Re: [PATCH/RFC] gpio: rcar: add gen[123] fallback compatibility strings

[Geert Uytterhoeven <geert@linux-m68k.org>]

Hi Simon,

On Tue, Jul 11, 2017 at 2:38 PM, Simon Horman
<horms+renesas@verge.net.au> wrote:
> Add fallback compatibility string for R-Car Gen 1, 2 and 3.
>
> In the case of Renesas R-Car hardware we know that there are generations of
> SoCs, f.e. Gen 1 and 2. But beyond that its not clear what the relationship
> between IP blocks might be. For example, I believe that r8a7790 is older
> than r8a7791 but that doesn't imply that the latter is a descendant of the
> former or vice versa.
>
> We can, however, by examining the documentation and behaviour of the
> hardware at run-time observe that the current driver implementation appears
> to be compatible with the IP blocks on SoCs within a given generation.
>
> For the above reasons and convenience when enabling new SoCs a
> per-generation fallback compatibility string scheme being adopted for
> drivers for Renesas SoCs.
>
> Also deprecate renesas,gpio-rcar as its name is more generic than its
> implementation.
>
> Signed-off-by: Simon Horman <horms+renesas@verge.net.au>

Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>

> ---
> Based on linux-gpio/for-next
> ---
>  .../devicetree/bindings/gpio/renesas,gpio-rcar.txt        | 15 +++++++++++----
>  drivers/gpio/gpio-rcar.c                                  | 10 ++++++++++
>  2 files changed, 21 insertions(+), 4 deletions(-)
>
> diff --git a/Documentation/devicetree/bindings/gpio/renesas,gpio-rcar.txt b/Documentation/devicetree/bindings/gpio/renesas,gpio-rcar.txt
> index 6826a371fb69..48634b01f1bf 100644
> --- a/Documentation/devicetree/bindings/gpio/renesas,gpio-rcar.txt
> +++ b/Documentation/devicetree/bindings/gpio/renesas,gpio-rcar.txt
> @@ -2,7 +2,7 @@
>
>  Required Properties:
>
> -  - compatible: should contain one of the following.
> +  - compatible: should contain one or more of the following:
>      - "renesas,gpio-r8a7743": for R8A7743 (RZ/G1M) compatible GPIO controller.
>      - "renesas,gpio-r8a7778": for R8A7778 (R-Mobile M1) compatible GPIO controller.
>      - "renesas,gpio-r8a7779": for R8A7779 (R-Car H1) compatible GPIO controller.
> @@ -13,7 +13,14 @@ Required Properties:
>      - "renesas,gpio-r8a7794": for R8A7794 (R-Car E2) compatible GPIO controller.
>      - "renesas,gpio-r8a7795": for R8A7795 (R-Car H3) compatible GPIO controller.
>      - "renesas,gpio-r8a7796": for R8A7796 (R-Car M3-W) compatible GPIO controller.
> -    - "renesas,gpio-rcar": for generic R-Car GPIO controller.
> +    - "renesas,rcar-gen1-gpio": for a generic R-Car Gen1 GPIO controller.
> +    - "renesas,rcar-gen2-gpio": for a generic R-Car Gen2 or RZ/G1 GPIO controller.
> +    - "renesas,rcar-gen3-gpio": for a generic R-Car Gen3 GPIO controller.
> +    - "renesas,gpio-rcar": deprecated.
> +
> +    When compatible with the generic version nodes must list the
> +    SoC-specific version corresponding to the platform first followed by
> +    the generic version.

Besides for consistency, does it make sense to deprecate "renesas,gpio-rcar"
(which means R-Car Gen1) and introduce "renesas,rcar-gen1-gpio"?
It's not like new R-Car Gen1 SoCs will pop up anytime soon (do we want Linux
support for R-Car E1?).

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

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