[PATCH v12 1/7] arm64: renesas: r8a7795: Add Renesas R8A7795 SoC support

[Catalin Marinas]

On Thu, Oct 29, 2015 at 02:15:19PM +0900, Magnus Damm wrote:
> On Thu, Oct 29, 2015 at 3:45 AM, Catalin Marinas
> <catalin.marinas at arm.com> wrote:
> > On Mon, Oct 26, 2015 at 03:01:46PM +0900, Simon Horman wrote:
> >> --- a/arch/arm64/Kconfig.platforms
> >> +++ b/arch/arm64/Kconfig.platforms
> >> @@ -66,6 +66,23 @@ config ARCH_SEATTLE
> >>       help
> >>         This enables support for AMD Seattle SOC Family
> >>
> >> +config ARCH_SHMOBILE
> >> +     bool
> >> +
> >> +config ARCH_RENESAS
> >> +     bool "Renesas SoC Platforms"
> >> +     select ARCH_SHMOBILE
> >> +     select PINCTRL
> >> +     select PM_GENERIC_DOMAINS if PM
> >> +     help
> >> +       This enables support for the ARMv8 based Renesas SoCs.
> >> +
> >> +config ARCH_R8A7795
> >> +     bool "Renesas R-Car H3 SoC Platform"
> >> +     depends on ARCH_RENESAS
> >> +     help
> >> +       This enables support for the Renesas R-Car H3 SoC.
> >
> > Do you need such fine-grained configuration? I'd really like to avoid
> > individual SoC Kconfig entries and only include SoC families (like
> > ARCH_RENESAS). There are some which I didn't spot at the time
> > (ARCH_FSL_LS2085A and ARCH_TEGRA_132_SOC) but we shouldn't continue this
> > trend any further.
> 
> I agree with you about coarse grained configuration in general. I am
> also wondering how to handle cases where IP varies with SoC version.
> =)

The code should cope with multiple drivers built into the kernel anyway,
single Image is a hard requirement. If you want to trim down an image
for a specific SoC (production kernel), just use individual Kconfig
entries for drivers that may depend on ARCH_RENESAS but not an
ARCH_R8A7795 which is used in drivers/ Makefiles.

> The two most common cases with SoC-specific IP for Renesas SoCs tend
> to be Pinctrl which is using rather large tables to support the PFC
> hardware and also the clocks (CCF) that drives the SoC specific CPG
> hardware. For the PFC and CPG I think it makes sense to enable build
> based on SoC model like we do already, but for the Kconfig bits in
> arch/arm64 perhaps ARCH_RENESAS can simply select ARCH_R8A7795?

I'm suggesting the other way around: CONFIG_PINCTRL_R8A7795 which
depends on ARCH_RENESAS, default y. Similarly for clocks and other
drivers.

-- 
Catalin