Re: [PATCH 1/1] clk: Document of_clk_get_by_name() return values

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Medium] clk: false claim in of_clk_get_by_name() documentation
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commit d09131dbb97111f2e3801d98bcbd5fbb8288397d
Author: Dan Carpenter <error27@gmail.com>

clk: Document of_clk_get_by_name() return values

This commit documents the return values for of_clk_get_by_name(), stating
that it returns a valid clock on success or an error pointer on failure. It
also explicitly claims that the function never returns NULL.

> diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
> index fef87167a60b5..7e1a88c3837a3 100644
> --- a/drivers/clk/clk.c
> +++ b/drivers/clk/clk.c
> @@ -5420,6 +5420,9 @@ EXPORT_SYMBOL(of_clk_get);
>   * This function parses the clocks and clock-names properties,
>   * and uses them to look up the struct clk from the registered list of clock
>   * providers.
> + *
> + * Returns: A clock pointer on success or an error pointer on failure.  This
> + * function never returns NULL.
>   */
>  struct clk *of_clk_get_by_name(struct device_node *np, const char *name)
>  {

[Severity: Medium]
Is it accurate that this function never returns NULL?

It appears of_clk_get_by_name() delegates to of_clk_get_hw_from_clkspec(),
which invokes the clock provider's get_hw callback. Providers often use
of_clk_hw_onecell_get() with sparse clock arrays (such as
struct clk_hw_onecell_data) where uninitialized entries are NULL.

When such an entry is requested, NULL propagates back through
clk_hw_create_clk() (which uses ERR_CAST(NULL)), causing
of_clk_get_by_name() to return NULL on success.

Could this documentation mislead driver developers into removing NULL checks
or introducing assertions (e.g., BUG_ON(!clk)) that will crash the kernel
when a valid dummy clock is returned?

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Sashiko AI review · https://sashiko.dev/#/patchset/b3de48fdbaaade69cce126b59bd6dfb8f437b495.1789451862.git.error27@gmail.com?part=1