Re: [PATCH v2 2/6] dt-bindings: pwm: amlogic: add new compatible for meson8 pwm type

[Jerome Brunet]

On Mon 20 Nov 2023 at 09:27, Neil Armstrong <neil.armstrong@xxxxxxxxxx> wrote:

> Hi Rob,
>
> On 19/11/2023 17:05, Rob Herring wrote:
>> On Fri, 17 Nov 2023 13:59:12 +0100, Jerome Brunet wrote:
>>> Add a new compatible for the pwm found in the meson8 to sm1 Amlogic SoCs.
>>>
>>> The previous clock bindings for these SoCs described the driver and not the
>>> HW itself. The clock provided was used to set the parent of the input clock
>>> mux among the possible parents hard-coded in the driver.
>>>
>>> The new bindings allows to describe the actual clock inputs of the PWM in
>>> DT, like most bindings do, instead of relying of hard-coded data.
>>>
>>> The new bindings make the old one deprecated.
>>>
>>> There is enough experience on this HW to know that the PWM is exactly the
>>> same all the supported SoCs. There is no need for a per-SoC compatible.
>>>
>>> Signed-off-by: Jerome Brunet <jbrunet@xxxxxxxxxxxx>
>>> ---
>>>   .../devicetree/bindings/pwm/pwm-amlogic.yaml  | 36 +++++++++++++++++--
>>>   1 file changed, 34 insertions(+), 2 deletions(-)
>>>
>> Reviewed-by: Rob Herring <robh@xxxxxxxxxx>
>> 
>
> I'm puzzled, isn't it recommended to have a per-soc compatible now ?

I have specifically addressed this matter in the description,
haven't I ? What good would it do in this case ?

Plus the definition of a SoC is very vague. One could argue that
the content of the list bellow are vaguely defined families. Should we
add meson8b, gxl, gxm, sm1 ? ... or even the actual SoC reference ?
This list gets huge for no reason.

We know all existing PWM of this type are the same. We have been using
them for years. It is not a new support we know nothing about.

>
> I thought something like:
> - items:
>     - enum:
>         - amlogic,gxbb-pwm
>         - amlogic,axg-pwm
>         - amlogic,g12a-pwm
>     - const: amlogic,pwm-v1

I'm not sure I understand what you are suggesting here.
Adding a "amlogic,pwm-v1" for the obsolete compatible ? No amlogic DT
has that and I'm working to remove this type, so I don't get the point.

>
> should be preferred instead of a single amlogic,meson8-pwm-v2 ?

This is named after the first SoC supporting the type.

Naming it amlogic,pwm-v2 would feel weird with the s4 coming after.
Plus the doc specifically advise against this type of names.

>
> Neil