linux-kernel - Re: [PATCH v2 6/9] clk: renesas: rzv2h-cpg: Ignore monitoring CLK

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Message-ID: <CAMuHMdWZisqxyGL32Y-AD1UgQD9fWKG+a-o71R+KeuSqn=U6gQ@mail.gmail.com>
Date: Tue, 15 Apr 2025 16:58:12 +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>, 
	Rob Herring <robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley <conor+dt@...nel.org>, 
	Magnus Damm <magnus.damm@...il.com>, linux-renesas-soc@...r.kernel.org, 
	linux-clk@...r.kernel.org, linux-kernel@...r.kernel.org, 
	devicetree@...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 v2 6/9] clk: renesas: rzv2h-cpg: Ignore monitoring CLK_MON
 bits for external clocks

Hi Prabhakar,

On Mon, 7 Apr 2025 at 18:52, Prabhakar <prabhakar.csengg@...il.com> wrote:
> From: Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>
>
> Ignore CLK_MON bits when turning on/off module clocks that use an external
> clock source.
>
> Introduce the `DEF_MOD_EXTERNAL()` macro for defining module clocks that
> may have an external clock source. Update `rzv2h_cpg_register_mod_clk()`
> to update mon_index.
>
> Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>

> --- a/drivers/clk/renesas/rzv2h-cpg.c
> +++ b/drivers/clk/renesas/rzv2h-cpg.c
> @@ -569,6 +569,25 @@ static void rzv2h_mod_clock_mstop_disable(struct rzv2h_cpg_priv *priv,
>         spin_unlock_irqrestore(&priv->rmw_lock, flags);
>  }
>
> +static bool rzv2h_mod_clock_is_external(struct rzv2h_cpg_priv *priv,
> +                                       u16 ext_clk_offset,
> +                                       u8 ext_clk_bit,
> +                                       u8 ext_cond)
> +{
> +       u32 value;
> +
> +       if (!ext_clk_offset)
> +               return false;
> +
> +       value = readl(priv->base + ext_clk_offset) & BIT(ext_clk_bit);

As ext_clk_offset is actually the offset of the Static Mux Control
Registers (CPG_SSELm), this reads the current state of the mux.
However, can't the state be changed at runtime (despite it being named
a "static mux")?

> +       value >>= ext_clk_bit;
> +
> +       if (value == ext_cond)
> +               return true;
> +
> +       return false;
> +}
> +
>  static int rzv2h_mod_clock_is_enabled(struct clk_hw *hw)
>  {
>         struct mod_clock *clock = to_mod_clock(hw);

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