Re: [PATCH] spi: sh-msiof: Enforce fixed DTDL for R-Car H3

[Wolfram Sang <wsa+renesas@sang-engineering.com>]

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Hi Geert,

> > Documentation says only DTDL of 200 is allowed for this SoC.
> 
> Do you have a pointer to that?

Yes: Gen3 docs Rev.2.30 from Aug 2021, Section 59.2.1, Bits 22-20:

"[R-Car H3, R-Car H3-N]
010: 2-clock-cycle delay
Other than above: Setting prohibited"

> We already have "renesas,dtdl" to configure this from DT.
> Iff this is really needed, perhaps it should be added to r8a77951.dtsi?

I have to disagree here. The docs say that other values are prohibited.
IMO the driver should take care of valid values then. We should not rely
on user provided input.

> I suspect this is a leftover in the BSP from attempts to get MSIOF
> working on R-Car H3 ES1.0 (which it never did for me, as CLK starts
> and stops too soon, compared to MOSI/MISO).
> On R-Car H3 ES2.0, everything works fine, without touching DTDL.

The BSP originally has this patch for ES3 only. I extended to ES2 as
well because that is what the docs say.

Happy hacking,

   Wolfram


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