Re: [RFC PATCH v3 25/35] Documentation/devicetree/bindings/sh/cpus.yaml: Add SH CPU.

> On Oct 25, 2023, at 21:17, Geert Uytterhoeven <[email protected]> wrote:
> 
> Hi Jeff,
> 
> On Wed, Oct 25, 2023 at 2:10 PM D. Jeff Dionne <[email protected]> wrote:
>> On Oct 25, 2023, at 21:04, Geert Uytterhoeven <[email protected]> wrote:
>>> On Wed, Oct 25, 2023 at 1:33 PM D. Jeff Dionne <[email protected]> wrote:
>>>>> On Oct 25, 2023, at 20:14, Yoshinori Sato <[email protected]> wrote:
>>>>> On Wed, 18 Oct 2023 23:27:43 +0900,
>>>>> Geert Uytterhoeven wrote:
>>>>>> On Sat, Oct 14, 2023 at 4:54 PM Yoshinori Sato
>>>>>> <[email protected]> wrote:
>>>>>>> Renesas SuperH binding definition.
>>>>>>> 
>>>>>>> Signed-off-by: Yoshinori Sato <[email protected]>
>>> 
>>>>>>> --- /dev/null
>>>>>>> +++ b/Documentation/devicetree/bindings/sh/cpus.yaml
> 
>>>>>>> +properties:
>>>>>>> +  compatible:
>>>>>>> +    items:
>>>>>>> +      - enum:
>>>>>> 
>>>>>> Missing
>>>>>> 
>>>>>>  - jcore,j2
>>> 
>>>> We must not imply that Renesas is responsible for J2, or that it is a sanctioned SH core.
>>> 
>>> Compatible values do not declare any such endorsement.
>>> 
>>>> J-Core has the responsibility for maintenance of those SH ISA compatible cores.
>>> 
>>> The question is: does J2 implement the same instruction set as SH2,
>>> i.e. can it run unmodified SH2 code?
>> 
>> It can run all SH2 code, but an SH2 cannot run all J2 code.
> 
> This is exactly what
> 
>    compatible = "jcore,j2", "renesas,sh2";

Oh, yes.  I agree, this is correct.  Once this is settled upon, we can change new J2 cores so they will export their ROM device tree with the sh2 fallback.

Down thread, Sato-san proposes “renesas,sh4”, “renesas,sh”  I’m not sure I understand what a “renesas,sh” base fallback is.

J.

> represents.
> Cfr. Section 2.3.1 ("compatible") of the Devicetree Specification
> https://www.devicetree.org/specifications
> 
> Gr{oetje,eeting}s,
> 
>                        Geert
> 
> -- 
> Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- [email protected]
> 
> 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