linux-kernel - Re: [PATCH v3 4/4] mux: gpio-mux: add adi,adg2404 support

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Message-ID: <eb7acb38-8993-4203-a13d-7e5be4b9c6ec@kernel.org>
Date: Fri, 16 Jan 2026 11:42:27 +0100
From: Krzysztof Kozlowski <krzk@...nel.org>
To: "Miclaus, Antoniu" <Antoniu.Miclaus@...log.com>
Cc: Peter Rosin <peda@...ntia.se>, Rob Herring <robh@...nel.org>,
 Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley
 <conor+dt@...nel.org>, Srinivas Kandagatla <srini@...nel.org>,
 Johan Hovold <johan+linaro@...nel.org>,
 Bartosz Golaszewski <bartosz.golaszewski@...aro.org>,
 Linus Walleij <linus.walleij@...aro.org>,
 David Lechner <dlechner@...libre.com>,
 "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
 "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v3 4/4] mux: gpio-mux: add adi,adg2404 support

On 16/01/2026 10:48, Miclaus, Antoniu wrote:
>> -----Original Message-----
>> From: Krzysztof Kozlowski <krzk@...nel.org>
>> Sent: Friday, January 16, 2026 10:33 AM
>> To: Miclaus, Antoniu <Antoniu.Miclaus@...log.com>
>> Cc: Peter Rosin <peda@...ntia.se>; Rob Herring <robh@...nel.org>; Krzysztof
>> Kozlowski <krzk+dt@...nel.org>; Conor Dooley <conor+dt@...nel.org>;
>> Srinivas Kandagatla <srini@...nel.org>; Johan Hovold
>> <johan+linaro@...nel.org>; Bartosz Golaszewski
>> <bartosz.golaszewski@...aro.org>; Linus Walleij <linus.walleij@...aro.org>;
>> David Lechner <dlechner@...libre.com>; devicetree@...r.kernel.org; linux-
>> kernel@...r.kernel.org
>> Subject: Re: [PATCH v3 4/4] mux: gpio-mux: add adi,adg2404 support
>>
>> [External]
>>
>> On Thu, Jan 15, 2026 at 02:18:22PM +0200, Antoniu Miclaus wrote:
>>> Add adi,adg2404 to the compatible list. The ADG2404 is a 4:1 analog
>>> multiplexer that benefits from the enable GPIO support to prevent
>>> glitches during channel transitions.
>>>
>>> Signed-off-by: Antoniu Miclaus <antoniu.miclaus@...log.com>
>>> ---
>>> changes in v3:
>>>  * integrate with gpio-mux driver instead of standalone adg2404 driver
>>> ---
>>>  drivers/mux/gpio.c | 1 +
>>>  1 file changed, 1 insertion(+)
>>>
>>> diff --git a/drivers/mux/gpio.c b/drivers/mux/gpio.c
>>> index 93487483e81f..bd8f0c617dd6 100644
>>> --- a/drivers/mux/gpio.c
>>> +++ b/drivers/mux/gpio.c
>>> @@ -59,6 +59,7 @@ static const struct mux_control_ops mux_gpio_ops = {
>>>
>>>  static const struct of_device_id mux_gpio_dt_ids[] = {
>>>  	{ .compatible = "gpio-mux", },
>>> +	{ .compatible = "adi,adg2404", },
>>
>> Why do you need the compatible? I do not understand this patchset. You
>> are saying you integrate it into gpio-mux, but what you did is to
>> duplicate the compatible and binding.
>>
>> Half of your patches are not necessary, you only needed to add
>> enable-gpios to gpio-mux with argument that ADG2404 can use such binding
>> (in complete/full/proper way).
> 
> I am a bit confused on how can I emphasize to the users explicitly:
> "Hey, you can use adg2404 directly with gpio-mux"
> The same issue I had with adg1712 series which can be used straight away with gpio-mux.
> If there are people/customers looking for adg2404/adg1712 there should be a hint somewhere.


This is a bit different problem. Why would we care about message to
customers? Following such approach this driver and dozen of others might
have soon 1000 entries for every possible device which is supported by it.

IMO the best way is to submit good DTS using this with a comment that it
IS ADG-foobar which also has other benefits - helps reviewing of
bindings and driver. I would accept also a short/concise list of device
names/models in the binding description.

Best regards,
Krzysztof