From mboxrd@z Thu Jan  1 00:00:00 1970
From: icenowy-h8G6r0blFSE@public.gmane.org
Subject: Re: [PATCH v2 6/8] ARM: dts: sun8i: a83t: Move mmc1
 pinctrl setting to dtsi file
Date: Thu, 19 Oct 2017 16:18:04 +0800
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Cc: =?UTF-8?Q?Joonas_Kylm=C3=A4l=C3=A4?= <joonas.kylmala-X3B1VOXEql0@public.gmane.org>, Lee Jones <lee.jones-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>, Maxime Ripard <maxime.ripard-wi1+55ScJUtKEb57/3fJTNBPR1lH4CV8@public.gmane.org>, linux-arm-kernel <linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org>, devicetree <devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>, linux-kernel <linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>, linux-sunxi <linux-sunxi-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org>, Quentin Schulz <quentin.schulz-wi1+55ScJUtKEb57/3fJTNBPR1lH4CV8@public.gmane.org>
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=E5=9C=A8 2017-10-19 14:48=EF=BC=8CChen-Yu Tsai =E5=86=99=E9=81=93=EF=BC=9A
> On Wed, Oct 18, 2017 at 11:00 PM, Joonas Kylm=C3=A4l=C3=A4=20
> <joonas.kylmala-X3B1VOXEql0@public.gmane.org> wrote:
>> Hi,
>>=20
>> Chen-Yu Tsai:
>>> mmc1 only has 1 possible pinmux setting.
>>=20
>> What if someone is using the MMC with bus width 1 and then using the
>> remaining 3 pins for something else?
>=20
> I would very much like to see such a design. Currently the devices
> we see all follow Allwinner's reference design, with only minor
> modifications. As such, mmc1 is used exclusively for connecting
> SDIO-based WiFi modules.
>=20
> If such a radical(?) design is done, the vendor can always add
> a "mmc1-1bit-pins" setting and override the default.

I think this kind of thing happened on A13 -- the MMC2 of A13 is
8-bit, but Lichee Pi One wires it to a SD card slot (4-bit); then
the remaining 4 data lines are wired out as GPIO. (Lichee Pi's
do not like obeying reference design ;-) )

But I think a MMC/SDIO device under 1-bit mode is too slow that
maybe no one will use such a setup.

>=20
> ChenYu

--=20
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