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SubjectRe: [PATCH v7 08/11] arm64: dts: mediatek: add ethernet support for mt8365-evk
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Il 11/05/23 18:29, Alexandre Mergnat ha scritto:
> - Enable "vibr" and "vsim2" regulators to power the ethernet chip.
>
> Tested-by: Kevin Hilman <khilman@baylibre.com>
> Signed-off-by: Alexandre Mergnat <amergnat@baylibre.com>
> ---
> arch/arm64/boot/dts/mediatek/mt8365-evk.dts | 57 +++++++++++++++++++++++++++++
> 1 file changed, 57 insertions(+)
>
> diff --git a/arch/arm64/boot/dts/mediatek/mt8365-evk.dts b/arch/arm64/boot/dts/mediatek/mt8365-evk.dts
> index 3a472f620ac0..cf81dace466a 100644
> --- a/arch/arm64/boot/dts/mediatek/mt8365-evk.dts
> +++ b/arch/arm64/boot/dts/mediatek/mt8365-evk.dts
> @@ -88,6 +88,28 @@ optee_reserved: optee@43200000 {
> };
> };
>
> +&ethernet {
> + pinctrl-0 = <&ethernet_pins>;
> + pinctrl-names = "default";
> + phy-handle = <&eth_phy>;
> + phy-mode = "rmii";
> + /*
> + * Ethernet and HDMI (DSI0) are sharing pins.
> + * Only one can be enabled at a time and require the physical switch
> + * SW2101 to be set on LAN position
> + */
> + status = "disabled";
> +
> + mdio {
> + #address-cells = <1>;
> + #size-cells = <0>;
> +
> + eth_phy: ethernet-phy@0 {
> + reg = <0>;
> + };
> + };
> +};
> +
> &i2c0 {
> clock-frequency = <100000>;
> pinctrl-0 = <&i2c0_pins>;
> @@ -137,12 +159,47 @@ &mt6357_pmic {
> #interrupt-cells = <2>;
> };
>
> +/* Needed by analog switch (multiplexer), HDMI and ethernet */

What part of the ethernet HW needs this regulator?

> +&mt6357_vibr_reg {
> + regulator-always-on;
> +};
> +
> /* Needed by MSDC IP */
> &mt6357_vmc_reg {
> regulator-always-on;
> };
>
> +/* Needed by ethernet */

Same question for this one. If a device needs us to turn on a regulator in
order for it to be powered (read: if the supply is not fixed-on), setting
that supply as always-on is not beneficial for anyone, as eventually in a
power-off sleep/idle/whatever-pm state, this device (whole chip or IP) *will*
leak some amount of power.

If hardware engineers decided to connect a device to a supply that *can be*
shut down entirely there must be a reason, right? :-)

Regards,
Angelo

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