From mboxrd@z Thu Jan 1 00:00:00 1970 From: andre.przywara@arm.com (Andre Przywara) Date: Fri, 6 Jul 2018 10:05:32 +0100 Subject: [linux-sunxi] [PATCH 03/10] arm64: dts: allwinner: a64: Olinuxino: fix DRAM voltage In-Reply-To: <859578FF-AB96-4B51-8E7E-2F144E35C47A@aosc.io> References: <20180706085210.17952-1-andre.przywara@arm.com> <20180706085210.17952-4-andre.przywara@arm.com> <859578FF-AB96-4B51-8E7E-2F144E35C47A@aosc.io> Message-ID: To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org Hi, On 06/07/18 09:55, Icenowy Zheng wrote: > > > ? 2018?7?6? GMT+08:00 ??4:52:03, Andre Przywara ??: >> 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 >> --- >> arch/arm64/boot/dts/allwinner/sun50i-a64-olinuxino.dts | 10 ++++++---- >> 1 file changed, 6 insertions(+), 4 deletions(-) >> >> diff --git a/arch/arm64/boot/dts/allwinner/sun50i-a64-olinuxino.dts >> b/arch/arm64/boot/dts/allwinner/sun50i-a64-olinuxino.dts >> index 3f531393eaee..f945c70f3a80 100644 >> --- a/arch/arm64/boot/dts/allwinner/sun50i-a64-olinuxino.dts >> +++ b/arch/arm64/boot/dts/allwinner/sun50i-a64-olinuxino.dts >> @@ -140,12 +140,14 @@ >> regulator-name = "vdd-cpux"; >> }; >> >> -/* DCDC3 is polyphased with DCDC2 */ >> - >> +/* >> + * DCDC3 is polyphased with DCDC2 to supply the DDR3L DRAM chips. >> + * 1.36V is the closest to the nominal 1.35V that the PMIC can drive. > > The comment is a mess. DCDC2+3 is for CPU, and 5 is for DRAM. Aargh, true. I was misled by that lonely comment. > Personally I suggest to use two comment blocks, one sit at > where dcdc3 should appear, and the second before dcdc5. Yeah, sounds like the right thing to do. Thanks for having a look! Cheers, Andre. >> + */ >> ®_dcdc5 { >> regulator-always-on; >> - regulator-min-microvolt = <1500000>; >> - regulator-max-microvolt = <1500000>; >> + regulator-min-microvolt = <1360000>; >> + regulator-max-microvolt = <1360000>; >> regulator-name = "vcc-ddr3"; >> }; >>