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

[Neil Armstrong <narmstrong@baylibre.com>]

On 19/03/2019 21:13, Martin Blumenstingl wrote:
> Hi Neil,
> 
> On Tue, Mar 19, 2019 at 9:29 AM Neil Armstrong <narmstrong@baylibre.com> wrote:
>>
>> On 18/03/2019 21:13, Martin Blumenstingl wrote:
>>> Hi Neil,
>>>
>>> On Mon, Mar 18, 2019 at 11:06 AM Neil Armstrong <narmstrong@baylibre.com> wrote:
>>>>
>>>> From: Guillaume La Roque <glaroque@baylibre.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@baylibre.com>
>>>> Signed-off-by: Neil Armstrong <narmstrong@baylibre.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
> thank you for this explanation!
> 
>> 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....
> as far as I understand the pinctrl driver changes would result in an
> error when the GPIO is used with "active high" (making incompatible
> drivers or .dts easier to see). is this correct?

I don't have a clear view of that, since it's really GPIO related.
I don't know if we can really disable non-opendrain support for a
specific gpio.

We will need to investigate ! Anyway, using GPIO_OPEN_DRAIN in DT
is the correct way to handle these GPIO lines.

Neil

> 
>> 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...
> this is good to know.
> I'm also powering some of my boards using a Type-A to Type-A
> connector. I'll need to remember this and this whether boards are
> still booting with the DC plug
> 
> 
> Regards
> Martin
>