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

From: Axe Yang <axe.yang@mediatek.com>
To: Ulf Hansson <ulf.hansson@linaro.org>
Cc: Rob Herring <robh+dt@kernel.org>,
	Chaotian Jing <chaotian.jing@mediatek.com>,
	Matthias Brugger <matthias.bgg@gmail.com>,
	Adrian Hunter <adrian.hunter@intel.com>,
	Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>,
	Satya Tangirala <satyat@google.com>,
	Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
	Wolfram Sang <wsa+renesas@sang-engineering.com>,
	Lucas Stach <dev@lynxeye.de>,
	"Eric Biggers" <ebiggers@google.com>,
	Andrew Jeffery <andrew@aj.id.au>,
	"Stephen Boyd" <swboyd@chromium.org>,
	Kiwoong Kim <kwmad.kim@samsung.com>, Yue Hu <huyue2@yulong.com>,
	Tian Tao <tiantao6@hisilicon.com>,
	<angelogioacchino.delregno@collabora.com>,
	<linux-mmc@vger.kernel.org>, <devicetree@vger.kernel.org>,
	<linux-kernel@vger.kernel.org>,
	<linux-arm-kernel@lists.infradead.org>,
	<linux-mediatek@lists.infradead.org>
Subject: Re: [PATCH v4 1/3] dt-bindings: mmc: add cap-sdio-async-irq flag
Date: Mon, 21 Feb 2022 15:04:31 +0800	[thread overview]
Message-ID: <21fa48195101b91c09b266f1c4f40eda5d127fdb.camel@mediatek.com> (raw)
In-Reply-To: <CAPDyKFr8bV+1uTbuhMObvORLGJHsvZHUONJkdY54MXPPRWL5Qw@mail.gmail.com>

On Mon, 2022-02-14 at 16:23 +0100, Ulf Hansson wrote:
> On Wed, 19 Jan 2022 at 11:32, Axe Yang <axe.yang@mediatek.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@mediatek.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.