linux-kernel - [PATCH] MIPS: DTS: CI20: Raise VDDCORE voltage to 1.125 volts

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Date:   Thu, 22 Jun 2023 19:59:34 +0200
From:   Paul Cercueil <paul@...pouillou.net>
To:     Thomas Bogendoerfer <tsbogend@...ha.franken.de>
Cc:     Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Conor Dooley <conor+dt@...nel.org>, linux-mips@...r.kernel.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        list@...ndingux.net, Paul Cercueil <paul@...pouillou.net>,
        "H . Nikolaus Schaller" <hns@...delico.com>
Subject: [PATCH] MIPS: DTS: CI20: Raise VDDCORE voltage to 1.125 volts

Commit 08384e80a70f ("MIPS: DTS: CI20: Fix ACT8600 regulator node
names") caused the VDDCORE power supply (regulated by the ACT8600's
DCDC1 output) to drop from a voltage of 1.2V configured by the
bootloader, to the 1.1V set in the Device Tree.

According to the documentation, the VDDCORE supply should be between
0.99V and 1.21V; both values are therefore within the supported range.

However, VDDCORE being 1.1V results in the CI20 being very unstable,
with corrupted memory, failures to boot, or reboots at random. The
reason might be succint drops of the voltage below the minimum required.

Raising the minimum voltage to 1.125 volts seems to be enough to address
this issue, while still keeping a relatively low core voltage which
helps for power consumption and thermals.

Fixes: 08384e80a70f ("MIPS: DTS: CI20: Fix ACT8600 regulator node names")
Signed-off-by: Paul Cercueil <paul@...pouillou.net>

---
Cc: H. Nikolaus Schaller <hns@...delico.com>
---
 arch/mips/boot/dts/ingenic/ci20.dts | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/mips/boot/dts/ingenic/ci20.dts b/arch/mips/boot/dts/ingenic/ci20.dts
index cec0caa2350c..a141a699b790 100644
--- a/arch/mips/boot/dts/ingenic/ci20.dts
+++ b/arch/mips/boot/dts/ingenic/ci20.dts
@@ -298,8 +298,8 @@ act8600: act8600@5a {

 		regulators {
 			vddcore: DCDC1 {
-				regulator-min-microvolt = <1100000>;
-				regulator-max-microvolt = <1100000>;
+				regulator-min-microvolt = <1125000>;
+				regulator-max-microvolt = <1125000>;
 				vp1-supply = <&vcc_33v>;
 				regulator-always-on;
 			};
-- 
2.40.1