在 2017-10-19 14:48，Chen-Yu Tsai 写道：
On Wed, Oct 18, 2017 at 11:00 PM, Joonas Kylmälä
<joonas.kylm...@iki.fi> 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
