linux-kernel - Re: [PATCH v2 06/11] arm64: dts: meson-g12a-x96-max: add regulators

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Date:   Tue, 19 Mar 2019 09:29:03 +0100
From:   Neil Armstrong <narmstrong@...libre.com>
To:     Martin Blumenstingl <martin.blumenstingl@...glemail.com>
Cc:     khilman@...libre.com, linux-amlogic@...ts.infradead.org,
        Guillaume La Roque <glaroque@...libre.com>,
        linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH v2 06/11] arm64: dts: meson-g12a-x96-max: add regulators

On 18/03/2019 21:13, Martin Blumenstingl wrote:
> Hi Neil,
> 
> On Mon, Mar 18, 2019 at 11:06 AM Neil Armstrong <narmstrong@...libre.com> wrote:
>>
>> From: Guillaume La Roque <glaroque@...libre.com>
>>
>> Add system regulators for the X96 Max Set-Top-Box.
>>
>> Still missing
>> * VDD_EE (0.8V - PWM controlled)
>> * VDD_CPU (PWM controlled)
>>
>> Signed-off-by: Guillaume La Roque <glaroque@...libre.com>
>> Signed-off-by: Neil Armstrong <narmstrong@...libre.com>
>> ---
>>  .../boot/dts/amlogic/meson-g12a-x96-max.dts   | 67 +++++++++++++++++++
>>  1 file changed, 67 insertions(+)
>>
>> diff --git a/arch/arm64/boot/dts/amlogic/meson-g12a-x96-max.dts b/arch/arm64/boot/dts/amlogic/meson-g12a-x96-max.dts
>> index 0edbd00b358f..5c37930b09e2 100644
>> --- a/arch/arm64/boot/dts/amlogic/meson-g12a-x96-max.dts
>> +++ b/arch/arm64/boot/dts/amlogic/meson-g12a-x96-max.dts
> [...]
>> +       vcc_5v: regulator-vcc_5v {
>> +               compatible = "regulator-fixed";
>> +               regulator-name = "VCC_5V";
>> +               regulator-min-microvolt = <5000000>;
>> +               regulator-max-microvolt = <5000000>;
>> +               vin-supply = <&dc_in>;
>> +
>> +               gpio = <&gpio GPIOH_8 GPIO_OPEN_DRAIN>;
>> +               enable-active-high;
> is there any way to test whether this GPIO is the right one?
> I couldn't find a reference to a GPIOH_8 regulator in
> buildroot_openlinux_kernel_4.9_fbdev_20180706

The x96 is based on the U212 reference design, and the GPIOH_8 controls the 5V_EN signal,
but you are right, it's the wrong polarity here, it should be enable-active-low instead.
(FYI The SEI510 does not use this at all, 5V is always enabled)

The schematics describes :
VCC5V_EN (GPIOH_8-Hiz OD): 5V_EN
L: Enable
Hiz: Disable

FYI, the GPIOH_8 is Open-Drain only, this means this pin cannot pull to TTL 1, only to TTL 0
or set as input. We need to add a way to describe this in the pinctrl driver somehow....

I will send a fix on v3

I didn't notice because I power the board using a Type-A to Type-A connector,
and the 5V from the USB port bypasses this regulator...

Neil

> 
> 
> Regards
> Martin
>