linux-kernel - [PATCH] ARM: davinci: turn off DDR PHY when entering deep sleep

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Date:	Thu, 10 May 2012 19:52:32 +0200
From:	Marcus Folkesson <marcus.folkesson@...il.com>
To:	Sekhar Nori <nsekhar@...com>, Kevin Hilman <khilman@...com>,
	Russell King <linux@....linux.org.uk>,
	Nicolas Pitre <nicolas.pitre@...aro.org>,
	Catalin Marinas <catalin.marinas@....com>,
	Marcus Folkesson <marcus.folkesson@...il.com>,
	linux-arm-kernel@...ts.infradead.org
Cc:	linux-kernel@...r.kernel.org
Subject: [PATCH] ARM: davinci: turn off DDR PHY when entering deep sleep

Deepsleep is the most power saving state on the davinci-platform.
The DDR PHY consumes about 25mW and should be turned off in this low
power state.

Signed-off-by: Marcus Folkesson <marcus.folkesson@...il.com>
---
 arch/arm/mach-davinci/include/mach/memory.h |    2 ++
 arch/arm/mach-davinci/sleep.S               |   10 ++++++++++
 2 files changed, 12 insertions(+), 0 deletions(-)

diff --git a/arch/arm/mach-davinci/include/mach/memory.h b/arch/arm/mach-davinci/include/mach/memory.h
index 7873194..1b1b8ac 100644
--- a/arch/arm/mach-davinci/include/mach/memory.h
+++ b/arch/arm/mach-davinci/include/mach/memory.h
@@ -36,6 +36,8 @@
 #define DDR2_MCLKSTOPEN_BIT	BIT(30)
 #define DDR2_LPMODEN_BIT	BIT(31)
 
+#define DDR2_DRPHYC1R_OFFSET 	0xe4
+#define DDR_PWRDNEN_BIT 		BIT(6)
 /*
  * Increase size of DMA-consistent memory region
  */
diff --git a/arch/arm/mach-davinci/sleep.S b/arch/arm/mach-davinci/sleep.S
index 5f1e045..30713b2 100644
--- a/arch/arm/mach-davinci/sleep.S
+++ b/arch/arm/mach-davinci/sleep.S
@@ -57,6 +57,11 @@ ENTRY(davinci_cpu_suspend)
 
 	ldmia	r0, {r0-r4}
 
+	/* Turn PHY off */
+	ldr	ip, [r0, #DDR2_DRPHYC1R_OFFSET]
+	orr	ip, ip, #DDR_PWRDNEN_BIT 	
+	str	ip, [r0, #DDR2_DRPHYC1R_OFFSET]
+
 	/*
 	 * Switch DDR to self-refresh mode.
 	 */
@@ -171,6 +176,11 @@ ENTRY(davinci_cpu_suspend)
 	bic	ip, ip, #DDR2_LPMODEN_BIT
 	str	ip, [r0, #DDR2_SDRCR_OFFSET]
 
+	/* Turn PHY on */
+	ldr	ip, [r0, #DDR2_DRPHYC1R_OFFSET]
+	bic	ip, ip, #DDR_PWRDNEN_BIT 	
+	str	ip, [r0, #DDR2_DRPHYC1R_OFFSET]
+
 	/* Restore registers and return */
 	ldmfd   sp!, {r0-r12, pc}
 
-- 
1.7.5.4

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