Re: [PATCH v3 4/5] clk: renesas: rzv2h-cpg: Extract PLL calculation math into a library

[Geert Uytterhoeven]

Hi Prabhakar,

On Mon, 15 Jun 2026 at 12:48, Prabhakar <prabhakar.csengg@xxxxxxxxx> wrote:
> From: Lad Prabhakar <prabhakar.mahadev-lad.rj@xxxxxxxxxxxxxx>
>
> Move the common PLL and divider parameter calculation logic from the
> core rzv2h-cpg driver into a standalone library file.
>
> Introduce the CLK_RZV2H_CPG_LIB Kconfig configuration symbol and create
> rzv2h-cpg-lib.c to house rzv2h_cpg_get_pll_pars() and
> rzv2h_cpg_get_pll_divs_pars().
>
> Keep rzv2h_get_pll_pars() and rzv2h_get_pll_divs_pars() in the original
> driver as wrappers that call into the new library helper endpoints.
> These wrappers are maintained for this cycle because they are actively
> referenced by the DSI driver; they will be safely removed in a subsequent
> cycle once the DSI driver is updated to use the new APIs from the library,
> preventing cross-subsystem build breakages.
>
> This restructuring allows other Renesas SoC clock drivers, such as the
> upcoming RZ/T2H and RZ/N2H platforms that utilize similar LCDC clock
> divider mathematical logic, to share the iterative calculation helper
> infrastructure without duplication.
>
> Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@xxxxxxxxxxxxxx>

Thanks for your patch!

> --- a/include/linux/clk/renesas.h
> +++ b/include/linux/clk/renesas.h
> @@ -213,4 +213,27 @@ static inline bool rzv2h_get_pll_divs_pars(const struct rzv2h_pll_limits *limits
>  }
>  #endif
>
> +#ifdef CONFIG_CLK_RZV2H_CPG_LIB
> +bool rzv2h_cpg_get_pll_pars(const struct rzv2h_pll_limits *limits,
> +                           struct rzv2h_pll_pars *pars, u64 freq_millihz);
> +
> +bool rzv2h_cpg_get_pll_divs_pars(const struct rzv2h_pll_limits *limits,
> +                                struct rzv2h_pll_div_pars *pars,
> +                                const u8 *table, u8 table_size, u64 freq_millihz);
> +#else
> +static inline bool rzv2h_cpg_get_pll_pars(const struct rzv2h_pll_limits *limits,
> +                                         struct rzv2h_pll_pars *pars,
> +                                         u64 freq_millihz)
> +{
> +       return false;
> +}
> +
> +static inline bool rzv2h_cpg_get_pll_divs_pars(const struct rzv2h_pll_limits *limits,
> +                                              struct rzv2h_pll_div_pars *pars,
> +                                              const u8 *table, u8 table_size,
> +                                              u64 freq_millihz)
> +{
> +       return false;
> +}
> +#endif
>  #endif

What about just dropping the old functions, and adding two simple
compatibility defines in the header file:

    #define rzv2h_get_pll_pars rzv2h_cpg_get_pll_pars
    #define rzv2h_get_pll_divs_pars rzv2h_cpg_get_pll_divs_pars

That way there is less code to change in the next phase.

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx

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