arm64: dts: apq8096-db820c: Fix VDD core voltage

APQ8096 has its VDD APC (Power for quad Kryo applications
microprocessors) powered by PM8996 PMIC S9, S10, S11 tri-phase
regulators (gang). The bootloader may have configured these
regulators with non sustainable default values, leading to sporadic
hangs under CPU stress tests (cpufreq-bench). Ideally we should enable
voltage scaling along with frequency scaling, but for now just set the
regulator gang value to a sane voltage, capable of supporting highest
frequencies (turbo).

Signed-off-by: Loic Poulain <loic.poulain@linaro.org>
Link: https://lore.kernel.org/r/1578401755-26211-1-git-send-email-loic.poulain@linaro.org
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>

arch/arm64/boot/dts/qcom/apq8096-db820c.dtsi

@@ -647,6 +647,22 @@
 		"NC";
 };
 
+&pm8994_spmi_regulators {
+	qcom,saw-reg = <&saw3>;
+	s9 {
+		qcom,saw-slave;
+	};
+	s10 {
+		qcom,saw-slave;
+	};
+	s11 {
+		qcom,saw-leader;
+		regulator-always-on;
+		regulator-min-microvolt = <1230000>;
+		regulator-max-microvolt = <1230000>;
+	};
+};
+
 &pmi8994_gpios {
 	gpio-line-names =
 		"NC",

arch/arm64/boot/dts/qcom/msm8996.dtsi

@@ -2137,6 +2137,11 @@
 			};
 		};
 
+		saw3: syscon@9a10000 {
+			compatible = "syscon";
+			reg = <0x09a10000 0x1000>;
+		};
+
 		intc: interrupt-controller@9bc0000 {
 			compatible = "qcom,msm8996-gic-v3", "arm,gic-v3";
 			#interrupt-cells = <3>;

arch/arm64/boot/dts/qcom/pm8994.dtsi

@@ -85,5 +85,9 @@
 		reg = <0x1 SPMI_USID>;
 		#address-cells = <1>;
 		#size-cells = <0>;
+
+		pm8994_spmi_regulators: regulators {
+			compatible = "qcom,pm8994-regulators";
+		};
 	};
 };