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From 662134c1007cc275193737dd11ea4b77f47256a7 Mon Sep 17 00:00:00 2001
From: AnilKumar Ch <anilkumar@ti.com>
Date: Tue, 26 Jun 2012 15:41:51 +0530
Subject: [PATCH 79/79] AM335X: errata: OPP50 on MPU domain is not supported
This patch implements a workaround for OPP50 erratum, Advisory
1.0.15 at http://www.ti.com/lit/er/sprz360b/sprz360b.pdf
OPP50 Operation on MPU Domain is Not Supported. This issue seen with
reliability tests running on MPU. To minimize power consumption, the
ARM Cortex-A8 may be operated at the lower frequency defined by OPP50,
but the respective power terminal VDD_MPU must be operated as defined
by OPP100. So MPU OPP50 modified to <275MHz, 1.1V>.
Power consumption as seen on AM335x EVM:
OPP50 <275MHz, 0.95> - 40.5 mW
OPP50 <275MHz, 1.10> - 55.5 mW
OPP100 <500MHz, 1.10> - 98.5 mW
Based on the above data we can see 43mW power savings compared to
OPP100. This is the reason for keeping OPP50 alive instead of
shutting down completely.
Signed-off-by: AnilKumar Ch <anilkumar@ti.com>
---
arch/arm/mach-omap2/opp3xxx_data.c | 10 +++++++++-
1 file changed, 9 insertions(+), 1 deletion(-)
diff --git a/arch/arm/mach-omap2/opp3xxx_data.c b/arch/arm/mach-omap2/opp3xxx_data.c
index 0e540c8..9fbcfc3 100644
--- a/arch/arm/mach-omap2/opp3xxx_data.c
+++ b/arch/arm/mach-omap2/opp3xxx_data.c
@@ -154,7 +154,15 @@ static struct omap_opp_def __initdata omap36xx_opp_def_list[] = {
/* VDD1 */
-#define AM33XX_VDD_MPU_OPP50_UV 950000
+/*
+ * Errata 1.0.15: OPP50 Operation on MPU Domain is Not Supported.
+ *
+ * To minimize power consumption, the ARM Cortex-A8 may be operated at
+ * the lower frequency defined by OPP50, but the respective voltage
+ * domain VDD_MPU must be operated as defined by OPP100. So MPU OPP50
+ * definition is modified to 275MHz, 1.1V.
+ */
+#define AM33XX_VDD_MPU_OPP50_UV 1100000
#define AM33XX_VDD_MPU_OPP100_UV 1100000
#define AM33XX_VDD_MPU_OPP120_UV 1200000
#define AM33XX_VDD_MPU_OPPTURBO_UV 1260000
--
1.7.10
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