[PATCH v3 0/3] Add DTS for NanoPi R2S Plus

[m.plak at icloud.com]

Hello Sergey,

On 14 Aug 2024, at 19:00, Sergey Bostandzhyan <jin at mediatomb.cc> wrote:
> here is version 3 of the NanoPi R2S Plus patchset.


Thanks! I was just experimenting with a patch for that board.


eMMC:

A close cousin of that board, the NanoPi R2C Plus, similarly adds eMMC to 
its base version, R2C.

R2C Plus is already supported by rk3328-nanopi-r2c-plus.dts.

The r2c-plus DTS file differs slightly from your patch.
Would it not be better to use the same fragment for both r2s-plus and r2c-plus? 
Or even place the eMMC activation in a shared dtsi file?


I’ve compared the two and the friendlyelec kernel (not u-boot) sources.
 your patch does not contain these lines from r2c-plus:
    vmmc-supply = <&vcc_io_33>;
    vqmmc-supply = <&vcc18_emmc>;
    mmc-ddr-1_8v;

your patch adds these lines that are not in r2c-plus:
    supports-emmc;
    disable-wp;
    num-slots = <1>;

r2c-plus has a line that is in rk3328.dtsi already:
    max-frequency = <150000000>; 

the friendlyelec kernel sources also add:
    no-sd;


From the description in the mmc-controller binding documentation, I believe
disable-wp should not be used. The description for no-sd  I find confusing.
Can't find num-slots and supports-emmc there.

The RK3288 datasheet does not mention support for DDR mode, so mmc-ddr-1_8v 
surprises me a bit. The datasheet does explicitly mention that HS400 is _not_ 
supported.


USB:

Another change with the Plus version of the R2S is that the USB 2.0 port that 
used to be wired to the ethernet chip now is used for an external USB port. 
I don’t have the hardware here (yet), so can't test if that USB 2.0 and the 
USB 3.0 work independently or need to be explicitly separated.


refs:
Documentation/devicetree/bindings/mmc/mmc-controller.yaml