Re: [PATCH v7 4/6] dt-bindings: mailbox: imx-mu: add i.MX6SX and i.MX7S SoCs.

[Vladimir Zapolskiy <vladimir_zapolskiy-nmGgyN9QBj3QT0dZR+AlfA@public.gmane.org>]

On 07/26/2018 03:10 PM, Jassi Brar wrote:
> On Thu, Jul 26, 2018 at 5:25 PM, Vladimir Zapolskiy
> <vladimir_zapolskiy-nmGgyN9QBj3QT0dZR+AlfA@public.gmane.org> wrote:
>> On 07/26/2018 02:52 PM, Jassi Brar wrote:
>>> On Thu, Jul 26, 2018 at 5:14 PM, Vladimir Zapolskiy
>>> <vladimir_zapolskiy-nmGgyN9QBj3QT0dZR+AlfA@public.gmane.org> wrote:
> 
>>>>
>>> Please note the submitted driver absolutely don't care which of the
>>> five SoCs it is.
>>
>> True.
>>
> 
>>> In other words, all these SoCs have the same controller.
>>
>> False :)
>>

To be more precice, the statement itself may be true or false, but
the implication ("In other words, ...") is definitely false.

> OK, so the controllers are not identical, but same enough to have a
> common driver?

Right, the controllers are compatible, but likely they are non-identical.

> Is the driver not tested enough or are you planning to add more features?
> 

Test results can not serve as a formal eternal proof, but they are good as
a hint. Also I'm not aware of any pending features to be added to the driver.

>>> So its about have just one compatible right now, and add more if some
>>> new SoC comes with a variation of the controller.
>>>
>>
>> True. The driver will be changed in this case, unfortunately the bindings
>> are not so volatile.
>>
> The volatility of the bindings will be same when you add a new SoC
> compatible ;)  And you must add to bindings+driver, or the same h/w
> and same driver won't work for your new platform.
> 

The (non-)volatilitily of the bindings is important only in retrospective
view.

Adding a new compatible to the documentation and unrelated board DTBs is
irrelevant, and it is quite predictable that it will happen, when a new
SoC with the same "compatible" IP is released.

--
Best wishes,
Vladimir