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

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在 2017-10-19 14:48,Chen-Yu Tsai 写道:
On Wed, Oct 18, 2017 at 11:00 PM, Joonas Kylmälä <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
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