linux-kernel - Re: [PATCH v4 1/3] dt-bindings: mmc: add cap-sdio-async-irq flag

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Message-ID: <21fa48195101b91c09b266f1c4f40eda5d127fdb.camel@mediatek.com>
Date:   Mon, 21 Feb 2022 15:04:31 +0800
From:   Axe Yang <axe.yang@...iatek.com>
To:     Ulf Hansson <ulf.hansson@...aro.org>
CC:     Rob Herring <robh+dt@...nel.org>,
        Chaotian Jing <chaotian.jing@...iatek.com>,
        Matthias Brugger <matthias.bgg@...il.com>,
        Adrian Hunter <adrian.hunter@...el.com>,
        Yoshihiro Shimoda <yoshihiro.shimoda.uh@...esas.com>,
        Satya Tangirala <satyat@...gle.com>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Wolfram Sang <wsa+renesas@...g-engineering.com>,
        Lucas Stach <dev@...xeye.de>,
        "Eric Biggers" <ebiggers@...gle.com>,
        Andrew Jeffery <andrew@...id.au>,
        "Stephen Boyd" <swboyd@...omium.org>,
        Kiwoong Kim <kwmad.kim@...sung.com>,
        Yue Hu <huyue2@...ong.com>, Tian Tao <tiantao6@...ilicon.com>,
        <angelogioacchino.delregno@...labora.com>,
        <linux-mmc@...r.kernel.org>, <devicetree@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-mediatek@...ts.infradead.org>
Subject: Re: [PATCH v4 1/3] dt-bindings: mmc: add cap-sdio-async-irq flag

On Mon, 2022-02-14 at 16:23 +0100, Ulf Hansson wrote:
> On Wed, 19 Jan 2022 at 11:32, Axe Yang <axe.yang@...iatek.com> wrote:
> > 
> > Asynchronous interrupt is a mechanism that allow SDIO devices alarm
> > interrupt when host stop providing clock to card. Add a DT flag to
> > enable this feature if it is supported by SDIO card.
> > 
> > Signed-off-by: Axe Yang <axe.yang@...iatek.com>
> > ---
> >  Documentation/devicetree/bindings/mmc/mmc-controller.yaml | 5
> > +++++
> >  1 file changed, 5 insertions(+)
> > 
> > diff --git a/Documentation/devicetree/bindings/mmc/mmc-
> > controller.yaml b/Documentation/devicetree/bindings/mmc/mmc-
> > controller.yaml
> > index 513f3c8758aa..16fb06f88471 100644
> > --- a/Documentation/devicetree/bindings/mmc/mmc-controller.yaml
> > +++ b/Documentation/devicetree/bindings/mmc/mmc-controller.yaml
> > @@ -165,6 +165,11 @@ properties:
> >      description:
> >        eMMC hardware reset is supported
> > 
> > +  cap-sdio-async-irq:
> > +    $ref: /schemas/types.yaml#/definitions/flag
> > +    description:
> > +      SDIO async interrupt is supported.
> 
> We already have a DT property for this, I believe.
> 
> "wakeup-source" is probably what you want, but we have additional
> properties that are related to this too. See more below.
> 
> > +
> >    cap-sdio-irq:
> >      $ref: /schemas/types.yaml#/definitions/flag
> >      description:
> 
> The above, "cap-sdio-irq", informs whether the SDIO IRQs can be
> supported at all, by the host controller.
> 
> The property "keep-power-in-suspend" informs whether we can preserve
> the power to the card during a suspend/resume cycle. This should be
> needed in your case too, I think.
> 
> In other words, you may need to combine "cap-sdio-irq",
> "wakeup-source" and "keep-power-in-suspend" to describe your HW.
> 
> However, what perhaps is missing, is a common MMC/SDIO binding that
> let us describe an optional irq-line, which sometimes is being used
> for the wakeup irq. In the sdhci-omap case, we look for an irq
> mapping
> towards "wakeup" if specified in the "interrupt-names" property.
> 
> In some case, when the SDIO card supports an out-of-band IRQ line,
> the
> similar should be specified in the child-node corresponding to the
> SDIO card.
> 
> 

Yes, the intention of the patchset is to wakeup SDIO host in
runtime/system suspend state within SDIO DAT1(in-band wakeup).

I will implement it with "wakeup-source", thanks for your review.