Re: [PATCH 1/4] gpio: add a way to parse a GPIO now and request it later

[Mehmet Fide <mehmet.fide@gmail.com>]

Hi Simon,

On 2026-09-10 Simon Glass wrote:
> I like this approach. BTW clocks and reset lines have the same problem
> so we could deal with those late as needed.

Yes, the same two-phase shape fits them; I kept this series to GPIOs to
get the pattern agreed first.

> The original index is dropped: gpio_request_by_name() passes 'index >
> 0' to gpio_request_tail() so the request label gains an index suffix
> when index != 0

You are right. The three callers converted in patch 2 all use index 0,
so I never stored it, and the test happened to work because it only
checks the function, not the label. v2 stores the index in the struct
and passes it to gpio_request_tail() with add_index = index > 0, so
both entry points produce the same label, and the test asserts the
label through gpio_get_function()'s name pointer.

> Note that list_name is a pointer with an implicit 'must outlive the
> desc' contract

Will document. All current callers pass string literals.

> Also gpio_dt_desc reads as a peer of gpio_desc when it is really a
> pending/parsed version of one. gpio_desc_parsed, or gpio_dt_spec,
> would make the two-phase relationship clearer. What do you think?

gpio_dt_spec, then: it says what the thing is (a devicetree
specification of a GPIO) rather than what it is not, and Zephyr uses
the same name for the same idea, a GPIO described by the devicetree
and configured later.

> Please note in the kernel-doc that the -ENOENT return for a
> not-present @dt is deliberate, so a caller with an optional GPIO can
> skip the 'if (dt->present)' check and just tolerate -ENOENT

Will do, and patch 2 will use that contract instead of guarding on
present in two places (see the reply there).

> Please add a gpio_get_function() check between the parse and
> the request, mirroring what patch 4 does for the regulator.

Yes. test2-gpios index 1 is a4, so the test will assert GPIOF_UNUSED on
a4 after the parse and GPIOF_OUTPUT with the expected label after the
request.

Regards,
Mehmet