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

2021-04-12 Thread Steven Lee
The 04/13/2021 10:43, Milton Miller II wrote:
> 
> 
> -"openbmc"  wrote: 
> -
> 
> >To: Rob Herring 
> >From: Steven Lee 
> >Sent by: "openbmc" 
> >Date: 04/12/2021 08:31PM
> >Cc: "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS"
> >, Ulf Hansson ,
> >Ryan Chen , "moderated list:ASPEED SD/MMC
> >DRIVER" , Andrew Jeffery
> >, "open list:ASPEED SD/MMC DRIVER"
> >, "moderated list:ASPEED SD/MMC DRIVER"
> >, Ryan Chen ,
> >Adrian Hunter , open list
> >, Chin-Ting Kuo
> >, "moderated list:ARM/ASPEED MACHINE
> >SUPPORT" 
> >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 
> >> > ---
> >> >  .../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

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

2021-04-12 Thread Steven Lee
The 04/12/2021 15:38, Ulf Hansson wrote:
> On Thu, 8 Apr 2021 at 03:52, 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.
> 
> Thanks for sharing the details, it certainly helps while reviewing.
> 
> >
> > Signed-off-by: Steven Lee 
> > ---
> >  .../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 
> > +#include 
> >  sdc@1e74 {
> >  compatible = "aspeed,ast2500-sd-controller";
> >  reg = <0x1e74 0x100>;
> > @@ -94,6 +111,10 @@ examples:
> >  interrupts = <26>;
> >  sdhci,auto-cmd12;
> >  clocks = < ASPEED_CLK_SDIO>;
> > +power-gpio = < ASPEED_GPIO(V, 0)
> > + GPIO_ACTIVE_HIGH>;
> > +power-switch-gpio = < ASPEED_GPIO(V, 1)
> > + GPIO_ACTIVE_HIGH>;
> >  };
> >
> >  sdhci1: sdhci@200 {
> > @@ -102,5 +123,9 @@ examples:
> >  interrupts = <26>;
> >  sdhci,auto-cmd12;
> >  clocks = < ASPEED_CLK_SDIO>;
> > +power-gpio = < ASPEED_GPIO(V, 2)
> > + GPIO_ACTIVE_HIGH>;
> > +power-switch-gpio = < ASPEED_GPIO(V, 3)
> > + GPIO_ACTIVE_HIGH>;
> >  };
> >  };
> 
> Kind regards
> Uffe


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

2021-04-12 Thread Milton Miller II



-"openbmc"  wrote: 
-

>To: Rob Herring 
>From: Steven Lee 
>Sent by: "openbmc" 
>Date: 04/12/2021 08:31PM
>Cc: "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS"
>, Ulf Hansson ,
>Ryan Chen , "moderated list:ASPEED SD/MMC
>DRIVER" , Andrew Jeffery
>, "open list:ASPEED SD/MMC DRIVER"
>, "moderated list:ASPEED SD/MMC DRIVER"
>, Ryan Chen ,
>Adrian Hunter , open list
>, Chin-Ting Kuo
>, "moderated list:ARM/ASPEED MACHINE
>SUPPORT" 
>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 
>> > ---
>> >  .../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?


>
>> > +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.

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> 
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:
>> >- |
>&

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

2021-04-12 Thread Steven Lee
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 
> > ---
> >  .../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.

> > +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.
> > +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 
> > +#include 
> >  sdc@1e74 {
> >  compatible = "aspeed,ast2500-sd-controller";
> >  reg = <0x1e74 0x100>;
> > @@ -94,6 +111,10 @@ examples:
> >  interrupts = <26>;
> >  sdhci,auto-cmd12;
> >  clocks = < ASPEED_CLK_SDIO>;
> > +power-gpio = < ASPEED_GPIO(V, 0)
> > + GPIO_ACTIVE_HIGH>;
> > +power-switch-gpio = < ASPEED_GPIO(V, 1)
> > + GPIO_ACTIVE_HIGH>;
> >  };
> >  
> >  sdhci1: sdhci@200 {
> > @@ -102,5 +123,9 @@ examples:
> >  interrupts = <26>;
> >  sdhci,auto-cmd12;
> >  clocks = < ASPEED_CLK_SDIO>;
> > +power-gpio = < ASPEED_GPIO(V, 2)
> > + GPIO_ACTIVE_HIGH>;
> > +power-switch-gpio = < ASPEED_GPIO(V, 3)
> > + GPIO_ACTIVE_HIGH>;
> >  };
> >  };
> > -- 
> > 2.17.1
> > 


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

2021-04-12 Thread Ulf Hansson
On Thu, 8 Apr 2021 at 03:52, 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.

Thanks for sharing the details, it certainly helps while reviewing.

>
> Signed-off-by: Steven Lee 
> ---
>  .../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.

>- compatible
>- reg
> @@ -80,6 +96,7 @@ required:
>  examples:
>- |
>  #include 
> +#include 
>  sdc@1e74 {
>  compatible = "aspeed,ast2500-sd-controller";
>  reg = <0x1e74 0x100>;
> @@ -94,6 +111,10 @@ examples:
>  interrupts = <26>;
>  sdhci,auto-cmd12;
>  clocks = < ASPEED_CLK_SDIO>;
> +power-gpio = < ASPEED_GPIO(V, 0)
> + GPIO_ACTIVE_HIGH>;
> +power-switch-gpio = < ASPEED_GPIO(V, 1)
> + GPIO_ACTIVE_HIGH>;
>  };
>
>  sdhci1: sdhci@200 {
> @@ -102,5 +123,9 @@ examples:
>  interrupts = <26>;
>  sdhci,auto-cmd12;
>  clocks = < ASPEED_CLK_SDIO>;
> +power-gpio = < ASPEED_GPIO(V, 2)
> + GPIO_ACTIVE_HIGH>;
> +power-switch-gpio = < ASPEED_GPIO(V, 3)
> + GPIO_ACTIVE_HIGH>;
>  };
>  };

Kind regards
Uffe


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

2021-04-09 Thread Rob Herring
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 
> ---
>  .../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.

> +description:
> +  The GPIO for enabling/disabling SD bus power.
> +maxItems: 1

blank line

> +  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:
>- compatible
>- reg
> @@ -80,6 +96,7 @@ required:
>  examples:
>- |
>  #include 
> +#include 
>  sdc@1e74 {
>  compatible = "aspeed,ast2500-sd-controller";
>  reg = <0x1e74 0x100>;
> @@ -94,6 +111,10 @@ examples:
>  interrupts = <26>;
>  sdhci,auto-cmd12;
>  clocks = < ASPEED_CLK_SDIO>;
> +power-gpio = < ASPEED_GPIO(V, 0)
> + GPIO_ACTIVE_HIGH>;
> +power-switch-gpio = < ASPEED_GPIO(V, 1)
> + GPIO_ACTIVE_HIGH>;
>  };
>  
>  sdhci1: sdhci@200 {
> @@ -102,5 +123,9 @@ examples:
>  interrupts = <26>;
>  sdhci,auto-cmd12;
>  clocks = < ASPEED_CLK_SDIO>;
> +power-gpio = < ASPEED_GPIO(V, 2)
> + GPIO_ACTIVE_HIGH>;
> +power-switch-gpio = < ASPEED_GPIO(V, 3)
> + GPIO_ACTIVE_HIGH>;
>  };
>  };
> -- 
> 2.17.1
>