arm64: dts: allwinner: a64: Olinuxino: fix DRAM voltage

[ Upstream commit 93366b49 ]

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@arm.com>
Tested-by: Martin Lucina <martin@lucina.net>
Acked-by: Maxime Ripard <maxime.ripard@bootlin.com>
Signed-off-by: Chen-Yu Tsai <wens@csie.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

arch/arm64/boot/dts/allwinner/sun50i-a64-olinuxino.dts

@@ -142,10 +142,14 @@ &reg_dcdc2 {
 
 /* 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";
 };