linux-kernel - Re: [PATCH v3 1/9] clk: add kernel docs for struct clk

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Message-ID: <b3kfxuvkz5elhkquj7iqajcoibozsysskwvbfw7rlhvo5sebhq@5uhoib7h5dtl>
Date: Tue, 19 Aug 2025 11:27:45 +0200
From: Maxime Ripard <mripard@...nel.org>
To: Brian Masney <bmasney@...hat.com>
Cc: Michael Turquette <mturquette@...libre.com>, 
	Stephen Boyd <sboyd@...nel.org>, linux-clk@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 1/9] clk: add kernel docs for struct clk_core

Hi,

On Tue, Aug 12, 2025 at 10:40:31AM -0400, Brian Masney wrote:
> Document all of the members of struct clk_core.
> 
> Signed-off-by: Brian Masney <bmasney@...hat.com>
> ---
>  drivers/clk/clk.c | 55 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 55 insertions(+)
> 
> diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
> index b821b2cdb155331c85fafbd2fac8ab3703a08e4d..41690448ce9ada8eaa30221950da4a3b1c4552d2 100644
> --- a/drivers/clk/clk.c
> +++ b/drivers/clk/clk.c
> @@ -57,6 +57,61 @@ struct clk_parent_map {
>  	int			index;
>  };
>  
> +/**
> + * struct clk_core - This structure represents the internal state of a clk
> + * within the kernel's clock tree. Drivers do not interact with this structure
> + * directly. The clk_core is manipulated by the framework to manage clock
> + * operations, parent/child relationships, rate, and other properties.
> + *
> + * @name:              Unique name of the clk for identification.
> + * @ops:               Pointer to hardware-specific operations for this clk.
> + * @hw:                Pointer for traversing from a struct clk to its
> + *                     corresponding hardware-specific structure.
> + * @owner:             Kernel module owning this clk (for reference counting).
> + * @dev:               Device associated with this clk (optional)
> + * @rpm_node:          Node for runtime power management list management.
> + * @of_node:           Device tree node associated with this clk (if applicable)
> + * @parent:            Pointer to the current parent in the clock tree.
> + * @parents:           Array of possible parents (for muxes/selectable parents).
> + * @num_parents:       Number of possible parents
> + * @new_parent_index:  Index of the new parent during parent change.
> + * @rate:              Current clock rate (Hz). This is effectively a cached
> + *                     value of what the hardware has been programmed with. It's
> + *                     initialized by reading the value at boot time, and will
> + *                     be updated every time an operation affects the rate.
> + *                     Clocks with the CLK_GET_RATE_NOCACHE flag should not use
> + *                     this value, as its rate is expected to change behind the
> + *                     kernel's back (because the firmware might change it, for
> + *                     example). Also, if the clock is orphan, it's set to 0
> + *                     and updated when (and if) its parent is later loaded, so
> + *                     its content is only ever valid if clk_core->orphan is
> + *                     false.
> + * @req_rate:          The last rate requested by a call to clk_set_rate. It's
> + *                     initialized to clk_core->rate. It's also updated to
> + *                     clk_core->rate every time the clock is reparented, and
> + *                     when we're doing the orphan -> !orphan transition.
> + * @new_rate:          New rate to be set during a rate change operation.
> + * @new_parent:        Pointer to new parent during parent change.
> + * @new_child:         Pointer to new child during reparenting.

I think both can also be used during a rate change that affects the
parenting, right?

> + * @flags:             Clock property and capability flags.
> + * @orphan:            True if this clk is currently orphaned.
> + * @rpm_enabled:       True if runtime power management is enabled for this clk.
> + * @enable_count:      Reference count of enables.
> + * @prepare_count:     Reference count of prepares.
> + * @protect_count:     Protection reference count against disable.
> + * @min_rate:          Minimum supported clock rate (Hz).
> + * @max_rate:          Maximum supported clock rate (Hz).
> + * @accuracy:          Accuracy of the clock rate (parts per billion).
> + * @phase:             Current phase (degrees).
> + * @duty:              Current duty cycle configuration.

We should probably mention the unit here too. I assume it's in percent?

Looks good otherwise. Once fixed,
Reviewed-by: Maxime Ripard <mripard@...nel.org>

Maxime

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