linux-kernel - Re: [PATCH v6 2/8] dt-bindings: iio: dac: adi-axi-dac: add ad3552r axi variant

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Message-ID: <35d247418b8bd43695644f395901b117a1014109.camel@gmail.com>
Date: Tue, 15 Oct 2024 16:51:04 +0200
From: Nuno Sá <noname.nuno@...il.com>
To: David Lechner <dlechner@...libre.com>, Angelo Dureghello
	 <adureghello@...libre.com>
Cc: Nuno Sá <nuno.sa@...log.com>, Lars-Peter Clausen
	 <lars@...afoo.de>, Michael Hennerich <Michael.Hennerich@...log.com>, 
 Jonathan Cameron
	 <jic23@...nel.org>, Rob Herring <robh@...nel.org>, Krzysztof Kozlowski
	 <krzk+dt@...nel.org>, Conor Dooley <conor+dt@...nel.org>, Olivier Moysan
	 <olivier.moysan@...s.st.com>, linux-iio@...r.kernel.org, 
	devicetree@...r.kernel.org, linux-kernel@...r.kernel.org, Mark Brown
	 <broonie@...nel.org>
Subject: Re: [PATCH v6 2/8] dt-bindings: iio: dac: adi-axi-dac: add ad3552r
 axi variant

On Tue, 2024-10-15 at 09:40 -0500, David Lechner wrote:
> On 10/15/24 2:44 AM, Angelo Dureghello wrote:
> > On 14.10.2024 16:13, David Lechner wrote:
> > > On 10/14/24 5:08 AM, Angelo Dureghello wrote:
> > > > From: Angelo Dureghello <adureghello@...libre.com>
> > > > 
> > > > Add a new compatible and related bindigns for the fpga-based
> > > > "ad3552r" AXI IP core, a variant of the generic AXI DAC IP.
> > > > 
> > > > The AXI "ad3552r" IP is a very similar HDL (fpga) variant of the
> > > > generic AXI "DAC" IP, intended to control ad3552r and similar chips,
> > > > mainly to reach high speed transfer rates using a QSPI DDR
> > > > (dobule-data-rate) interface.
> > > > 
> > > > The ad3552r device is defined as a child of the AXI DAC, that in
> > > > this case is acting as an SPI controller.
> > > > 
> > > > Note, #io-backend is present because it is possible (in theory anyway)
> > > > to use a separate controller for the control path than that used
> > > > for the datapath.
> > > > 
> > > > Signed-off-by: Angelo Dureghello <adureghello@...libre.com>
> > > > ---
> > > >  .../devicetree/bindings/iio/dac/adi,axi-dac.yaml   | 56
> > > > ++++++++++++++++++++--
> > > >  1 file changed, 53 insertions(+), 3 deletions(-)
> > > > 
> > > > diff --git a/Documentation/devicetree/bindings/iio/dac/adi,axi-dac.yaml
> > > > b/Documentation/devicetree/bindings/iio/dac/adi,axi-dac.yaml
> > > > index a55e9bfc66d7..2b7e16717219 100644
> > > > --- a/Documentation/devicetree/bindings/iio/dac/adi,axi-dac.yaml
> > > > +++ b/Documentation/devicetree/bindings/iio/dac/adi,axi-dac.yaml
> > > > @@ -19,11 +19,13 @@ description: |
> > > >    memory via DMA into the DAC.
> > > >  
> > > >    https://wiki.analog.com/resources/fpga/docs/axi_dac_ip
> > > > +  https://analogdevicesinc.github.io/hdl/library/axi_ad3552r/index.html
> > > >  
> > > >  properties:
> > > >    compatible:
> > > >      enum:
> > > >        - adi,axi-dac-9.1.b
> > > > +      - adi,axi-ad3552r
> > > >  
> > > >    reg:
> > > >      maxItems: 1
> > > > @@ -36,7 +38,14 @@ properties:
> > > >        - const: tx
> > > >  
> > > >    clocks:
> > > > -    maxItems: 1
> > > > +    minItems: 1
> > > > +    maxItems: 2
> > > > +
> > > > +  clock-names:
> > > > +    minItems: 1
> > > > +    items:
> > > > +      - const: s_axi_aclk
> > > > +      - const: dac_clk
> > > >  
> > > >    '#io-backend-cells':
> > > >      const: 0
> > > > @@ -47,7 +56,16 @@ required:
> > > >    - reg
> > > >    - clocks
> > > >  
> > > > -additionalProperties: false
> > > > +allOf:
> > > > +  - if:
> > > > +      properties:
> > > > +        compatible:
> > > > +          contains:
> > > > +            const: adi,axi-ad3552r
> > > > +    then:
> > > > +      $ref: /schemas/spi/spi-controller.yaml#
> > >   +      properties:
> > >   +        clocks:
> > >   +          minItems: 2
> > >   +        clock-names:
> > >   +          minItems: 2
> > >   +      required:
> > >   +        clock-names
> > >   +    else:
> > >   +      properties:
> > >   +        clocks:
> > >   +          maxItems: 1
> > >   +        clock-names:
> > >   +          maxItems: 1
> > > 
> > > We could make the checking of clocks more strict to show
> > > the intent:
> > > 
> > > adi,axi-dac-9.1.b only has 1 clock and clock-names is optional.
> > > 
> > > adi,axi-ad3552r always has 2 clocks and clock-names is required.
> > > 
> > is this really necessary ? At v.6 would not fix things
> > not reallyh necessary.
> >  
> It is just a suggestion from me. I will leave it to the maintainers
> to say if it is necessary or not. (If they don't say anything, then
> we'll take it to mean it isn't necessary.)
> 

Not a DT maintainer but IMHO, having these kind of checks in the bindings is very
useful.

- Nuno Sá