Hi Lee,
> Subject: Re: [PATCH RFC 3/7] dt-bindings: mfd: rz-mtu3: Document
> RZ/G2L MTU3 PWM
>
> On Mon, 03 Oct 2022, Biju Das wrote:
>
> > Hi Lee,
> >
> > > Subject: Re: [PATCH RFC 3/7] dt-bindings: mfd: rz-mtu3: Document
> > > RZ/G2L MTU3 PWM
> > >
> > > On Sat, 01 Oct 2022, Biju Das wrote:
> > >
> > > > Hi Lee Jones,
> > > >
> > > > > Subject: Re: [PATCH RFC 3/7] dt-bindings: mfd: rz-mtu3:
> Document
> > > > > RZ/G2L MTU3 PWM
> > > > >
> > > > > On Thu, 29 Sep 2022, Biju Das wrote:
> > > > >
> > > > > > Hi Lee Jones,
> > > > > >
> > > > > > Thanks for the feedback.
> > > > > >
> > > > > > > Subject: Re: [PATCH RFC 3/7] dt-bindings: mfd: rz-mtu3:
> > > Document
> > > > > > > RZ/G2L MTU3 PWM
> > > > > > >
> > > > > > > On Thu, 29 Sep 2022, Biju Das wrote:
> > > > > > >
> > > > > > > > Document RZ/G2L MTU3 PWM support. It supports following
> > > > > > > > pwm
> > > > > modes.
> > > > > > > > 1) PWM mode 1
> > > > > > > > 2) PWM mode 2
> > > > > > > > 3) Reset-synchronized PWM mode
> > > > > > > > 4) Complementary PWM mode 1 (transfer at crest)
> > > > > > > > 5) Complementary PWM mode 2 (transfer at trough)
> > > > > > > > 6) Complementary PWM mode 3 (transfer at crest and
> > > > > > > > trough)
> > > > > > >
> > > > > > > Shouldn't all this go in the PWM driver binding?
> > > > > >
> > > > > > Looks like at top level MTU3 IP provides similar HW
> > > functionality
> > > > > like
> > > > > > below binding [1], where there is a core MFD driver and pwm,
> > > > > > counter and timer as child devices.
> > > > >
> > > > > Previous mistakes are not good references for what should
> happen
> > > in
> > > > > the present and the future. =;)
> > > >
> > > > Why do you think that reference is not a good one? I believe
> there
> > > > should be some reason for it.
> > >
> > > I didn't even look at it.
> > >
> > > What I "believe" is that documentation for each functionality
> > > belonging to a particular subsystem should live in subsystem's
> > > associated documentation directory and be reviewed/maintained by
> > > that subsystem's associated maintainer.
> >
> > If I am correct, MFD is subsystem for calling shared resources
> across
> > subsystems.
> >
> > Here shared resources are channels which is shared by timer, counter
> > and pwm
>
> Which API do the consumers use to obtain these shared resources?
They need to use MFD driver API to get shared resources.
>
> > They are child objects of MFD subsystems. That is the reason it is
> in MFDndings.
>
> If the properties belong to the child, they should be documented in
> the child's bindings. Shoving all functionality and by extension all
> documentation into the MFD driver and/or binding is incorrect
> behaviour.
Do you have an example, how will it look like, if the below binding to be part of
pwm and linked against the parent MFD driver?
+ "^pwm@([0-4]|[6-7])+$":
+ type: object
+
+ properties:
+ compatible:
+ const: renesas,rz-mtu3-pwm
+
+ reg:
+ description: Identify pwm channels.
+ items:
+ enum: [ 0, 1, 2, 3, 4, 6, 7 ]
+
+ "#pwm-cells":
+ const: 2
+
+ renesas,pwm-mode1:
+ type: boolean
+ description: Enable PWM mode 1.
+
+ renesas,pwm-mode2:
+ type: boolean
+ description: Enable PWM mode 2.
+
+ renesas,reset-synchronized-pwm-mode:
+ type: boolean
+ description: Enable Reset-synchronized PWM mode.
+
+ renesas,complementary-pwm-mode1:
+ type: boolean
+ description: Complementary PWM mode 1 (transfer at crest).
+
+ renesas,complementary-pwm-mode2:
+ type: boolean
+ description: Complementary PWM mode 2 (transfer at trough).
+
+ renesas,complementary-pwm-mode3:
+ type: boolean
+ description: Complementary PWM mode 3 (transfer at crest and trough).
+
+ required:
+ - compatible
+ - reg
+ - "#pwm-cells"
+
examples:
+ pwm@3 {
+ compatible = "renesas,rz-mtu3-pwm";
+ reg = <3>;
+ #pwm-cells = <2>;
+ renesas,pwm-mode1;
+ };
};
Cheers,
Biju
>
> Looking at it from another perspective, I cannot/should not review
> PWM, Reset, Counter or Timer bindings, since I do not have the level
> of subject area knowledge as the assigned maintainers do.
>
> Please place all sub-system specific bindings in their correct (leaf)
> bindings and link to them from this one (run this):
>
> git grep \$ref -- Documentation/devicetree/bindings/mfd/
>
> --
> Lee Jones [李琼斯]
