Re: [PATCH v9 3/7] mux: add help text for MULTIPLEXER config option

[Josua Mayer <josua@solid-run.com>]

Hi Peter,

On 09/02/2026 13:10, Peter Rosin wrote:
> Hi!
>
> 2026-02-08 at 16:38, Josua Mayer wrote:
>> Add prompt and help text for CONFIG_MULTIPLEXER to allow enabling this
>> option thorugh the kernel configuration without explicit "select" driver
>> dependencies.
>>
>> Select it by default when COMPILE_TEST is set for better coverage.
>>
>> Signed-off-by: Josua Mayer <josua@solid-run.com>
>> ---
>>   drivers/mux/Kconfig | 9 ++++++++-
>>   1 file changed, 8 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/mux/Kconfig b/drivers/mux/Kconfig
>> index c68132e38138..4f7c6bb86fc6 100644
>> --- a/drivers/mux/Kconfig
>> +++ b/drivers/mux/Kconfig
>> @@ -4,7 +4,14 @@
>>   #
>>   
>>   config MULTIPLEXER
>> -	tristate
>> +	tristate "Generic Multiplexer Support"
>> +	default m if COMPILE_TEST
>> +	help
>> +	  This framework is designed to abstract multiplexer handling for
>> +	  devices via various GPIO-, MMIO/Regmap or specific multiplexer
>> +	  controller chips.
>> +
>> +	  If unsure, say no.
>>   
>>   menu "Multiplexer drivers"
>>   	depends on MULTIPLEXER
>>
> I'm not comfortable with making MULTIPLEXER a visible symbol. It is meant to
> be selected when needed (and there are a dozen or so instances). The kbuild
> docs has this on the subject:
>
> 	"In general use select only for non-visible symbols (no prompts
> 	 anywhere) and for symbols with no dependencies."
The patch description didn't make the decision logic clear,
and I plan to submit a standalone patch for this after v7.0-rc1.

Basically existing drivers using mux core used "select" to enable it,
even though the core can function standalone with device-tree.

Some of these users (phy-can-transceiver) function perfectly
perfectly fine without mux, and use it as an optional feature.

Likely drivers only used "select" to avoid writing helper functions,
prompt, kconfig description and stubs - which this patch-set added.

So I will argue that some existing users relying on "select" was wrong,
and that the mux framework is generally useful on its own.