Re: [PATCH 1/3] arm64: dts: mediatek: asurada: Add display regulators

Hi Chen-Yu,

thank you for the insights on the power supply hierarchy. Just a couple further
questions below.

On Wed, Sep 21, 2022 at 10:20:43PM +0800, Chen-Yu Tsai wrote:

Hi,

On Fri, Sep 9, 2022 at 1:12 AM Nícolas F. R. A. Prado
[off-list ref] wrote:

quoted

Add the regulators present on the Asurada platform that are used to
power the internal and external displays.

Signed-off-by: Nícolas F. R. A. Prado <redacted>

---

 .../boot/dts/mediatek/mt8192-asurada.dtsi     | 114 ++++++++++++++++++
 1 file changed, 114 insertions(+)

diff --git a/arch/arm64/boot/dts/mediatek/mt8192-asurada.dtsi b/arch/arm64/boot/dts/mediatek/mt8192-asurada.dtsi
index 4b314435f8fd..1d99e470ea1a 100644
--- a/arch/arm64/boot/dts/mediatek/mt8192-asurada.dtsi
+++ b/arch/arm64/boot/dts/mediatek/mt8192-asurada.dtsi

@@ -23,6 +23,42 @@ memory@40000000 {
                reg = <0 0x40000000 0 0x80000000>;
        };

+       pp1000_dpbrdg: regulator-1v0-dpbrdg {
+               compatible = "regulator-fixed";
+               regulator-name = "pp1000_dpbrdg";
+               pinctrl-names = "default";
+               pinctrl-0 = <&pp1000_dpbrdg_en_pins>;
+               regulator-min-microvolt = <1000000>;
+               regulator-max-microvolt = <1000000>;

This is fed by a rail called PP1350_VS2, which is from the MT6359 PMIC.
And this regulator is a proper LDO.

So, we should have an additional regulator node here called pp1350_vs2 which
will feed into pp1000_dpbrdg and that is itself fed in from mt6359_vs2_buck_reg
(from mt6359.dtsi). Is that right?

Also, is PP1350_VS2 just a simple switch or an LDO?

[..]

quoted

+       pp1800_dpbrdg: regulator-1v8-dpbrdg {
+               compatible = "regulator-fixed";
+               regulator-name = "pp1800_dpbrdg";
+               pinctrl-names = "default";
+               pinctrl-0 = <&pp1800_dpbrdg_en_pins>;
+               regulator-min-microvolt = <1800000>;
+               regulator-max-microvolt = <1800000>;

This regulator is only a power switch. Please drop the min/max properties.
This is fed by a rail called PP1800_VIO18_U, which is from an LDO on the
MT6359 PMIC.

Similarly, we should have a pp1800_vio18_u node that is fed in by
mt6359_vio18_ldo_reg, right? And is it a switch or an LDO?

Thanks,
Nícolas

quoted

+               enable-active-high;
+               regulator-boot-on;
+               gpio = <&pio 126 GPIO_ACTIVE_HIGH>;
+       };
+

[..]

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