Re: [PATCH v3 2/5] dt-bindings: mfd: Add support for Airoha EN7581 GPIO System Controller

[Christian Marangi <ansuelsmth@gmail.com>]

On Tue, Sep 03, 2024 at 05:42:18PM +0100, Lee Jones wrote:
> On Tue, 03 Sep 2024, Christian Marangi wrote:
> 
> > On Tue, Sep 03, 2024 at 04:33:53PM +0100, Lee Jones wrote:
> > > On Sat, 31 Aug 2024, Lorenzo Bianconi wrote:
> > > 
> > > > From: Christian Marangi <ansuelsmth@gmail.com>
> > > > 
> > > > Add support for Airoha EN7581 GPIO System Controller which provide a
> > > > register map for controlling the GPIO, pinctrl and PWM of the SoC.
> > > > 
> > > > Schema define cells for both gpio/interrupt controller and PWM.
> > > > Moreover it provides a dedicated pinctrl node for pins and config
> > > > definitions.
> > > > 
> > > > Signed-off-by: Christian Marangi <ansuelsmth@gmail.com>
> > > > Co-developed-by: Lorenzo Bianconi <lorenzo@kernel.org>
> > > > Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
> > > > ---
> > > >  .../bindings/mfd/airoha,en7581-gpio-sysctl.yaml    | 433 +++++++++++++++++++++
> > > >  1 file changed, 433 insertions(+)
> > > > 
> > > > diff --git a/Documentation/devicetree/bindings/mfd/airoha,en7581-gpio-sysctl.yaml b/Documentation/devicetree/bindings/mfd/airoha,en7581-gpio-sysctl.yaml
> > > > new file mode 100644
> > > > index 000000000000..a9080c7f50f9
> > > > --- /dev/null
> > > > +++ b/Documentation/devicetree/bindings/mfd/airoha,en7581-gpio-sysctl.yaml
> > > > @@ -0,0 +1,433 @@
> > > > +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
> > > > +%YAML 1.2
> > > > +---
> > > > +$id: http://devicetree.org/schemas/mfd/airoha,en7581-gpio-sysctl.yaml#
> > > > +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > > > +
> > > > +title: Airoha EN7581 GPIO System Controller
> > > > +
> > > > +maintainers:
> > > > +  - Christian Marangi <ansuelsmth@gmail.com>
> > > > +  - Lorenzo Bianconi <lorenzo@kernel.org>
> > > > +
> > > > +description:
> > > > +  Airoha EN7581 SoC GPIO system controller which provided a register map
> > > > +  for controlling the GPIO, pins and PWM of the SoC.
> > > 
> > > This whole thing is just about pins.
> > > 
> > > The MFD portion of this submission doesn't do anything.
> > >
> > 
> > Hi Lee,
> > 
> > thanks for the review. I think you missed the other series as it was
> > requested to use MFD implementation due to shared register map.
> > 
> > > Please rework this to omit the MFD driver.
> > 
> > I'm a bit confused by this you mean in the schema? Putting PWM property
> > in a pinctrl schema looks wrong to me :(
> > 
> > > 
> > > After just a glance, it looks like simple-mfd _might_ work.
> > 
> > Simple-mfd works if register map are well defined and you can have
> > something like
> > - parent define the whole register
> > - child can user reg property to register offset and subsection of the
> >   parent register
> > 
> > Here it's all mixed and scrambled and also it was requested to have a
> > very simple node that include both pwm and pinctrl property (cause that
> > is how the HW register block is designed and schema must reflect HW)
> > 
> > Hope you can understand these reasons.
> 
> Thinking very quickly before I have to rush off.
> 
> Have you considered syscon?
>

Yes it was considered and proposed but it's not suitable for what it was
suggested from DT guy. A syscon implementation would require adding
child nodes with compatible (to probe driver that way) and that got
rejected.

The main reason is that it's wrong to create .yaml that describe how
the driver structure works (mfd + child nodes with compatible) instead
of describing how the actual HW works (single register map that expose
both GPIO/PINCTRL and PWM)

-- 
	Ansuel