linux-kernel - RE: [PATCH v2 1/3] dt-bindings: thermal: samsung: Add tmu-name and sensor-index-ranges properties

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Message-ID: <022001dc1e41$46f7ba60$d4e72f20$@samsung.com>
Date: Fri, 5 Sep 2025 17:44:22 +0900
From: 손신 <shin.son@...sung.com>
To: "'Krzysztof Kozlowski'" <krzk@...nel.org>
Cc: "'Bartlomiej Zolnierkiewicz'" <bzolnier@...il.com>, "'Rafael J .
 Wysocki'" <rafael@...nel.org>, "'Daniel Lezcano'"
	<daniel.lezcano@...aro.org>, "'Zhang Rui'" <rui.zhang@...el.com>, "'Lukasz
 Luba'" <lukasz.luba@....com>, "'Rob Herring'" <robh@...nel.org>, "'Conor
 Dooley'" <conor+dt@...nel.org>, "'Alim Akhtar'" <alim.akhtar@...sung.com>,
	<linux-pm@...r.kernel.org>, <linux-samsung-soc@...r.kernel.org>,
	<devicetree@...r.kernel.org>, <linux-arm-kernel@...ts.infradead.org>,
	<linux-kernel@...r.kernel.org>
Subject: RE: [PATCH v2 1/3] dt-bindings: thermal: samsung: Add tmu-name and
 sensor-index-ranges properties

Hello Krzysztof Kozlowski,

> -----Original Message-----
> From: Krzysztof Kozlowski [mailto:krzk@...nel.org]
> Sent: Thursday, September 4, 2025 5:00 PM
> To: Shin Son <shin.son@...sung.com>
> Cc: Bartlomiej Zolnierkiewicz <bzolnier@...il.com>; Rafael J . Wysocki
> <rafael@...nel.org>; Daniel Lezcano <daniel.lezcano@...aro.org>; Zhang Rui
> <rui.zhang@...el.com>; Lukasz Luba <lukasz.luba@....com>; Rob Herring
> <robh@...nel.org>; Conor Dooley <conor+dt@...nel.org>; Alim Akhtar
> <alim.akhtar@...sung.com>; linux-pm@...r.kernel.org; linux-samsung-
> soc@...r.kernel.org; devicetree@...r.kernel.org; linux-arm-
> kernel@...ts.infradead.org; linux-kernel@...r.kernel.org
> Subject: Re: [PATCH v2 1/3] dt-bindings: thermal: samsung: Add tmu-name
> and sensor-index-ranges properties
> 
> On Wed, Sep 03, 2025 at 04:36:32PM +0900, Shin Son wrote:
> > The exynosautov920 TMU requires per-sensor interrupt enablement for
> > its critical trip points.
> > Add a DT property to the Samsung thermal bindings to support this
> > requirement:
> 
> That's pretty redundant sentence.

I'll remove this sentence.

> >
> > - **samsung,hw-sensor-indices**: Defines the sensors currently
> >                                  mapped to the TMU hardware.
> > 				 Indices not listed are absent or fused off
> 
> Don't write here any code, but concise prose dxescribing hardware.
> 
> If sensors are fused out, you certainly can read their status from efuse,
> no?

"fused out" was a wrong expression — sensors are not indicated in any register. Sorry for the confusion.
The hardware does not provide a bitmask of present sensors.
Therefore, the DT must explicitly list which indices belong to this TMU instance.

Additionally, I'll rephrase this sentence to clearly describe the TMU hardware only.

> 
> This is really vague description of hardware. I don't understand why you
> are changing sensor-cells, why older variants of tmu gets now cells=1
> (missing constraints?).
> 
> Why older variants also get that property for sensors? It does not make
> sense there, because they have one-to-one mapping between TMU and sensor.

Older variants should be fixed to 0,
but my patch mistakenly opened it with an enum so that 1 was also allowed there, I'll fix this.
I'll also restrict the sensor indices property to v920 only.

> 
> >
> > Additionally, add myself to the bindings' maintainers list, as I plan
> > to actively work on the exynosautov920 TMU support and handle further
> > updates in this area.
> >
> > Signed-off-by: Shin Son <shin.son@...sung.com>
> > ---
> >  .../bindings/thermal/samsung,exynos-thermal.yaml | 16
> > +++++++++++++++-
> >  1 file changed, 15 insertions(+), 1 deletion(-)
> >
> > diff --git
> > a/Documentation/devicetree/bindings/thermal/samsung,exynos-thermal.yam
> > l
> > b/Documentation/devicetree/bindings/thermal/samsung,exynos-thermal.yam
> > l index 29a08b0729ee..abd89902d33a 100644
> > ---
> > a/Documentation/devicetree/bindings/thermal/samsung,exynos-thermal.yam
> > l
> > +++ b/Documentation/devicetree/bindings/thermal/samsung,exynos-thermal
> > +++ .yaml
> > @@ -8,6 +8,7 @@ title: Samsung Exynos SoC Thermal Management Unit
> > (TMU)
> >
> >  maintainers:
> >    - Krzysztof Kozlowski <krzk@...nel.org>
> > +  - Shin Son <shin.son@...sung.com>
> >
> >  description: |
> >    For multi-instance tmu each instance should have an alias correctly
> > numbered @@ -27,6 +28,7 @@ properties:
> >        - samsung,exynos5420-tmu-ext-triminfo
> >        - samsung,exynos5433-tmu
> >        - samsung,exynos7-tmu
> > +      - samsung,exynosautov920-tmu
> >
> >    clocks:
> >      minItems: 1
> > @@ -62,11 +64,22 @@ properties:
> >      minItems: 1
> >
> >    '#thermal-sensor-cells':
> > -    const: 0
> > +    enum:
> > +      - 0
> > +      - 1
> >
> >    vtmu-supply:
> >      description: The regulator node supplying voltage to TMU.
> >
> > +  samsung,hw-sensor-indices:
> > +    description: |
> 
> Drop |

I'll drop this.

> 
> > +      List of hardware sensor indices that are physically present and
> usable
> > +      in this TMU instance. Indices not listed are either unmapped or
> unused.
> > +    $ref: /schemas/types.yaml#/definitions/uint32-array
> > +    minItems: 1
> > +    maxItems: 16
> > +    uniqueItems: true
> 
> Best regards,
> Krzysztof

Thanks.

Best regards,
Shin Son