linux-kernel - Re: [PATCH] arm64: dts: amlogic: odroid-n2: set usb-pwr-en regulator always on

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Message-ID: <1jpnedzmr2.fsf@starbuckisacylon.baylibre.com>
Date:   Mon, 17 Feb 2020 08:38:57 +0100
From:   Jerome Brunet <jbrunet@...libre.com>
To:     Anand Moon <linux.amoon@...il.com>,
        Rob Herring <robh+dt@...nel.org>,
        Kevin Hilman <khilman@...libre.com>,
        Martin Blumenstingl <martin.blumenstingl@...glemail.com>,
        Neil Armstrong <narmstrong@...libre.com>
Cc:     devicetree@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-amlogic@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] arm64: dts: amlogic: odroid-n2: set usb-pwr-en regulator always on


On Sun 16 Feb 2020 at 21:21, Anand Moon <linux.amoon@...il.com> wrote:

> usb-pwr-en regulator is getting disable after booting, setting
> regulator-alway-on help enable the regulator after booting.

This explains what your patch does, not why it needs to be done.
Why does this regulator need be on at all time ? What device needs it
and cannot claim it properly ?

>
> [   31.766097] USB_PWR_EN: disabling
>
> Fixes: c35f6dc5c377 (arm64: dts: meson: Add minimal support for Odroid-N2)
> Cc: Martin Blumenstingl <martin.blumenstingl@...glemail.com>
> Cc: Jerome Brunet <jbrunet@...libre.com>
> Cc: Neil Armstrong <narmstrong@...libre.com>
> Signed-off-by: Anand Moon <linux.amoon@...il.com>
> ---
> Patch generated on top of my earier patch.
> [0] https://patchwork.kernel.org/patch/11384531/
> [1] https://patchwork.kernel.org/patch/11384533/
>
> Before
> [root@...rm ~]# cat /sys/kernel/debug/regulator/regulator_summary | grep USB
>        USB_PWR_EN                 0    1      0 unknown  5000mV     0mA  5000mV  5000mV
> After
> [root@...rm ~]# cat /sys/kernel/debug/regulator/regulator_summary | grep USB
>        USB_PWR_EN                 1    1      0 unknown  5000mV     0mA  5000mV  5000mV
> ---
>  arch/arm64/boot/dts/amlogic/meson-g12b-odroid-n2.dts | 1 +
>  1 file changed, 1 insertion(+)
>
> diff --git a/arch/arm64/boot/dts/amlogic/meson-g12b-odroid-n2.dts b/arch/arm64/boot/dts/amlogic/meson-g12b-odroid-n2.dts
> index 23eddff85fe5..938a9e15adfc 100644
> --- a/arch/arm64/boot/dts/amlogic/meson-g12b-odroid-n2.dts
> +++ b/arch/arm64/boot/dts/amlogic/meson-g12b-odroid-n2.dts
> @@ -177,6 +177,7 @@ usb_pwr_en: regulator-usb_pwr_en {
>  		regulator-min-microvolt = <5000000>;
>  		regulator-max-microvolt = <5000000>;
>  		vin-supply = <&vcc_5v>;
> +		regulator-always-on;
>  
>  		/* Connected to the microUSB port power enable */
>  		gpio = <&gpio GPIOH_6 GPIO_ACTIVE_HIGH>;