Re: [PATCH 00/10] ARM, arm64: dts: renesas: Use R-Car GPIO Gen[123] fallback compat strings

[Simon Horman <horms@verge.net.au>]

On Tue, Aug 08, 2017 at 07:29:28PM +0900, Magnus Damm wrote:
> Hi Simon,
> 
> On Tue, Aug 8, 2017 at 5:39 PM, Simon Horman <horms+renesas@verge.net.au> wrote:
> > Use newly added R-Car GPIO Gen 1, 2 and 3 fallback compat strings in place
> > of now deprecated non-generation specific R-Car GPIO fallback compat string
> > in the DT of Renesas ARM and arm64 based SoCs.
> >
> > This should have no run-time effect as the driver matches against the
> > per-SoC compat string before considering the fallback compat string.
> 
> Thanks for your efforts.I have no issue with your series (apart from
> the GPIO and SATA mistake), but at the same time I believe the GPIO
> hardware itself is backwards compatible between various generations.
> 
> In the nitpick department I would like to point out that the level of
> hardware difference between say R-Car Gen1 GPIO and R-Car Gen2 GPIO is
> similar to say good old uarts like 8250 and 16450 hardware. Basically
> a couple of registers were added to the hardware in a
> backwards-compatible way if I recall correctly.
> 
> So if we are going to use "compatible" to point out if hardware is
> compatible or not then I would do this instead:

Thanks for your feedback.

When the generation specific compat strings were recently
added the renesas,gpio-rcar compat string was marked as deprecated
as I was under the understanding that it was only compatibile with gen 1 SoCs.

It now seems that was not the best thing to do and renesas,gpio-rcar should
be re-instated as being a generic fallback for all R-Car versions supported
in upstream.

Do you concur?

> 
> --- a/arch/arm64/boot/dts/renesas/r8a7796.dtsi
> +++ b/arch/arm64/boot/dts/renesas/r8a7796.dtsi
> @@ -214,7 +214,7 @@
> 
>                 gpio0: gpio@e6050000 {
>                         compatible = "renesas,gpio-r8a7796",
> +                                    "renesas,rcar-gen3-gpio";
>                                      "renesas,gpio-rcar";
>                         reg = <0 0xe6050000 0 0x50>;
>                         interrupts = <GIC_SPI 4 IRQ_TYPE_LEVEL_HIGH>;
>                         #gpio-cells = <2>;
> 
> At the same time I'm not sure if I care _that_ much. =)
> 
> Thanks,
> 
> / magnus
>