From: Rob Herring <robh@kernel.org>
To: Axe Yang <axe.yang@mediatek.com>
Cc: AngeloGioacchino Del Regno
<angelogioacchino.delregno@collabora.com>,
Ulf Hansson <ulf.hansson@linaro.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>,
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 v8 1/3] dt-bindings: mmc: mtk-sd: extend interrupts and pinctrls properties
Date: Tue, 22 Mar 2022 11:42:01 -0500 [thread overview]
Message-ID: <Yjn8WVBdwiCrstx5@robh.at.kernel.org> (raw)
In-Reply-To: <4e7a532814510b03b74455f5a924b50a70699ca1.camel@mediatek.com>
On Tue, Mar 22, 2022 at 05:33:55PM +0800, Axe Yang wrote:
> Hello AngeloGioacchino,
>
> On Tue, 2022-03-22 at 09:42 +0100, AngeloGioacchino Del Regno wrote:
> > 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@mediatek.com>
> > > > > ---
> > > > > .../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?
>
> No, there is no particular reason.
> I just want to do the pin function switch quick and clean.
>
> The intention of pinctrl-1 is to set the most initial state of IO pins
> in UHS mode. If I don't need to adjust IO settings any longer, it is
> okay to select pinctrl-1 state instead of pinctrl-3.
> But think about this scenarios: after initial SDIO IO pins to UHS mode,
> I want to adjust some IO related properties, such as driving strength.
> And I want to keep these settings because with new driving strength,
> the signal is better. I'd rather to choose pinctrl-3 but not pinctrl-1,
> because I do not want the change be restored after next runtime resume.
The pinctrl-X properties set modes, they aren't supposed to be a state
machine.
Rob
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next prev parent reply other threads:[~2022-03-22 16:43 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-03-21 11:51 [PATCH v8 0/3] mmc: mediatek: add support for SDIO async IRQ Axe Yang
2022-03-21 11:51 ` [PATCH v8 1/3] dt-bindings: mmc: mtk-sd: extend interrupts and pinctrls properties Axe Yang
2022-03-21 23:29 ` Rob Herring
2022-03-22 1:35 ` Axe Yang
2022-03-22 8:42 ` AngeloGioacchino Del Regno
2022-03-22 9:33 ` Axe Yang
2022-03-22 16:42 ` Rob Herring [this message]
2022-03-23 3:38 ` Axe Yang
2022-03-21 11:51 ` [PATCH v8 2/3] mmc: core: Add support for SDIO wakeup interrupt Axe Yang
2022-03-21 11:51 ` [PATCH v8 3/3] mmc: mediatek: add support for SDIO eint wakup IRQ Axe Yang
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