linux-kernel - [PATCH v2] arm64: dts: allwinner: h6: Use dummy regulator for Tanix TX6

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Date:   Tue, 28 Apr 2020 16:26:29 +0200
From:   Clément Péron <peron.clem@...il.com>
To:     Maxime Ripard <mripard@...nel.org>, Chen-Yu Tsai <wens@...e.org>,
        Rob Herring <robh+dt@...nel.org>
Cc:     linux-arm-kernel@...ts.infradead.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        linux-sunxi <linux-sunxi@...glegroups.com>,
        Clément Péron <peron.clem@...il.com>,
        Piotr Oniszczuk <warpme@...pl>
Subject: [PATCH v2] arm64: dts: allwinner: h6: Use dummy regulator for Tanix TX6

Tanix TX6 has a fixed regulator. As DVFS is instructed to change
voltage to meet OPP table, the DVFS is not working as expected.

Avoid to introduce a new dedicated OPP Table where voltage are
equals to the fixed regulator as it will only duplicate all the OPPs.
Instead remove the fixed regulator so the DVFS framework will create
dummy regulator and will have the same behavior.

Add some comments to explain this in the device-tree.

Reported-by: Piotr Oniszczuk <warpme@...pl>
Fixes: add1e27fb703 ("arm64: dts: allwinner: h6: Enable CPU opp tables for Tanix TX6")
Signed-off-by: Clément Péron <peron.clem@...il.com>
---
 .../boot/dts/allwinner/sun50i-h6-tanix-tx6.dts | 18 ++++++++++++++++--
 1 file changed, 16 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/boot/dts/allwinner/sun50i-h6-tanix-tx6.dts b/arch/arm64/boot/dts/allwinner/sun50i-h6-tanix-tx6.dts
index be81330db14f..3e96fcb317ea 100644
--- a/arch/arm64/boot/dts/allwinner/sun50i-h6-tanix-tx6.dts
+++ b/arch/arm64/boot/dts/allwinner/sun50i-h6-tanix-tx6.dts
@@ -48,7 +48,15 @@
 };
 
 &cpu0 {
-	cpu-supply = <&reg_vdd_cpu_gpu>;
+	/*
+	 * Don't specify the CPU regulator, as it's a fixed
+	 * regulator DVFS will not work as it is intructed
+	 * to reach a voltage which can't be reached.
+	 * Not specifying a regulator will create a dummy
+	 * regulator allowing all OPPs.
+	 *
+	 * cpu-supply = <&reg_vdd_cpu_gpu>;
+	 */
 };
 
 &de {
@@ -68,7 +76,13 @@
 };
 
 &gpu {
-	mali-supply = <&reg_vdd_cpu_gpu>;
+	/*
+	 * Don't specify the GPU regulator, see comment
+	 * above for the CPU supply.
+	 *
+	 * mali-supply = <&reg_vdd_cpu_gpu>;
+	 */
+
 	status = "okay";
 };
 
-- 
2.20.1