[PATCH] PM / Domains: Restrict "samsung, power-domain" checks to ARCH_EXYNOS

[Rafael J. Wysocki]

On Fri, Oct 21, 2016 at 1:34 PM, Geert Uytterhoeven
<geert+renesas at glider.be> wrote:
> Currently the generic PM Domain code code checks for the presence of
> both (generic) "power-domains" and (Samsung Exynos legacy)
> "samsung,power-domain" properties in all device tree nodes representing
> devices.
>
> There are two issues with this:
>   1. This imposes a small boot-time penalty on all platforms using DT,
>   2. Platform-specific checks do not really belong in core framework
>      code.
>
> While moving the check from platform-agnostic code to Samsung-specific
> code is non-trivial, the runtime overhead can be restricted to kernels
> including support for 32-bit Samsung Exynos platforms.
>
> Signed-off-by: Geert Uytterhoeven <geert+renesas at glider.be>
> ---
> "samsung,power-domain" was only ever used in:
>   - arch/arm/boot/dts/exynos4415.dtsi: Unused?
>   - arch/arm/boot/dts/exynos3250.dtsi: CONFIG_ARCH_EXYNOS3
>   - arch/arm/boot/dts/exynos4.dtsi:    CONFIG_ARCH_EXYNOS4
>   - arch/arm/boot/dts/exynos4x12.dtsi: CONFIG_ARCH_EXYNOS4
>                                        exynos4212.dtsi is unused?
>   - arch/arm/boot/dts/exynos5250.dtsi: CONFIG_ARCH_EXYNOS5
>   - arch/arm/boot/dts/exynos5420.dtsi: CONFIG_ARCH_EXYNOS5
> ---
>  drivers/base/power/domain.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/base/power/domain.c b/drivers/base/power/domain.c
> index e023066e421547c5..d94d6a4b9b527108 100644
> --- a/drivers/base/power/domain.c
> +++ b/drivers/base/power/domain.c
> @@ -1853,7 +1853,8 @@ int genpd_dev_pm_attach(struct device *dev)
>         ret = of_parse_phandle_with_args(dev->of_node, "power-domains",
>                                         "#power-domain-cells", 0, &pd_args);
>         if (ret < 0) {
> -               if (ret != -ENOENT)
> +               if (ret != -ENOENT || !IS_ENABLED(CONFIG_ARCH_EXYNOS) ||

Please don't check things like CONFIG_ARCH_EXYNOS in the core.

If you need to put checks like that here, there is a design problem somewhere.

And imagine someone 5 years ahead from now looking at this code and
wondering why on Earth the check is here.

> +                   IS_ENABLED(CONFIG_64BIT))
>                         return ret;
>
>                 /*
> --

Thanks,
Rafael