Re: [PATCH v4 1/4] dt-bindings: mfd: Document RZ/G2L MTU3a bindings

[Lee Jones <lee@kernel.org>]

On Tue, 11 Oct 2022, Biju Das wrote:

> 
> Hi Krzysztof Kozlowski,
> 
> > Subject: Re: [PATCH v4 1/4] dt-bindings: mfd: Document RZ/G2L MTU3a
> > bindings
> > 
> > On 10/10/2022 10:52, Biju Das wrote:
> > > The RZ/G2L multi-function timer pulse unit 3 (MTU3a) is embedded in
> > > the Renesas RZ/G2L family SoC's. It consists of eight 16-bit timer
> > > channels and one 32-bit timer channel. It supports the following
> > > functions
> > >  - Counter
> > >  - Timer
> > >  - PWM
> > >
> > > Signed-off-by: Biju Das <biju.das.jz@bp.renesas.com>
> > > ---
> > > v3->v4:
> > >  * Dropped counter and pwm compatibeles as they don't have any
> > resources.
> > >  * Made rz-mtu3 as pwm provider.
> > >  * Updated the example and description.
> > > v2->v3:
> > >  * Dropped counter bindings and integrated with mfd as it has only
> > one property.
> > >  * Removed "#address-cells" and "#size-cells" as it do not have
> > children with
> > >    unit addresses.
> > >  * Removed quotes from counter and pwm.
> > >  * Provided full path for pwm bindings.
> > >  * Updated the example.
> > > v1->v2:
> > >  * Modelled counter and pwm as a single device that handles
> > >    multiple channels.
> > >  * Moved counter and pwm bindings to respective subsystems
> > >  * Dropped 'bindings' from MFD binding title.
> > >  * Updated the example
> > >  * Changed the compatible names.
> > > ---
> > >  .../bindings/mfd/renesas,rz-mtu3.yaml         | 305
> > ++++++++++++++++++
> > >  1 file changed, 305 insertions(+)
> > >  create mode 100644
> > > Documentation/devicetree/bindings/mfd/renesas,rz-mtu3.yaml
> > 
> > This should not be in MFD. Just because some device has few features,
> > does not mean it should go to MFD... Choose either timer or pwm.
> 
> MFD is for multifunction device. This IP supports multiple functions
> like timer, pwm, clock source/events. That is the reason I have added 
> here. MFD is core which provides register access for client devices.
> 
> For me moving it to pwm or counter is not a big problem.
> Why do you think it cannot be MFD?

Sorry for jumping in late here.  I see this has been resolved.

The TL;DR is: if you're not using the MFD Core (and including
mfd/core.h), it's not an MFD.  You *could* split this up into its
component parts, place them into their own subsystems and use an MFD
core driver to register them all, but as Thierry says, this is not a
hard requirement either.

-- 
Lee Jones [李琼斯]