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Date:   Wed, 11 Jul 2018 22:18:44 +0800
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Subject: Re: [linux-sunxi] [PATCH 2/2] ARM: sun8i: h3: add SY8113B regulator on Banana Pi M2 Zero board
To:     wens@csie.org, Chen-Yu Tsai <wens@csie.org>
CC:     Maxime Ripard <maxime.ripard@bootlin.com>,
        devicetree <devicetree@vger.kernel.org>,
        linux-arm-kernel <linux-arm-kernel@lists.infradead.org>,
        linux-kernel <linux-kernel@vger.kernel.org>,
        linux-sunxi <linux-sunxi@googlegroups.com>
From:   Icenowy Zheng <icenowy@aosc.io>
Message-ID: <9C53E8F0-C5F9-4730-AD72-1E6FA8793E4A@aosc.io>
Sender: linux-kernel-owner@vger.kernel.org
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于 2018年7月11日 GMT+08:00 下午10:15:41, Chen-Yu Tsai <wens@csie.org> 写到:
>Hi,
>
>On Wed, Jul 11, 2018 at 9:44 PM, Icenowy Zheng <icenowy@aosc.io> wrote:
>> Banana Pi M2 Zero board has a SY8113B regulator, which is controlled
>via
>> GPIO and capable of outputing 1.1V when the PL1 GPIO is set to output
>0
>> or 1.1V when the PL6 GPIO is set to input or output 1, and the output
>is
>> the power supply of the ARM cores in H3 SoC.
>>
>> Add the device tree node of this regulator and set the cpu's
>cpu-supply
>> property to it.
>>
>> Signed-off-by: Icenowy Zheng <icenowy@aosc.io>
>> ---
>>  .../dts/sun8i-h2-plus-bananapi-m2-zero.dts    | 21
>+++++++++++++++++++
>>  1 file changed, 21 insertions(+)
>>
>> diff --git a/arch/arm/boot/dts/sun8i-h2-plus-bananapi-m2-zero.dts
>b/arch/arm/boot/dts/sun8i-h2-plus-bananapi-m2-zero.dts
>> index eb61dcf32797..abc8dc750f4b 100644
>> --- a/arch/arm/boot/dts/sun8i-h2-plus-bananapi-m2-zero.dts
>> +++ b/arch/arm/boot/dts/sun8i-h2-plus-bananapi-m2-zero.dts
>> @@ -59,6 +59,23 @@
>>                 };
>>         };
>>
>> +       reg_vdd_cpux: vdd-cpux-regulator {
>> +               compatible = "regulator-gpio";
>> +               regulator-name = "vdd-cpux";
>> +               regulator-type = "voltage";
>> +               regulator-boot-on;
>> +               regulator-always-on;
>> +               regulator-min-microvolt = <1100000>;
>> +               regulator-max-microvolt = <1300000>;
>> +               regulator-ramp-delay = <50>; /* 4ms */
>> +
>> +               gpios = <&r_pio 0 1 GPIO_ACTIVE_HIGH>; /* PL1 */
>> +               enable-active-high;
>> +               gpios-states = <0x1>;
>> +               states = <1100000 0x0
>
>So looking at the schematics with the resistor values, this calculates
>to roughly 1.108475 (0.6 * (1 + 10 / 11.8)) ...
>
>> +                         1300000 0x1>;
>
>and this to 1.308475.

But I think it cannot reach such accuracy, because of the
error of component values and the error of the power voltage.

In addition, set it to a too accurate value may break the
common opp table.

>
>ChenYu
>
>> +       };
>> +
>>         wifi_pwrseq: wifi_pwrseq {
>>                 compatible = "mmc-pwrseq-simple";
>>                 pinctrl-names = "default";
>> @@ -66,6 +83,10 @@
>>         };
>>  };
>>
>> +&cpu0 {
>> +       cpu-supply = <&reg_vdd_cpux>;
>> +};
>> +
>>  &de {
>>         status = "okay";
>>  };
>> --
>> 2.17.1
>>
>> --
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