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Date:   Tue, 25 Aug 2020 08:55:34 +0200
From:   "krzk@kernel.org" <krzk@kernel.org>
To:     "Vaittinen, Matti" <Matti.Vaittinen@fi.rohmeurope.com>
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Subject: Re: [PATCH 01/16] dt-bindings: mfd: rohm,bd71847-pmic: Correct clock
 properties requirements
Message-ID: <20200825065534.GB3458@kozik-lap>
References: <20200824190701.8447-1-krzk@kernel.org>
 <b75867fd1c662a83d933ae8f0c4373ba017eb808.camel@fi.rohmeurope.com>
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On Tue, Aug 25, 2020 at 06:23:36AM +0000, Vaittinen, Matti wrote:
> 
> Hello Krzysztof,
> 
> On Mon, 2020-08-24 at 21:06 +0200, Krzysztof Kozlowski wrote:
> > The input clock and number of clock provider cells are not required
> > for
> > the PMIC to operate.  They are needed only for the optional bd718x7
> > clock driver.
> 
> I have always found the DT bindings hard to do. I quite often end up
> having a different view with Rob so I probably could just shut-up and
> watch how this evolves :)
> 
> But as keeping my mouth is so difficult...
> 
> ...All of the drivers are optional. The PMIC can power-on without any
> drivers. Drivers are mostly used just for disabling the voltage from
> graphics accelerator block when it is not needed (optional). Or some
> DVS (optional). But yes, maybe the clk driver is "more optional" than
> the rest. XD So, I am not against this.

Each regulator node is optional, it can be skipped. And device will
work and regulator driver will bind. The difference here is that without
clocks the clock driver won't even bind... but if we keep clocks as
required, then multiple DTSes do not pass the bindings check.

I don't have strong feelings about dropping requirement for clocks, just
this looks easier to implement and logical to me (this is a PMIC so
clock is a secondary feature).

> 
> > Add also clock-output-names as driver takes use of it.
> > 
> > This fixes dtbs_check warnings like:
> > 
> >     arch/arm64/boot/dts/freescale/imx8mn-ddr4-evk.dt.yaml: pmic@4b:
> > 'clocks' is a required property
> >     arch/arm64/boot/dts/freescale/imx8mn-ddr4-evk.dt.yaml: pmic@4b:
> > '#clock-cells' is a required property
> > 
> > Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>
> > ---
> >  .../devicetree/bindings/mfd/rohm,bd71847-pmic.yaml       | 9
> > +++++++--
> >  1 file changed, 7 insertions(+), 2 deletions(-)
> > 
> > diff --git a/Documentation/devicetree/bindings/mfd/rohm,bd71847-
> > pmic.yaml b/Documentation/devicetree/bindings/mfd/rohm,bd71847-
> > pmic.yaml
> > index 77bcca2d414f..5d531051a153 100644
> > --- a/Documentation/devicetree/bindings/mfd/rohm,bd71847-pmic.yaml
> > +++ b/Documentation/devicetree/bindings/mfd/rohm,bd71847-pmic.yaml
> > @@ -38,6 +38,9 @@ properties:
> >    "#clock-cells":
> >      const: 0
> >  
> > +  clock-output-names:
> > +    maxItems: 1
> 
> I had this in original binding (text) document patch series. For some
> reason it was later dropped. Unfortunately I didn't easily find a
> reason as to why. Adding it back now is absolutely fine for me though.
> 
> > +
> >  # The BD71847 abd BD71850 support two different HW states as reset
> > target
> >  # states. States are called as SNVS and READY. At READY state all
> > the PMIC
> >  # power outputs go down and OTP is reload. At the SNVS state all
> > other logic
> > @@ -116,12 +119,14 @@ required:
> >    - compatible
> >    - reg
> >    - interrupts
> > -  - clocks
> > -  - "#clock-cells"
> >    - regulators
> >  
> >  additionalProperties: false
> >  
> > +dependencies:
> > +  '#clock-cells': [clocks]
> > +  clocks: ['#clock-cells']
> 
> This is new to me. Please educate me - does this simply mean that if
> '#clock-cells' is given, then also the 'clocks' must be given - and the
> other way around?

Yes, because the clocks do not have sense without clock-cells and vice versa.

> 
> If so, then:
> Acked-By: Matti Vaittinen <matti.vaittinen@fi.rohmeurope.com>
> 

Thanks.

Best regards,
Krzysztof