On Mon, Feb 15, 2016 at 10:16:50PM +0100, Geert Uytterhoeven wrote:
> The Renesas R-Car System Controller provides power management for the
> CPU cores and various coprocessors, following the generic PM domain
> bindings in Documentation/devicetree/bindings/power/power_domain.txt.
>
> This supports R-Car Gen1, Gen2, and Gen3.
>
> Signed-off-by: Geert Uytterhoeven <geert+renesas@xxxxxxxxx>
> ---
> Alternatives I considered:
>
> - Using a single node per power register block, even if it contains
> multiple domains, e.g.:
>
> pd_ca15_scu: ca15_scu@180 {
> reg = <0x180 0x20>;
> #address-cells = <1>;
> #size-cells = <0>;
> #power-domain-cells = <0>;
> renesas,interrupt-bits = <12>;
>
> pd_ca15_cpu: ca15_cpu@40 {
> reg = <0x40 0x20>;
> #power-domain-cells = <1>;
> renesas,pm-domain-indices = <0 1>;
> renesas,pm-domain-names =
> "ca15_cpu0", "ca15_cpu1";
> renesas,interrupt-bits = <0 1>;
> };
> };
>
> Notes:
> - You cannot just have a property with the number of domains, as
> index 0 is not used on R-Car H1. Hence the need for
> "renesas,pm-domain-indices" and "renesas,interrupt-bits",
> - "#power-domain-cells = <1>" for nodes with multiple domains,
> which allows typos in "power-domains = <&pd_ca15_cpu n>", using
> an invalid value of "n".
>
> - Using a linear description in DT:
> - Needs parent links for subdomains,
> - More complicated to parse (lesson learned from R-Mobile PM
> Domain support).
>
> - Keeping the power register block offset and the bit number as separate
> "reg" cells, increasing "#address-cells" from 2 to 3,
>
> - Merging the interrupt bit (which needs only 5 bits) in the other "reg"
> cell, decreasing "#address-cells" from 2 to 1.
I think I'd move to not encoding mulitple things into reg. This seems
like a bit of abuse of reg. Otherwise, I don't have much to comment on.
Rob
