linux-kernel - Re: [PATCH v3 1/2] clk: renesas: rzv2h: Add selective Runtime PM support for clocks

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Message-ID: <CAMuHMdUbu8aR50NhChJ1Ur-GXW4eiELU=XyFAmBNPRzzA1dvKw@mail.gmail.com>
Date: Fri, 6 Dec 2024 14:09:49 +0100
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 v3 1/2] clk: renesas: rzv2h: Add selective Runtime PM
 support for clocks

On Mon, Dec 2, 2024 at 9:39 PM Prabhakar <prabhakar.csengg@...il.com> wrote:
> From: Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>
>
> Update `rzv2h_cpg_attach_dev` to prevent external and core clocks not tied
> to the power domain from being managed by Runtime PM. This ensures that
> only clocks originating from the domain are controlled, thereby avoiding
> unintended handling of external and core clocks.
>
> Additionally, introduce a `no_pm` flag in `mod_clock` and `rzv2h_mod_clk`
> structures to exclude specific clocks from Runtime PM when needed. Some
> clocks, such as those in the CRU block, require unique enable/disable
> sequences that are incompatible with standard Runtime PM. For example,
> the CSI-2 D-PHY clock initialization requires toggling individual clocks,
> making Runtime PM unsuitable.
>
> The helper function `rzv2h_cpg_is_pm_clk()` checks whether a clock should
> be managed by Runtime PM based on this `no_pm` flag. New macros, such as
> `DEF_MOD_NO_PM`, allow straightforward declaration of clocks that bypass
> PM.
>
> Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>
> ---
> v2->v3
> -> Replaced `rzv2h-cpg` to `rzv2h` in commit header
> -> Switched to use for loop while looping
> -> Considering core clocks to be non pm clocks

Reviewed-by: Geert Uytterhoeven <geert+renesas@...der.be>
i.e. will queue in renesas-clk for v6.14.

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