linux-kernel - [PATCH AUTOSEL 4.19 009/205] arm64: dts: allwinner: a64: Olinuxino: fix DRAM voltage

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Date:   Fri,  8 Nov 2019 06:34:36 -0500
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Andre Przywara <andre.przywara@....com>,
        Martin Lucina <martin@...ina.net>,
        Maxime Ripard <maxime.ripard@...tlin.com>,
        Chen-Yu Tsai <wens@...e.org>, Sasha Levin <sashal@...nel.org>,
        devicetree@...r.kernel.org
Subject: [PATCH AUTOSEL 4.19 009/205] arm64: dts: allwinner: a64: Olinuxino: fix DRAM voltage

From: Andre Przywara <andre.przywara@....com>

[ Upstream commit 93366b49a35f3a190052734b3f32c8fe2535b53f ]

The Olinuxino board uses DDR3L chips which are supposed to be driven
with 1.35V. The reset default of the AXP is properly set to 1.36V.

While technically the chips can also run at 1.5 volts, changing the
voltage on the fly while booting Linux is asking for trouble. Also
running at a lower voltage saves power.

So fix the DCDC5 value to match the actual board design.

Signed-off-by: Andre Przywara <andre.przywara@....com>
Tested-by: Martin Lucina <martin@...ina.net>
Acked-by: Maxime Ripard <maxime.ripard@...tlin.com>
Signed-off-by: Chen-Yu Tsai <wens@...e.org>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 arch/arm64/boot/dts/allwinner/sun50i-a64-olinuxino.dts | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/boot/dts/allwinner/sun50i-a64-olinuxino.dts b/arch/arm64/boot/dts/allwinner/sun50i-a64-olinuxino.dts
index 3f531393eaee9..b3f186434f363 100644
--- a/arch/arm64/boot/dts/allwinner/sun50i-a64-olinuxino.dts
+++ b/arch/arm64/boot/dts/allwinner/sun50i-a64-olinuxino.dts
@@ -142,10 +142,14 @@
 
 /* DCDC3 is polyphased with DCDC2 */
 
+/*
+ * The board uses DDR3L DRAM chips. 1.36V is the closest to the nominal
+ * 1.35V that the PMIC can drive.
+ */
 &reg_dcdc5 {
 	regulator-always-on;
-	regulator-min-microvolt = <1500000>;
-	regulator-max-microvolt = <1500000>;
+	regulator-min-microvolt = <1360000>;
+	regulator-max-microvolt = <1360000>;
 	regulator-name = "vcc-ddr3";
 };
 
-- 
2.20.1