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From:   "Milton Miller II" <miltonm@us.ibm.com>
To:     Steven Lee <steven_lee@aspeedtech.com>
Cc:     Rob Herring <robh@kernel.org>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@vger.kernel.org>, Ulf Hansson <ulf.hansson@linaro.org>,
        Ryan Chen <ryan_chen@aspeedtech.com>,
        "moderated list:ASPEED SD/MMC DRIVER" <linux-aspeed@lists.ozlabs.org>,
        Andrew Jeffery <andrew@aj.id.au>,
        "open list:ASPEED SD/MMC DRIVER" <linux-mmc@vger.kernel.org>,
        "moderated list:ASPEED SD/MMC DRIVER" <openbmc@lists.ozlabs.org>,
        Ryan Chen <ryanchen.aspeed@gmail.com>,
        Adrian Hunter <adrian.hunter@intel.com>,
        open list <linux-kernel@vger.kernel.org>,
        Chin-Ting Kuo <chin-ting_kuo@aspeedtech.com>,
        "moderated list:ARM/ASPEED MACHINE SUPPORT" 
        <linux-arm-kernel@lists.infradead.org>
Date:   Tue, 13 Apr 2021 02:43:14 +0000
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References: <20210413013010.GA353@aspeedtech.com>,<20210408015218.20560-1-steven_lee@aspeedtech.com>
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Subject: RE: [PATCH v1 1/2] dt-bindings: mmc: sdhci-of-aspeed: Add power-gpio and
 power-switch-gpio
Precedence: bulk


-----"openbmc" <openbmc-bounces+miltonm=3Dus.ibm.com@lists.ozlabs.org> wrot=
e: -----

>To: Rob Herring <robh@kernel.org>
>From: Steven Lee=20
>Sent by: "openbmc"=20
>Date: 04/12/2021 08:31PM
>Cc: "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS"
><devicetree@vger.kernel.org>, Ulf Hansson <ulf.hansson@linaro.org>,
>Ryan Chen <ryan_chen@aspeedtech.com>, "moderated list:ASPEED SD/MMC
>DRIVER" <linux-aspeed@lists.ozlabs.org>, Andrew Jeffery
><andrew@aj.id.au>, "open list:ASPEED SD/MMC DRIVER"
><linux-mmc@vger.kernel.org>, "moderated list:ASPEED SD/MMC DRIVER"
><openbmc@lists.ozlabs.org>, Ryan Chen <ryanchen.aspeed@gmail.com>,
>Adrian Hunter <adrian.hunter@intel.com>, open list
><linux-kernel@vger.kernel.org>, Chin-Ting Kuo
><chin-ting_kuo@aspeedtech.com>, "moderated list:ARM/ASPEED MACHINE
>SUPPORT" <linux-arm-kernel@lists.infradead.org>
>Subject: [EXTERNAL] Re: [PATCH v1 1/2] dt-bindings: mmc:
>sdhci-of-aspeed: Add power-gpio and power-switch-gpio
>
>The 04/10/2021 02:41, Rob Herring wrote:
>> On Thu, Apr 08, 2021 at 09:52:17AM +0800, Steven Lee wrote:
>> > AST2600-A2 EVB provides the reference design for enabling SD bus
>power
>> > and toggling SD bus signal voltage by GPIO pins.
>> > Add the definition and example for power-gpio and
>power-switch-gpio
>> > properties.
>> >=20
>> > In the reference design, GPIOV0 of AST2600-A2 EVB is connected to
>power
>> > load switch that providing 3.3v to SD1 bus vdd. GPIOV1 is
>connected to
>> > a 1.8v and a 3.3v power load switch that providing signal voltage
>to
>> > SD1 bus.
>> > If GPIOV0 is active high, SD1 bus is enabled. Otherwise, SD1 bus
>is
>> > disabled.
>> > If GPIOV1 is active high, 3.3v power load switch is enabled, SD1
>signal
>> > voltage is 3.3v. Otherwise, 1.8v power load switch will be
>enabled, SD1
>> > signal voltage becomes 1.8v.
>> >=20
>> > AST2600-A2 EVB also support toggling signal voltage for SD2 bus.
>> > The design is the same as SD1 bus. It uses GPIOV2 as power-gpio
>and GPIOV3
>> > as power-switch-gpio.
>> >=20
>> > Signed-off-by: Steven Lee <steven_lee@aspeedtech.com>
>> > ---
>> >  .../devicetree/bindings/mmc/aspeed,sdhci.yaml | 25
>+++++++++++++++++++
>> >  1 file changed, 25 insertions(+)
>> >=20
>> > diff --git
>a/Documentation/devicetree/bindings/mmc/aspeed,sdhci.yaml
>b/Documentation/devicetree/bindings/mmc/aspeed,sdhci.yaml
>> > index 987b287f3bff..515a74614f3c 100644
>> > --- a/Documentation/devicetree/bindings/mmc/aspeed,sdhci.yaml
>> > +++ b/Documentation/devicetree/bindings/mmc/aspeed,sdhci.yaml
>> > @@ -37,6 +37,14 @@ properties:
>> >    clocks:
>> >      maxItems: 1
>> >      description: The SD/SDIO controller clock gate
>> > +  power-gpio:
>>=20
>> '-gpios' is the preferred form even if just 1.
>>=20
>
>Thanks for reviewing, I will change the name.

is this a clock gate or a power on gpio?


>
>> > +    description:
>> > +      The GPIO for enabling/disabling SD bus power.
>> > +    maxItems: 1
>>=20
>> blank line
>>=20
>
>I will remove the blank line.
>
>> > +  power-switch-gpio:
>> > +    description:
>> > +      The GPIO for toggling the signal voltage between 3.3v and
>1.8v.

Which way does it toggle for which voltage?

Oh, you said in the change log but not in the binding.

But please, use gpio controled regulators as Ulf suggested and is
already used by other mmc controllers upstream.

https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/
Documentation/devicetree/bindings/regulator/gpio-regulator.yaml

Ulf> Please do not model these as GPIO pins like this. Instead, it's better
Ulf> to model them as gpio regulators, since the mmc core manages them as
Ulf> regulators.
Ulf>=20
Ulf> We have a vmmc regulator (corresponding to vdd) and a vqmmc regulator
Ulf> (corresponding the signal-voltage level). These are also described in
Ulf> the common mmc DT bindings, see
Ulf> Documentation/devicetree/bindings/mmc/mmc-controller.yaml
Ulf> .

milton

>> > +    maxItems: 1
>> >=20=20
>> >  patternProperties:
>> >    "^sdhci@[0-9a-f]+$":
>> > @@ -61,6 +69,14 @@ patternProperties:
>> >        sdhci,auto-cmd12:
>> >          type: boolean
>> >          description: Specifies that controller should use auto
>CMD12
>> > +      power-gpio:
>> > +        description:
>> > +          The GPIO for enabling/disabling SD bus power.
>> > +        maxItems: 1
>> > +      power-switch-gpio:
>> > +        description:
>> > +          The GPIO for toggling the signal voltage between 3.3v
>and 1.8v.
>> > +        maxItems: 1
>> >      required:
>> >        - compatible
>> >        - reg
>> > @@ -80,6 +96,7 @@ required:
>> >  examples:
>> >    - |
>> >      #include <dt-bindings/clock/aspeed-clock.h>
>> > +    #include <dt-bindings/gpio/aspeed-gpio.h>
>> >      sdc@1e740000 {
>> >              compatible =3D "aspeed,ast2500-sd-controller";
>> >              reg =3D <0x1e740000 0x100>;
>> > @@ -94,6 +111,10 @@ examples:
>> >                      interrupts =3D <26>;
>> >                      sdhci,auto-cmd12;
>> >                      clocks =3D <&syscon ASPEED_CLK_SDIO>;
>> > +                    power-gpio =3D <&gpio0 ASPEED_GPIO(V, 0)
>> > +                                     GPIO_ACTIVE_HIGH>;
>> > +                    power-switch-gpio =3D <&gpio0 ASPEED_GPIO(V,
>1)
>> > +                                     GPIO_ACTIVE_HIGH>;
>> >              };
>> >=20=20
>> >              sdhci1: sdhci@200 {
>> > @@ -102,5 +123,9 @@ examples:
>> >                      interrupts =3D <26>;
>> >                      sdhci,auto-cmd12;
>> >                      clocks =3D <&syscon ASPEED_CLK_SDIO>;
>> > +                    power-gpio =3D <&gpio0 ASPEED_GPIO(V, 2)
>> > +                                     GPIO_ACTIVE_HIGH>;
>> > +                    power-switch-gpio =3D <&gpio0 ASPEED_GPIO(V,
>3)
>> > +                                     GPIO_ACTIVE_HIGH>;
>> >              };
>> >      };
>> > --=20
>> > 2.17.1
>> >=20
>
>