[PATCH v4 1/8] clk: renesas: r8a78000: Add clk_hw to clk_map

[Geert Uytterhoeven]

Hi Laurent,

On Mon, 19 Oct 2026 at 18:14, Laurent Pinchart
<laurent.pinchart at ideasonboard.com> wrote:
> On Mon, Oct 19, 2026 at 06:22:04PM +0300, Laurent Pinchart wrote:
> > On Mon, Oct 19, 2026 at 04:56:28PM +0200, Geert Uytterhoeven wrote:
> > > On Mon, 19 Oct 2026 at 16:42, Laurent Pinchart wrote:
> > > > On Fri, Oct 16, 2026 at 05:55:40PM +0200, Geert Uytterhoeven wrote:
> > > > > Prepare for mapping to other than fixed-rate clocks by adding a clk_hw
> > > > > pointer to the clk_map structure, and populating it up-front.
> > > > >
> > > > > Move r8a78000_cpg_priv.fixed_hws into fill_clk_map(), as it is no longer
> > > > > needed afterwards, and drop NUM_FIXED_CLKS.
> > > > >
> > > > > Signed-off-by: Geert Uytterhoeven <geert+renesas at glider.be>
> > >
> > > > > --- a/drivers/clk/renesas/r8a78000-cpg.c
> > > > > +++ b/drivers/clk/renesas/r8a78000-cpg.c
> > > > > @@ -16,19 +16,24 @@
> > > > >
> > > > >  #include <dt-bindings/clock/renesas,r8a78000-cpg.h>
> > > > >
> > > > > +struct clk_map_in {
> > > >
> > > > The "_in" suffix isn't very explicit.
> > >
> > > I can add a comment...
> >
> > How about calling it clk_id_map ?
> >
> > > > > +     int dt_id;              /* DT binding clock ID or -1 sentinel */
> > > > > +     u32 fw_id;              /* FIXED_CLK() ID */
> > > > > +};
> > > > > +
> > > > >  struct clk_map {
> > > > >       int dt_id;              /* DT binding clock ID or -1 sentinel */
> > > > >       u32 fw_id;              /* FIXED_CLK() ID */
> > >
> > > BTW, do you think it would be worthwhile to reuse clk_map_in here?
> >
> > Possibly. I was about to recommend just using a single structure and
> > leaving the clk_hw pointer NULL and unused in .rodata, but the memory
> > waste isn't very nice, especially if we end up with many entries :-(
>
> Actually, you could even turns clk_map into
>
> struct clk_map {
>         const struct clk_id_map *map;
>         struct clk_hw *hw;
> };
>
> It should consume the same amount of space on 64-bit platforms. Doing
> the same in the MDLC driver would save space.
>
> Or, if you want to save more memory, you could drop clk_map and store
> the clk_hw in a separate array in r8a78000_cpg_priv, using the same
> indices as clk_map_id.
>
> struct r8a78000_cpg_priv {
>         struct device *dev;
>
>         const struct clk_id_map *map;
>         unsigned int num_map_entries;
>         struct clk_hw **clks;
>
>         struct clk_hw *fixed_hws[NUM_FIXED_CLKS];
> };
>
> where clks is a dynamically-allocated array fo struct clk_hw pointers,
> having the same size as the map array.

IIRC, I considered that option, but rejected it, as I still hoped to
put the (at that time multiple, per version) tables in __initconst,
so they had to be allocated and copied anyway...

> Too many options.

Hehe...

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert at linux-m68k.org

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