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

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Date:   Fri, 10 Mar 2023 11:20:53 +0800
From:   Chen-Yu Tsai <wenst@...omium.org>
To:     Daniel Lezcano <daniel.lezcano@...aro.org>
Cc:     bchihi@...libre.com, angelogioacchino.delregno@...labora.com,
        rafael@...nel.org, amitk@...nel.org, rui.zhang@...el.com,
        matthias.bgg@...il.com, robh+dt@...nel.org,
        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

On Thu, Mar 9, 2023 at 6:39 PM Daniel Lezcano <daniel.lezcano@...aro.org> 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.

I see. I didn't realize the lookup namespace covered the whole platform.
In that case, please ignore my request.

ChenYu

> The namespace is already described by the macro name AFAICS, so whatever
> the values, we see only the macro names and those IDs are private the
> kernel implementation.
>
> If the numbering is really important, may be something like:
>
> #define MT8195_MCU_BIG_CPU0     00
> #define MT8195_MCU_BIG_CPU1     01
> #define MT8195_MCU_BIG_CPU2     02
> #define MT8195_MCU_BIG_CPU3     03
> #define MT8195_MCU_LITTLE_CPU0  04
> #define MT8195_MCU_LITTLE_CPU1  05
> #define MT8195_MCU_LITTLE_CPU2  06
> #define MT8195_MCU_LITTLE_CPU3  07
>
> #define MT8195_AP_VPU1  10
> #define MT8195_AP_GPU0  11
> #define MT8195_AP_GPU1  12
> #define MT8195_AP_VDEC  13
> #define MT8195_AP_IMG   14
> #define MT8195_AP_INFRA 15
> #define MT8195_AP_CAM0  16
> #define MT8195_AP_CAM1  17
>
> But I would suggest considering this change as a separate patch after
> the AP domain is added.
>
>
> --
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