Re: [PATCH v2 3/7] dt-bindings: thermal: r9a09g047-tsu: Document the TSU unit

[Conor Dooley <conor@kernel.org>]

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On Fri, Mar 07, 2025 at 03:14:05PM +0000, John Madieu wrote:
> Hi Conor,
> 
> Thanks for your review!
> 
> > -----Original Message-----
> > From: Conor Dooley <conor@kernel.org>
> > Sent: Friday, February 28, 2025 8:03 PM
> > To: John Madieu <john.madieu.xa@bp.renesas.com>
> > Subject: Re: [PATCH v2 3/7] dt-bindings: thermal: r9a09g047-tsu: Document
> > the TSU unit
> > 
> > On Thu, Feb 27, 2025 at 01:24:39PM +0100, John Madieu wrote:
> > > The Renesas RZ/G3E SoC includes a Thermal Sensor Unit (TSU) block
> > > designed to measure the junction temperature. The device provides
> > > real-time temperature measurements for thermal management, utilizing a
> > > single dedicated channel (channel 1) for temperature sensing.
> > >
> > > Signed-off-by: John Madieu <john.madieu.xa@bp.renesas.com>
> > > ---
> > > v1 -> v2:
> > >  * Fix reg property specifier to get rid of yamlint warnings
> > >  * Fix IRQ name to reflect TSU expectations
> > >
> > >  .../thermal/renesas,r9a09g047-tsu.yaml        | 123 ++++++++++++++++++
> > >  1 file changed, 123 insertions(+)
> > >  create mode 100644
> > > Documentation/devicetree/bindings/thermal/renesas,r9a09g047-tsu.yaml
> > >
> > > diff --git
> > > a/Documentation/devicetree/bindings/thermal/renesas,r9a09g047-tsu.yaml
> > > b/Documentation/devicetree/bindings/thermal/renesas,r9a09g047-tsu.yaml
> > > new file mode 100644
> > > index 000000000000..e786561ddbe3
> > > --- /dev/null
> > > +++ b/Documentation/devicetree/bindings/thermal/renesas,r9a09g047-tsu.
> > > +++ yaml
> > > @@ -0,0 +1,123 @@
> > > +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause) %YAML 1.2
> > > +---
> > > +$id:
> > > +http://devicetree.org/schemas/thermal/renesas,r9a09g047-tsu.yaml#
> > > +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > > +
> > > +title: Renesas RZ/G3E Temperature Sensor Unit (TSU)
> > > +
> > > +maintainers:
> > > +  - John Madieu <john.madieu.xa@bp.renesas.com>
> > > +
> > > +description:
> > > +  The Temperature Sensor Unit (TSU) is an integrated thermal sensor
> > > +that
> > > +  monitors the chip temperature on the Renesas RZ/G3E SoC. The TSU
> > > +provides
> > > +  real-time temperature measurements for thermal management.
> > > +
> > > +properties:
> > > +  compatible:
> > > +    const: renesas,r9a09g047-tsu
> > > +
> > > +  reg:
> > > +    maxItems: 1
> > > +
> > > +  clocks:
> > > +    maxItems: 1
> > > +
> > > +  resets:
> > > +    maxItems: 1
> > > +
> > > +  power-domains:
> > > +    maxItems: 1
> > > +
> > > +  interrupts:
> > > +    description: |
> > > +      Interrupt specifiers for the TSU:
> > > +      - S12TSUADI1: Conversion complete interrupt signal (pulse)
> > > +      - S12TSUADCMPI1: Comparison result interrupt signal (level)
> > > +
> > > +  interrupt-names:
> > > +    items:
> > > +      - const: adi
> > > +      - const: adcmpi
> > > +
> > > +  "#thermal-sensor-cells":
> > > +    const: 0
> > > +
> > > +  renesas,tsu-calibration-sys:
> > > +    $ref: /schemas/types.yaml#/definitions/phandle
> > > +    description: |
> > > +      Phandle to the system controller (sys) that contains the TSU
> > > +      calibration values used for temperature calculations.
> > > +
> > > +  renesas,tsu-operating-mode:
> > > +    $ref: /schemas/types.yaml#/definitions/uint32
> > > +    enum: [0, 1]
> > > +    description: |
> > > +      TSU operating mode:
> > > +      0: Mode 0 - Conversion started by software
> > > +      1: Mode 1 - Conversion started by ELC trigger
> > 
> > Can you make this "software" and "elc" or something please, unless people
> > will genuinely find "0" and 1" to be more informative.
> > And why doesn't the property have a default?
> 
> Sorry for miss-specifying.
> ELC is an external event trigger. May be should I specify it like that ?

If "elc trigger" is meaningful to people using hte device (IOW, it
matches datasheet wording) then that's fine I think.

> To make sure I got your point, do you mean specifying a default value in
> bindings ?

The property doesn't actually need to be required, it could easily have
a default (say software) and only be set in the case of using the elc
trigger - which brings you to Rob's comment that it can just be a
boolean, setting the property if elc and leaving it out of software.

Rob's other comment was

| Who/what decides the mode? If a user is going to want to change this, 
| then it should be a runtime control, not a DT property.

which I think needs an answer ;)

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