Re: [PATCH v8 1/3] dt-bindings: mmc: mtk-sd: extend interrupts and pinctrls properties

[AngeloGioacchino Del Regno]

Il 22/03/22 02:35, Axe Yang ha scritto:
> On Mon, 2022-03-21 at 18:29 -0500, Rob Herring wrote:
> > On Mon, Mar 21, 2022 at 07:51:32PM +0800, Axe Yang wrote:
> > > Extend interrupts and pinctrls for SDIO wakeup interrupt feature.
> > > This feature allow SDIO devices alarm asynchronous interrupt to
> > > host
> > > even when host stop providing clock to SDIO card. An extra wakeup
> > > interrupt and pinctrl states for SDIO DAT1 pin state switching are
> > > required in this scenario.
> > >
> > > Signed-off-by: Axe Yang <axe.yang@xxxxxxxxxxxx>
> > > ---
> > >   .../devicetree/bindings/mmc/mtk-sd.yaml       | 23
> > > ++++++++++++++++++-
> > >   1 file changed, 22 insertions(+), 1 deletion(-)
> > >
> > > diff --git a/Documentation/devicetree/bindings/mmc/mtk-sd.yaml
> > > b/Documentation/devicetree/bindings/mmc/mtk-sd.yaml
> > > index 297ada03e3de..f57774535a1d 100644
> > > --- a/Documentation/devicetree/bindings/mmc/mtk-sd.yaml
> > > +++ b/Documentation/devicetree/bindings/mmc/mtk-sd.yaml
> > > @@ -69,12 +69,23 @@ properties:
> > >         - const: ahb_cg
> > >   
> > >     interrupts:
> > > -    maxItems: 1
> > > +    description:
> > > +      Should at least contain MSDC GIC interrupt. To support SDIO
> > > in-band wakeup, an extended
> > > +      interrupt is required and be configured as wakeup source
> > > irq.
> > > +    minItems: 1
> > > +    maxItems: 2
> > >   
> > >     pinctrl-names:
> > > +    description:
> > > +      Should at least contain default and state_uhs. To support
> > > SDIO in-band wakeup, dat1 pin
> > > +      will be switched between GPIO mode and SDIO DAT1 mode,
> > > state_eint and state_dat1 are
> > > +      mandatory in this scenarios.
> > > +    minItems: 2
> > >       items:
> > >         - const: default
> > >         - const: state_uhs
> > > +      - const: state_eint
> > > +      - const: state_dat1
> > >   
> > >     pinctrl-0:
> > >       description:
> > > @@ -86,6 +97,16 @@ properties:
> > >         should contain uhs mode pin ctrl.
> > >       maxItems: 1
> > >   
> > > +  pinctrl-2:
> > > +    description:
> > > +      should switch dat1 pin to GPIO mode.
> > > +    maxItems: 1
> > > +
> > > +  pinctrl-3:
> > > +    description:
> > > +      should switch SDIO dat1 pin from GPIO mode back to SDIO
> > > mode.
> >
> > How is this different than pinctrl-0?
>
> pinctrl-0 contains default settings for all IO pins(CLK/CMD/DAT).
> pinctrl-1 contains settings for all IO pins(CLK/CMD/DAT) in UHS mode.
> pinctrl-3 is lightweight pinctrl-1, only keep SDIO DAT1 pin function
> switch part.

Is there any particular reason why we cannot simply select pinctrl-1 again
instead of pinctrl-3, apart from the virtually not existent overhead of
one more mmio write?

> ...
>
> Regards,
> Axe