linux-kernel - Re: [PATCH 1/4] dt-bindings: thermal: mediatek: Add AP domain to LVTS thermal controllers for mt8195

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Message-ID: <59fc344b-4d1a-e0b2-92b5-2341b014ae11@linaro.org>
Date:   Fri, 17 Mar 2023 12:57:28 +0100
From:   Daniel Lezcano <daniel.lezcano@...aro.org>
To:     Rob Herring <robh@...nel.org>
Cc:     Chen-Yu Tsai <wenst@...omium.org>, bchihi@...libre.com,
        angelogioacchino.delregno@...labora.com, rafael@...nel.org,
        amitk@...nel.org, rui.zhang@...el.com, matthias.bgg@...il.com,
        krzysztof.kozlowski+dt@...aro.org, rdunlap@...radead.org,
        ye.xingchen@....com.cn, p.zabel@...gutronix.de,
        linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org, devicetree@...r.kernel.org,
        khilman@...libre.com, james.lo@...iatek.com,
        rex-bc.chen@...iatek.com
Subject: Re: [PATCH 1/4] dt-bindings: thermal: mediatek: Add AP domain to LVTS
 thermal controllers for mt8195


Hi Rob,

On 16/03/2023 23:35, Rob Herring wrote:
> On Thu, Mar 09, 2023 at 11:39:13AM +0100, Daniel Lezcano wrote:
>> On 09/03/2023 05:40, Chen-Yu Tsai wrote:
>>> On Wed, Mar 8, 2023 at 12:46 AM <bchihi@...libre.com> wrote:
>>>>
>>>> From: Balsam CHIHI <bchihi@...libre.com>
>>>>
>>>> Add AP Domain to LVTS thermal controllers dt-binding definition for mt8195.
>>>>
>>>> Signed-off-by: Balsam CHIHI <bchihi@...libre.com>
>>>> ---
>>>>    include/dt-bindings/thermal/mediatek,lvts-thermal.h | 10 ++++++++++
>>>>    1 file changed, 10 insertions(+)
>>>>
>>>> diff --git a/include/dt-bindings/thermal/mediatek,lvts-thermal.h b/include/dt-bindings/thermal/mediatek,lvts-thermal.h
>>>> index c09398920468..8fa5a46675c4 100644
>>>> --- a/include/dt-bindings/thermal/mediatek,lvts-thermal.h
>>>> +++ b/include/dt-bindings/thermal/mediatek,lvts-thermal.h
>>>> @@ -16,4 +16,14 @@
>>>>    #define MT8195_MCU_LITTLE_CPU2  6
>>>>    #define MT8195_MCU_LITTLE_CPU3  7
>>>>
>>>> +#define MT8195_AP_VPU0  8
>>>
>>> Can't this start from 0? This is a different hardware block. The index
>>> namespace is separate. Same question for MT8192.
>>
>> The ID is used to differentiate the thermal zone identifier in the device
>> tree from the driver.
>>
>> +		vpu0-thermal {
>> +			polling-delay = <0>;
>> +			polling-delay-passive = <0>;
>> +			thermal-sensors = <&lvts_ap MT8195_AP_VPU0>;
>> +
>> +			trips {
>> +				vpu0_crit: trip-crit {
>> +					temperature = <100000>;
>> +					hysteresis = <2000>;
>> +					type = "critical";
>> +				};
>> +			};
>> +		};
>>
>> If MT8195_AP_VPU0 is 0, then the code won't be able to differentiate
>> MT8195_AP_VPU0 and MT8195_MCU_BIG_CPU0
>>
>> The LVTS driver will call devm_thermal_of_zone_register() with the sensor
>> id. If MT8195_MCU_BIG_CPU0 and MT8195_AP_VPU0 have the same id, then at the
>> moment of registering the MT8195_AP_VPU0, the underlying OF thermal
>> framework code will use MT8195_MCU_BIG_CPU0 description instead because it
>> will be the first to be find in the DT.
>>
>> If MT8195_AP_VPU0 is described in DT before, then the same will happen when
>> registering MT8195_MCU_BIG_CPU0, MT8195_AP_VPU0 will be registered instead.
>>
>> IOW all ids must be different.
> 
> That's broken for how producer/consumer phandle+args bindings work.

Do you mean this is broken for thermal zone description in the DT in 
general ?

What would be the correct approach ?



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