4
 
 /* CM_IDLEST1_CORE bit settings */
 #define ST_SDRC_MASK			0x2
@@ -160,7 +159,6 @@ sdram_in_selfrefresh:
 	ldr	r12, [r11]		@ read the contents of SDRC_POWER
 	mov	r9, r12			@ keep a copy of SDRC_POWER bits
 	orr 	r12, r12, #SRFRONIDLEREQ_MASK	@ enable self refresh on idle
-	bic 	r12, r12, #PWDENA_MASK	@ clear PWDENA
 	str 	r12, [r11]		@ write back to SDRC_POWER register
 	ldr	r12, [r11]		@ posted-write barrier for SDRC
 idle_sdrc:
-- 
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