[PATCH v2] ARM: dts: sun8i: Open FETA40i-C regulator aldo1

[Fuyao Kashizuku <fuyao@xxxxxxxxxx>]

The USB PHY in the Allwinner R40 SoC seems to rely on voltage on the
VCC-TVIN/OUT supply pins for proper operation, on top of its own supply
voltage on VCC-USB. Without a 3.3V voltage supplied to VCC-TV*, USB
operation becomes unstable and can result in disconnects.

The Forlinx FETA40i-C SoM connects both the VCC-TVOUT and VCC-TVIN pins
to the ALDO1 rail of the PMIC, so we need to enable that rail for USB
operation. Since there is no supply property in the DT bindings for
the USB core, we need to always enable the regulator.

This fixes unstable USB operation on boards using the Forlinx FETA40i-C
module.

Signed-off-by: Fuyao Kashizuku <fuyao@xxxxxxxxxx>
---
Changes in v2:
 - Subject include board name.
 - regulator name changed to vcc-3v3-tv-usb.
 - explain why we need to enable the regulator.
 - use full name of the commiter
 - Link to v1: https://lore.kernel.org/lkml/ZYKjYypuAx7gNuam@xxxxxxxxxx/

 arch/arm/boot/dts/allwinner/sun8i-r40-feta40i.dtsi | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/arch/arm/boot/dts/allwinner/sun8i-r40-feta40i.dtsi b/arch/arm/boot/dts/allwinner/sun8i-r40-feta40i.dtsi
index 9f39b5a2bb35..c12361d0317f 100644
--- a/arch/arm/boot/dts/allwinner/sun8i-r40-feta40i.dtsi
+++ b/arch/arm/boot/dts/allwinner/sun8i-r40-feta40i.dtsi
@@ -42,6 +42,13 @@ &pio {
 	vcc-pg-supply = <&reg_dldo1>;
 };
 
+&reg_aldo1 {
+	regulator-always-on;
+	regulator-min-microvolt = <3300000>;
+	regulator-max-microvolt = <3300000>;
+	regulator-name = "vcc-3v3-tv-usb";
+};
+
 &reg_aldo2 {
 	regulator-always-on;
 	regulator-min-microvolt = <1800000>;
-- 
2.39.2