Re: [RFC PATCH v2 1/2] devicetree: bindings: mux: reg-mux: Update bindings for reg-mux for new property

["Vankar, Chintan" <c-vankar@ti.com>]

Hello Rob,

On 3/6/2025 3:44 AM, Rob Herring wrote:
> On Wed, Mar 5, 2025 at 3:43 PM Vankar, Chintan <c-vankar@ti.com> wrote:
>>
>> Hello Rob,
>>
>> On 3/5/2025 2:10 AM, Rob Herring wrote:
>>> On Tue, Mar 4, 2025 at 1:03 PM Vankar, Chintan <c-vankar@ti.com> wrote:
>>>>
>>>> Hello Rob,
>>>>
>>>> On 3/4/2025 9:09 PM, Rob Herring wrote:
>>>>> On Tue, Mar 04, 2025 at 03:53:05PM +0530, Chintan Vankar wrote:
>>>>>> DT-binding of reg-mux is defined in such a way that one need to provide
>>>>>> register offset and mask in a "mux-reg-masks" property and corresponding
>>>>>> register value in "idle-states" property. This constraint forces to define
>>>>>> these values in such a way that "mux-reg-masks" and "idle-states" must be
>>>>>> in sync with each other. This implementation would be more complex if
>>>>>> specific register or set of registers need to be configured which has
>>>>>> large memory space. Introduce a new property "mux-reg-masks-state" which
>>>>>> allow to specify offset, mask and value as a tuple in a single property.
>>>>>
>>>>> Maybe in hindsight that would have been better, but having 2 ways to
>>>>> specify the same thing that we have to maintain forever is not an
>>>>> improvement.
>>>>>
>>>>> No one is making you use this binding. If you have a large number of
>>>>> muxes, then maybe you should use a specific binding.
>>>>>
>>>>
>>>> Thank you for reviewing the patch. The reason behind choosing mux
>>>> subsystem is working and implementation of mmio driver. As we can see
>>>> that implementing this new property in mux-controller is almost
>>>> identical to mmio driver, and it would make it easier to define and
>>>> extend mux-controller's functionality. If we introduce the new driver
>>>> than that would be most likely a clone of mmio driver.
>>>
>>> I'm talking about the binding, not the driver. They are independent.
>>> Generic drivers are great. I love them. Generic bindings, not so much.
>>>
>>>> Let me know if implementation would be accepted by adding a new
>>>> compatible for it.
>>>
>>> Adding a new compatible to the mmio driver? Certainly. That happens
>>> all the time.
>>>
>>> I also didn't say don't use this binding as-is. That's fine too.
>>>
>>
>> Can you please review the following binding:
>>
>> oneOf:
>>     - required: [ mux-reg-masks ]
>>     - required: [ mux-reg-masks-state ]
>>
>> allOf:
>>     - if:
>>         required:
>>           - mux-reg-masks-state
>>       then:
>>         properties:
>>           idle-states: false
>>
>> required:
>>     - compatible
>>     - '#mux-control-cells'
>>
>> I think it won't disturb the current bindings and keep backward
>> compatibility with existing implementation.
> 
> Wasn't that the case before? There's nothing really different here.
> 

No, the binding before was not considering "mux-reg-masks" as required
property which was breaking actual dt-binding. In this binding, one of
the properties from "mux-reg-masks" or "mux-reg-masks-state" is required
which keeps the binding as it is unless someone wants to use
"mux-reg-masks-state".

Regards,
Chintan.

> Rob