Re: [linux-sunxi] [PATCH v2 6/8] ARM: dts: sun8i: a83t: Move mmc1 pinctrl setting to dtsi file

[icenowy]

å 2017-10-19 14:48ïChen-Yu Tsai åéï
> On Wed, Oct 18, 2017 at 11:00 PM, Joonas KylmÃlà 
> <joonas.kylmala@xxxxxx> wrote:
> > Hi,
> >
> > Chen-Yu Tsai:
> > > mmc1 only has 1 possible pinmux setting.
> >
> > What if someone is using the MMC with bus width 1 and then using the
> > remaining 3 pins for something else?
>
> 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.
>
> 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.

> ChenYu