linux-kernel - Re: [PATCH v4 1/2] clk: renesas: rzv2h-cpg: Skip monitor checks for external clocks

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Message-ID: <CA+V-a8uLE52th_u+ODF+LEAZuS=X9WyyBGg0G6xOdH-xm+EkFQ@mail.gmail.com>
Date: Tue, 13 May 2025 09:43:36 +0100
From: "Lad, Prabhakar" <prabhakar.csengg@...il.com>
To: Geert Uytterhoeven <geert@...ux-m68k.org>
Cc: Michael Turquette <mturquette@...libre.com>, Stephen Boyd <sboyd@...nel.org>, 
	linux-renesas-soc@...r.kernel.org, linux-clk@...r.kernel.org, 
	linux-kernel@...r.kernel.org, Biju Das <biju.das.jz@...renesas.com>, 
	Fabrizio Castro <fabrizio.castro.jz@...esas.com>, 
	Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>
Subject: Re: [PATCH v4 1/2] clk: renesas: rzv2h-cpg: Skip monitor checks for
 external clocks

Hi Geert,

Thank you for the review.

On Tue, May 13, 2025 at 9:03 AM Geert Uytterhoeven <geert@...ux-m68k.org> wrote:
>
> Hi Prabhakar,
>
> On Fri, 9 May 2025 at 18:01, Prabhakar <prabhakar.csengg@...il.com> wrote:
> > From: Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>
> >
> > For module clocks whose parent mux may select an external source, bypass
> > the normal monitor (CLK_MON) register check when the external clock is
> > active. Introduce a new `ext_clk_mux_index` in `struct rzv2h_mod_clk` and
> > `struct mod_clock`, and detect the current mux index in
> > `rzv2h_mod_clock_is_enabled()` to disable monitoring if it matches the
> > external source index.
> >
> > Provide the `DEF_MOD_MUX_EXTERNAL()` macro for declaring external-source
> > module clocks, and populate the `ext_clk_mux_index` field in
> > `rzv2h_cpg_register_mod_clk()`.
> >
> > Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>
> > ---
> > v3->v4:
> > - Dropped external_clk_mux_index and external_clk and introduced
> >   ext_clk_mux_index.
> > - Updated DEF_MOD_*() macros to include ext_clk_mux_index.
> > - Added a new helper function `rzv2h_clk_mux_to_index()` to get the
> >   current mux index.
> > - Dropped IS_ERR() check for parent_clk in `rzv2h_clk_mux_to_index()`.
> > - Updated commit description to clarify the purpose of the patch.
>
> Thanks for the update!
>
> > --- a/drivers/clk/renesas/rzv2h-cpg.c
> > +++ b/drivers/clk/renesas/rzv2h-cpg.c
> > @@ -563,14 +565,38 @@ static void rzv2h_mod_clock_mstop_disable(struct rzv2h_cpg_priv *priv,
> >         spin_unlock_irqrestore(&priv->rmw_lock, flags);
> >  }
> >
> > +static int rzv2h_clk_mux_to_index(struct clk_hw *hw)
>
> Renaming to rzv2h_parent_clk_mux_to_index(), as it operates on the parent...
>
Agreed, it makes sense.

> > +{
> > +       struct clk_hw *parent_hw;
> > +       struct clk *parent_clk;
> > +       struct clk_mux *mux;
> > +       u32 val;
> > +
> > +       /* This will always succeed, so no need to check for IS_ERR() */
> > +       parent_clk = clk_get_parent(hw->clk);
> > +
> > +       parent_hw = __clk_get_hw(parent_clk);
> > +       mux = to_clk_mux(parent_hw);
> > +
> > +       val = readl(mux->reg) >> mux->shift;
> > +       val &= mux->mask;
> > +       return clk_mux_val_to_index(parent_hw, mux->table, 0, val);
> > +}
> > +
> >  static int rzv2h_mod_clock_is_enabled(struct clk_hw *hw)
> >  {
> >         struct mod_clock *clock = to_mod_clock(hw);
> >         struct rzv2h_cpg_priv *priv = clock->priv;
> > +       int mon_index = clock->mon_index;
> >         u32 bitmask;
> >         u32 offset;
> >
> > -       if (clock->mon_index >= 0) {
> > +       if (clock->ext_clk_mux_index >= 0) {
> > +               if (rzv2h_clk_mux_to_index(hw) == clock->ext_clk_mux_index)
>
> Collapsing into a single if-statement...
>
Thanks, makes sense.

> > +                       mon_index = -1;
> > +       }
> > +
> > +       if (mon_index >= 0) {
> >                 offset = GET_CLK_MON_OFFSET(clock->mon_index);
>
> Dropping "clock->"...
>
Thanks, makes sense.

Cheers,
Prabhakar

> >                 bitmask = BIT(clock->mon_bit);
> >
> >
>
> Reviewed-by: Geert Uytterhoeven <geert+renesas@...der.be>
> i.e. will queue in renesas-clk for v6.17 with the above changes.
>
> Gr{oetje,eeting}s,
>
>                         Geert
>
>
> --
> Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-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
>