RE: [PATCH] arm64: dts: renesas: rzt2h-n2h-evk: Configure eMMC/SDHI pins

[Fabrizio Castro]

Hi Geert,

Thanks for your review!

> From: Geert Uytterhoeven <geert@xxxxxxxxxxxxxx>
> Sent: 22 April 2026 10:57
> To: Fabrizio Castro <fabrizio.castro.jz@xxxxxxxxxxx>
> Cc: magnus.damm <magnus.damm@xxxxxxxxx>; Rob Herring <robh@xxxxxxxxxx>; Krzysztof Kozlowski
> <krzk+dt@xxxxxxxxxx>; Conor Dooley <conor+dt@xxxxxxxxxx>; linux-renesas-soc@xxxxxxxxxxxxxxx;
> devicetree@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; Biju Das <biju.das.jz@xxxxxxxxxxxxxx>;
> Prabhakar Mahadev Lad <prabhakar.mahadev-lad.rj@xxxxxxxxxxxxxx>
> Subject: Re: [PATCH] arm64: dts: renesas: rzt2h-n2h-evk: Configure eMMC/SDHI pins
> 
> Hi Fabrizio,
> 
> On Tue, 31 Mar 2026 at 16:52, Fabrizio Castro
> <fabrizio.castro.jz@xxxxxxxxxxx> wrote:
> > The HW user manual for the Renesas RZ/T2H and the RZ/N2H state
> > that for SDR104, SDR50, and HS200 to work properly the eMMC/SDHI
> > interface pins have to be configured as specified below:
> > * SDn_CLK pin - drive strength: Ultra High, slew rate: fast
> > * Other SDn_* pins: drive strength: High, slew rate: fast,
> >   Schmitt trigger: disabled (not applicable to SDn_RST pins).
> >
> > Adjust the pin definitions accordingly.
> >
> > Signed-off-by: Fabrizio Castro <fabrizio.castro.jz@xxxxxxxxxxx>
> 
> According to Table 58.11 ("IO setting (DRCTLm register setting)
> condition"), the recommended drive strength value for the SDn_CLK pins
> depends on the transfer mode. So shouldn't this be changed at runtime,
> depending on the type of SD card that is present, using different
> pinctrl states?

You are totally right. Also, other pins will need adjusting as well.

I'll send a v2 shortly.

Cheers,
Fab

> 
> Currently we have:
> 
>     &sdhi0 {
>             pinctrl-0 = <&sdhi0_sd_pins>;
>             pinctrl-1 = <&sdhi0_sd_pins>;
>             pinctrl-names = "default", "state_uhs";
>             ...
>     };
> 
> I.e. it uses the same pinctrl state for all modes.
> 
> Gr{oetje,eeting}s,
> 
>                         Geert
> 
> --
> Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx
> 
> In personal conversations with technical people, I call myself a hacker. But
> when I'm talking to journalists I just say "programmer" or something like that.
>                                 -- Linus Torvalds