linux-kernel - Re: [PATCH v3 2/6] mux: Add helper functions for getting optional and selected mux-state

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Message-ID: <e8b0579d-21b9-4072-857b-5afab92c42e6@solid-run.com>
Date: Mon, 29 Dec 2025 11:30:13 +0000
From: Josua Mayer <josua@...id-run.com>
To: Ulf Hansson <ulf.hansson@...aro.org>
CC: Rob Herring <robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>,
	Conor Dooley <conor+dt@...nel.org>, Geert Uytterhoeven
	<geert+renesas@...der.be>, Magnus Damm <magnus.damm@...il.com>, Wolfram Sang
	<wsa+renesas@...g-engineering.com>, Marc Kleine-Budde <mkl@...gutronix.de>,
	Vincent Mailhol <mailhol@...nel.org>, Vinod Koul <vkoul@...nel.org>, Kishon
 Vijay Abraham I <kishon@...nel.org>, Peter Rosin <peda@...ntia.se>, Aaro
 Koskinen <aaro.koskinen@....fi>, Andreas Kemnade <andreas@...nade.info>,
	Kevin Hilman <khilman@...libre.com>, Roger Quadros <rogerq@...nel.org>, Tony
 Lindgren <tony@...mide.com>, Vignesh R <vigneshr@...com>, Janusz Krzysztofik
	<jmkrzyszt@...il.com>, Andi Shyti <andi.shyti@...nel.org>, Mikhail Anikin
	<mikhail.anikin@...id-run.com>, Yazan Shhady <yazan.shhady@...id-run.com>,
	Jon Nettleton <jon@...id-run.com>, "linux-mmc@...r.kernel.org"
	<linux-mmc@...r.kernel.org>, "devicetree@...r.kernel.org"
	<devicetree@...r.kernel.org>, "linux-kernel@...r.kernel.org"
	<linux-kernel@...r.kernel.org>, "linux-renesas-soc@...r.kernel.org"
	<linux-renesas-soc@...r.kernel.org>, "linux-can@...r.kernel.org"
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Subject: Re: [PATCH v3 2/6] mux: Add helper functions for getting optional and
 selected mux-state

Am 22.12.25 um 15:47 schrieb Ulf Hansson:
> On Sun, 21 Dec 2025 at 11:38, Josua Mayer <josua@...id-run.com> wrote:
>> Hi Ulf,
>>
>> Am 17.12.25 um 14:38 schrieb Ulf Hansson:
>>> On Wed, 10 Dec 2025 at 18:39, Josua Mayer <josua@...id-run.com> wrote:
>> cut
>>
>>>>  /*
>>>>   * Using subsys_initcall instead of module_init here to try to ensure - for
>>>>   * the non-modular case - that the subsystem is initialized when mux consumers
>>>> diff --git a/include/linux/mux/consumer.h b/include/linux/mux/consumer.h
>>>> index 2e25c838f8312..a5da2e33a45c0 100644
>>>> --- a/include/linux/mux/consumer.h
>>>> +++ b/include/linux/mux/consumer.h
>>>> @@ -60,5 +60,9 @@ struct mux_control *devm_mux_control_get(struct device *dev,
>>>>                                          const char *mux_name);
>>>>  struct mux_state *devm_mux_state_get(struct device *dev,
>>>>                                      const char *mux_name);
>>>> +struct mux_state *devm_mux_state_get_optional(struct device *dev,
>>>> +                                             const char *mux_name);
>>>> +struct mux_state *devm_mux_state_get_optional_selected(struct device *dev,
>>>> +                                                      const char *mux_name);
>>> Seems like we need stub-functions of these too. Otherwise
>>> subsystems/drivers need to have a "depends on MULTIPLEXER" in their
>>> Kconfigs.
>> Currently the drivers that can use a mux select MULTIPLEXER in Kconfig.
> Yes, but that's not generally how we do this. The driver may not need
> MULTIPLEXER for all platforms that driver is being used on.
>
>> There already exist a few mux helpers both for mux-state and for mux-control,
>> and they might all need stubs.
> Correct. I think we should add subs for all of them.
>
>> I'd prefer the restructuring of kconfig dependencies being independent from
>> adding mux-state functionality to renesas sdhi driver.
> I understand your point, but adding the stubs isn't really a big thing
> - unless someone has some good arguments not to!?
>
> Moreover, since the series changes the mux-core anyways - and
> subsequent changes depend on it, I don't see an issue to fold in yet
> another patch to add the stubs.
Would this also cause changing all the Kconfig "select MULTIPLEXER"?
If it is only the stubs - sure.

And then in the renesas sdhi patch I can drop my change to kconfig.

sincerely
Josua Mayer