linux-kernel - Re: [PATCH v6 7/7] arm64: dts: sdm845: Add tsens nodes

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Date:   Wed, 11 Jul 2018 15:00:55 -0700
From:   Doug Anderson <dianders@...omium.org>
To:     Matthias Kaehlcke <mka@...omium.org>
Cc:     Amit Kucheria <amit.kucheria@...aro.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Rajendra Nayak <rnayak@...eaurora.org>,
        linux-arm-msm <linux-arm-msm@...r.kernel.org>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Eduardo Valentin <edubezval@...il.com>,
        smohanad@...eaurora.org,
        Vivek Gautam <vivek.gautam@...eaurora.org>,
        Andy Gross <andy.gross@...aro.org>,
        David Brown <david.brown@...aro.org>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will.deacon@....com>,
        "open list:ARM/QUALCOMM SUPPORT" <linux-soc@...r.kernel.org>,
        devicetree@...r.kernel.org,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH v6 7/7] arm64: dts: sdm845: Add tsens nodes

Hi Matthias,

On Wed, Jul 11, 2018 at 2:51 PM, Matthias Kaehlcke <mka@...omium.org> wrote:
> On Wed, Jul 11, 2018 at 11:44:13AM -0700, Doug Anderson wrote:
>> Hi,
>>
>> On Mon, Jul 9, 2018 at 4:43 AM, Amit Kucheria <amit.kucheria@...aro.org> wrote:
>> > SDM845 has two tsens blocks, one with 13 sensors and the other with 8
>> > sensors. It uses version 2 of the TSENS IP, so use the fallback property to
>> > allow more common code.
>> >
>> > Signed-off-by: Amit Kucheria <amit.kucheria@...aro.org>
>> > ---
>> >  arch/arm64/boot/dts/qcom/sdm845.dtsi | 16 ++++++++++++++++
>> >  1 file changed, 16 insertions(+)
>> >
>> > diff --git a/arch/arm64/boot/dts/qcom/sdm845.dtsi b/arch/arm64/boot/dts/qcom/sdm845.dtsi
>> > index cdaabeb..ba2899c 100644
>> > --- a/arch/arm64/boot/dts/qcom/sdm845.dtsi
>> > +++ b/arch/arm64/boot/dts/qcom/sdm845.dtsi
>> > @@ -221,6 +221,22 @@
>> >                         #interrupt-cells = <2>;
>> >                 };
>> >
>> > +               tsens0: tsens@...3000 {
>>
>> As per my comments in the bindings, nit that this should probably be
>> "thermal-sensor" not "tsens", AKA:
>>
>> tsens0: thermal-sensor@...3000 {
>>
>> > +                       compatible = "qcom,sdm845-tsens", "qcom,tsens-v2";
>> > +                       reg = <0xc263000 0x1ff>, /* TM */
>> > +                             <0xc222000 0x1ff>; /* SROT */
>> > +                       #qcom,sensors = <13>;
>>
>> As per my comment in the bindings and the code, I'm confused about the
>> whole "#qcom,sensors" bit.  It's not documented and doesn't seem
>> hooked up in the code either.
>>
>> ...but if people have tested this, perhaps I'm confused.  How can
>> things work if num_sensors is 0???
>
> The mystery is resolved by:
>
> commit 6d7c70d1cd6526dc79e3d3b3faae1c40c1681168
> Author: Bjorn Andersson <bjorn.andersson@...aro.org>
> Date:   Mon May 7 16:53:39 2018 -0700
>
>     thermal: qcom: tsens: Allow number of sensors to come from DT
>
>     For platforms that has multiple copies of the TSENS hardware block it's
>     necessary to be able to specify the number of sensors per block in DeviceTree.
>
>     Signed-off-by: Bjorn Andersson <bjorn.andersson@...aro.org>
>     Reviewed-by: Amit Kucheria <amit.kucheria@...aro.org>
>     Reviewed-by: Rob Herring <robh@...nel.org>
>     Signed-off-by: Eduardo Valentin <edubezval@...il.com>
>
>
> I bumped into this during testing ;-)

Ah, now it makes sense to me!  Serves me right for assuming it would
be in the same series and not checking if it was something that had
already landed.  Thanks.  Please ignore the parts of my comments
related to the "#qcom,sensors" property.  I guess Rob must have
thought that the "#" in the name was fine and he's the one in charge
not me.

-Doug