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

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Message-ID: <CAMuHMdVpWxVDOXHGhRqHPTjG6_z3XVqT7ZdJGz7Axk8Rut3Lsw@mail.gmail.com>
Date: Tue, 13 May 2025 10:02:54 +0200
From: Geert Uytterhoeven <geert@...ux-m68k.org>
To: Prabhakar <prabhakar.csengg@...il.com>
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 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...

> +{
> +       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...

> +                       mon_index = -1;
> +       }
> +
> +       if (mon_index >= 0) {
>                 offset = GET_CLK_MON_OFFSET(clock->mon_index);

Dropping "clock->"...

>                 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