Messages in this thread | | | Date | Thu, 19 Oct 2017 16:18:04 +0800 | From | icenowy@aosc ... | Subject | 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@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
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