linux-kernel - Re: [PATCH v1 1/2] dt-bindings: mmc: sdhci-of-aspeed: Add power-gpio and power-switch-gpio

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Message-ID: <20210413033155.GA3522@aspeedtech.com>
Date:   Tue, 13 Apr 2021 11:31:56 +0800
From:   Steven Lee <steven_lee@...eedtech.com>
To:     Ulf Hansson <ulf.hansson@...aro.org>
CC:     Andrew Jeffery <andrew@...id.au>, Rob Herring <robh+dt@...nel.org>,
        "Joel Stanley" <joel@....id.au>,
        Adrian Hunter <adrian.hunter@...el.com>,
        Ryan Chen <ryanchen.aspeed@...il.com>,
        "moderated list:ASPEED SD/MMC DRIVER" <linux-aspeed@...ts.ozlabs.org>,
        "moderated list:ASPEED SD/MMC DRIVER" <openbmc@...ts.ozlabs.org>,
        "open list:ASPEED SD/MMC DRIVER" <linux-mmc@...r.kernel.org>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@...r.kernel.org>,
        "moderated list:ARM/ASPEED MACHINE SUPPORT" 
        <linux-arm-kernel@...ts.infradead.org>,
        open list <linux-kernel@...r.kernel.org>,
        Ryan Chen <ryan_chen@...eedtech.com>,
        Chin-Ting Kuo <chin-ting_kuo@...eedtech.com>
Subject: Re: [PATCH v1 1/2] dt-bindings: mmc: sdhci-of-aspeed: Add power-gpio
 and power-switch-gpio

The 04/12/2021 15:38, Ulf Hansson wrote:
> On Thu, 8 Apr 2021 at 03:52, Steven Lee <steven_lee@...eedtech.com> 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.
> >
> > 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.
> >
> > 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.
> 
> Thanks for sharing the details, it certainly helps while reviewing.
> 
> >
> > Signed-off-by: Steven Lee <steven_lee@...eedtech.com>
> > ---
> >  .../devicetree/bindings/mmc/aspeed,sdhci.yaml | 25 +++++++++++++++++++
> >  1 file changed, 25 insertions(+)
> >
> > 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:
> > +    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
> 
> 
> >
> >  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:
> 
> Please do not model these as GPIO pins like this. Instead, it's better
> to model them as gpio regulators, since the mmc core manages them as
> regulators.
> 
> We have a vmmc regulator (corresponding to vdd) and a vqmmc regulator
> (corresponding the signal-voltage level). These are also described in
> the common mmc DT bindings, see
> Documentation/devicetree/bindings/mmc/mmc-controller.yaml.
> 

Thanks for the information. I will modify it.

> >        - compatible
> >        - reg
> > @@ -80,6 +96,7 @@ required:
> >  examples:
> >    - |
> >      #include <dt-bindings/clock/aspeed-clock.h>
> > +    #include <dt-bindings/gpio/aspeed-gpio.h>
> >      sdc@...40000 {
> >              compatible = "aspeed,ast2500-sd-controller";
> >              reg = <0x1e740000 0x100>;
> > @@ -94,6 +111,10 @@ examples:
> >                      interrupts = <26>;
> >                      sdhci,auto-cmd12;
> >                      clocks = <&syscon ASPEED_CLK_SDIO>;
> > +                    power-gpio = <&gpio0 ASPEED_GPIO(V, 0)
> > +                                     GPIO_ACTIVE_HIGH>;
> > +                    power-switch-gpio = <&gpio0 ASPEED_GPIO(V, 1)
> > +                                     GPIO_ACTIVE_HIGH>;
> >              };
> >
> >              sdhci1: sdhci@200 {
> > @@ -102,5 +123,9 @@ examples:
> >                      interrupts = <26>;
> >                      sdhci,auto-cmd12;
> >                      clocks = <&syscon ASPEED_CLK_SDIO>;
> > +                    power-gpio = <&gpio0 ASPEED_GPIO(V, 2)
> > +                                     GPIO_ACTIVE_HIGH>;
> > +                    power-switch-gpio = <&gpio0 ASPEED_GPIO(V, 3)
> > +                                     GPIO_ACTIVE_HIGH>;
> >              };
> >      };
> 
> Kind regards
> Uffe