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Date:   Fri, 27 Apr 2018 15:12:42 +0800
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Subject: Re: [linux-sunxi] [PATCH 3/3] arm64: allwinner: h6: enable MMC0/2 on Pine H64
To:     Andre Przywara <andre.przywara@arm.com>,
        Ulf Hansson <ulf.hansson@linaro.org>,
        Rob Herring <robh+dt@kernel.org>,
        Maxime Ripard <maxime.ripard@bootlin.com>,
        Chen-Yu Tsai <wens@csie.org>
CC:     linux-mmc@vger.kernel.org, devicetree@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org,
        linux-sunxi@googlegroups.com
From:   Icenowy Zheng <icenowy@aosc.io>
Message-ID: <83EDF187-5EB2-4FEB-99BC-9D5B728D3A45@aosc.io>
Sender: linux-kernel-owner@vger.kernel.org
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于 2018年4月27日 GMT+08:00 上午12:46:26, Andre Przywara <andre.przywara@arm.com> 写到:
>Hi,
>
>On 26/04/18 15:07, Icenowy Zheng wrote:
>> The Pine H64 board have a MicroSD slot connected to MMC0 controller
>of
>> the H6 SoC and a eMMC slot connected to MMC2.
>> 
>> Enable them in the device tree.
>> 
>> Signed-off-by: Icenowy Zheng <icenowy@aosc.io>
>> ---
>>  .../boot/dts/allwinner/sun50i-h6-pine-h64.dts      | 32
>++++++++++++++++++++++
>>  1 file changed, 32 insertions(+)
>> 
>> diff --git a/arch/arm64/boot/dts/allwinner/sun50i-h6-pine-h64.dts
>b/arch/arm64/boot/dts/allwinner/sun50i-h6-pine-h64.dts
>> index d36de5eb81f3..78b1cd54687c 100644
>> --- a/arch/arm64/boot/dts/allwinner/sun50i-h6-pine-h64.dts
>> +++ b/arch/arm64/boot/dts/allwinner/sun50i-h6-pine-h64.dts
>> @@ -20,6 +20,38 @@
>>  	chosen {
>>  		stdout-path = "serial0:115200n8";
>>  	};
>> +
>> +	reg_vcc3v3: vcc3v3 {
>> +		compatible = "regulator-fixed";
>> +		regulator-name = "vcc3v3";
>> +		regulator-min-microvolt = <3300000>;
>> +		regulator-max-microvolt = <3300000>;
>> +	};
>> +
>> +	reg_vcc1v8: vcc1v8 {
>> +		compatible = "regulator-fixed";
>> +		regulator-name = "vcc1v8";
>> +		regulator-min-microvolt = <1800000>;
>> +		regulator-max-microvolt = <1800000>;
>> +	};
>> +};
>> +
>> +&mmc0 {
>> +	pinctrl-names = "default";
>> +	pinctrl-0 = <&mmc0_pins>;
>> +	vmmc-supply = <&reg_vcc3v3>;
>
>So this is actually CLDO1 on the AXP, correct?

I remember it's coupled between two LDOs, to provide enough power.

>
>
>> +	cd-gpios = <&pio 5 6 GPIO_ACTIVE_LOW>;
>> +	status = "okay";
>> +};
>> +
>> +&mmc2 {
>> +	pinctrl-names = "default";
>> +	pinctrl-0 = <&mmc2_pins>;
>> +	vmmc-supply = <&reg_vcc3v3>;
>> +	vqmmc-supply = <&reg_vcc1v8>;
>
>And this is BLDO2?

Yes.

>
>I am just asking because I want to avoid running into the same problem
>as with the A64 before: that future DTs become incompatible with older
>kernels, because we change the power supply to point to the AXP
>regulators, which this kernel does not support yet.

The answer is just not to keep this compatibility, as it's not
supported option to update DT without updating kernel.

P.S. I think the DT will update twice on the kernel side, the
first time keep reg_vcc3v3 (as it's coupled) but use real
regulator for reg_vcc1v8, the second time use the real
coupled regulator for reg_vcc3v3.

>
>It looks like there are more users of those power rails, so we could
>keep those supplies connected to these fixed regulators here, even with
>AXP-805 support in the kernel.

It's not a good choice.

>
>Or we keep this back until we get proper AXP support in the kernel? I
>guess it's quite close to the existing PMICs, so it might be more a
>copy&paste exercise to support the AXP-805?

It's not a reason to keep it back.

>
>But apart from this this looks correct to me.
>
>Cheers,
>Andre.
>
>> +	non-removable;
>> +	cap-mmc-hw-reset;
>> +	status = "okay";
>>  };
>>  
>>  &uart0 {
>>