linux-kernel - Re: [PATCH 2/3] ARM: dts: sun5i: Add port E pinmux settings for mmc2

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Date:   Thu, 20 Apr 2023 20:13:21 +0100
From:   Jonathan McDowell <noodles@...th.li>
To:     Andre Przywara <andre.przywara@....com>
Cc:     Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Chen-Yu Tsai <wens@...e.org>,
        Jernej Skrabec <jernej.skrabec@...il.com>,
        Samuel Holland <samuel@...lland.org>,
        devicetree@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-sunxi@...ts.linux.dev, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/3] ARM: dts: sun5i: Add port E pinmux settings for mmc2

On Sun, Apr 16, 2023 at 01:47:56AM +0100, Andre Przywara wrote:
> On Sat, 15 Apr 2023 18:46:24 +0100
> Jonathan McDowell <noodles@...th.li> wrote:
> 
> Hi,
> 
> > These alternate pins for mmc2 are brought out to the 40 pin U14 header
> > on the C.H.I.P and can be used to add an external MMC device with a 4
> > bit interface. See
> > 
> > https://byteporter.com/ntc-chip-micro-sd-slot/
> > 
> > for further details on how.
> > 
> > Signed-off-by: Jonathan McDowell <noodles@...th.li>
> > ---
> >  arch/arm/boot/dts/sun5i.dtsi | 8 ++++++++
> >  1 file changed, 8 insertions(+)
> > 
> > diff --git a/arch/arm/boot/dts/sun5i.dtsi b/arch/arm/boot/dts/sun5i.dtsi
> > index 250d6b87ab4d..e4922506ce22 100644
> > --- a/arch/arm/boot/dts/sun5i.dtsi
> > +++ b/arch/arm/boot/dts/sun5i.dtsi
> > @@ -517,6 +517,14 @@ mmc2_4bit_pc_pins: mmc2-4bit-pc-pins {
> >  				bias-pull-up;
> >  			};
> > 
> 
> As this seems to be a highly non-standard and rare modification, that
> doesn't even get used in the mainline DT, please add a:
> 			/omit-if-no-ref/
> line, so we don't get this into every sun5i board.

Neat, will add in v2.

> Otherwise looks good, though I don't know if that should belong into
> the same DT overlay that is probably used to also enable the MMC2 node.

I pondered that, but we already have the mmc2-4bit-pc-pins definition
here so it seemed helpful to add the pe-pins too.

> > +			mmc2_4bit_pe_pins: mmc2-4bit-pe-pins {
> > +				pins = "PE4", "PE5", "PE6", "PE7",
> > +				       "PE8", "PE9";
> > +				function = "mmc2";
> > +				drive-strength = <30>;
> > +				bias-pull-up;
> > +			};
> > +
> >  			mmc2_8bit_pins: mmc2-8bit-pins {
> >  				pins = "PC6", "PC7", "PC8", "PC9",
> >  				       "PC10", "PC11", "PC12", "PC13",
> 

J.

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