Re: [PATCH v1 1/2] dt-bindings: mmc: sdhci-of-aspeed: Add power-gpio and power-switch-gpio
From: Steven Lee
Date: Mon Apr 12 2021 - 23:38:39 EST
The 04/13/2021 10:43, Milton Miller II wrote:
>
>
> -----"openbmc" <openbmc-bounces+miltonm=us.ibm.com@xxxxxxxxxxxxxxxx> wrote: -----
>
> >To: Rob Herring <robh@xxxxxxxxxx>
> >From: Steven Lee
> >Sent by: "openbmc"
> >Date: 04/12/2021 08:31PM
> >Cc: "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS"
> ><devicetree@xxxxxxxxxxxxxxx>, Ulf Hansson <ulf.hansson@xxxxxxxxxx>,
> >Ryan Chen <ryan_chen@xxxxxxxxxxxxxx>, "moderated list:ASPEED SD/MMC
> >DRIVER" <linux-aspeed@xxxxxxxxxxxxxxxx>, Andrew Jeffery
> ><andrew@xxxxxxxx>, "open list:ASPEED SD/MMC DRIVER"
> ><linux-mmc@xxxxxxxxxxxxxxx>, "moderated list:ASPEED SD/MMC DRIVER"
> ><openbmc@xxxxxxxxxxxxxxxx>, Ryan Chen <ryanchen.aspeed@xxxxxxxxx>,
> >Adrian Hunter <adrian.hunter@xxxxxxxxx>, open list
> ><linux-kernel@xxxxxxxxxxxxxxx>, Chin-Ting Kuo
> ><chin-ting_kuo@xxxxxxxxxxxxxx>, "moderated list:ARM/ASPEED MACHINE
> >SUPPORT" <linux-arm-kernel@xxxxxxxxxxxxxxxxxxx>
> >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.
> >> >
> >> > 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.
> >> >
> >> > Signed-off-by: Steven Lee <steven_lee@xxxxxxxxxxxxxx>
> >> > ---
> >> > .../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:
> >>
> >> '-gpios' is the preferred form even if just 1.
> >>
> >
> >Thanks for reviewing, I will change the name.
>
> is this a clock gate or a power on gpio?
>
>
A power on gpio.
> >
> >> > + description:
> >> > + The GPIO for enabling/disabling SD bus power.
> >> > + maxItems: 1
> >>
> >> blank line
> >>
> >
> >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.
>
I will add description 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
>
Thanks for reviewing and the information, I will use gpio-regulator
instead of power-gpio and power-switch-gpio.
> 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>
> 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
> >> >
> >> > 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 = "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>;
> >> > };
> >> > };
> >> > --
> >> > 2.17.1
> >> >
> >
> >
>