linux-kernel - Re: [PATCH v1 3/3] dt-bindings: thermal: sun8i: Add binding for D1/T113s THS controller

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Date:   Sat, 10 Jun 2023 23:13:52 +0100
From:   Conor Dooley <conor@...nel.org>
To:     Maxim Kiselev <bigunclemax@...il.com>
Cc:     linux-kernel@...r.kernel.org,
        Vasily Khoruzhick <anarsoul@...il.com>,
        Yangtao Li <tiny.windzz@...il.com>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Daniel Lezcano <daniel.lezcano@...aro.org>,
        Amit Kucheria <amitk@...nel.org>,
        Zhang Rui <rui.zhang@...el.com>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Conor Dooley <conor+dt@...nel.org>,
        Chen-Yu Tsai <wens@...e.org>,
        Jernej Skrabec <jernej.skrabec@...il.com>,
        Samuel Holland <samuel@...lland.org>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        Palmer Dabbelt <palmer@...belt.com>,
        Albert Ou <aou@...s.berkeley.edu>,
        Cristian Ciocaltea <cristian.ciocaltea@...labora.com>,
        linux-pm@...r.kernel.org, devicetree@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-sunxi@...ts.linux.dev,
        linux-riscv@...ts.infradead.org
Subject: Re: [PATCH v1 3/3] dt-bindings: thermal: sun8i: Add binding for
 D1/T113s THS controller

On Sat, Jun 10, 2023 at 11:31:03PM +0300, Maxim Kiselev wrote:
> сб, 10 июн. 2023 г. в 21:01, Conor Dooley <conor@...nel.org>:
> 
> ...
> 
> > > > > +  - |
> > > > > +    thermal-sensor@...9400 {
> > > > > +          compatible = "allwinner,sun20i-d1-ths";
> > > > > +          reg = <0x02009400 0x400>;
> > > > > +          interrupts = <0 90 0>;
> > > > > +          clocks = <&ccu 0>;
> > > > > +          clock-names = "bus";
> > > > > +          resets = <&ccu 2>;
> > > > > +          nvmem-cells = <&ths_calibration>;
> > > > > +          nvmem-cell-names = "calibration";
> > > > > +          #thermal-sensor-cells = <0>;
> > > > >
> > > > >> Is this calibration required, or optional, for the d1?
> > > >
> > > > Calibration data for the D1 is optional as for the H6.
> > > > (But without it, the sensor data will be inaccurate).
> > >
> > > Okay. Modulo the signoff:
> > > Reviewed-by: Conor Dooley <conor.dooley@...rochip.com>
> >
> > Wait, that's not what I meant to say... Clearly turned my brain off for
> > a moment. If it is not going to function correctly without the
> > calibration data, why not make the calibration data required for the
> > d1's ths?
> 
> I don't really know why, but the calibration data is optional for
> other controllers.
> So I just did it the same way.
> Here is explanation comment about it from the driver:
>         /*
>          * Even if the external calibration data stored in sid is
>          * not accessible, the THS hardware can still work, although
>          * the data won't be so accurate.
>          *
>          * The default value of calibration register is 0x800 for
>          * every sensor, and the calibration value is usually 0x7xx
>          * or 0x8xx, so they won't be away from the default value
>          * for a lot.
>          *
>          * So here we do not return error if the calibration data is
>          * not available, except the probe needs deferring.
>          */

Wait, so if there is no calibration data then this thing will just defer
probing, ad infinitum? Looks like everything other than the a33 has the
cells in the dts, and the software seems to expect the cells.
What am I missing?



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