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From: Alexey Charkov <alchark@gmail.com>
Date: Fri, 1 Mar 2024 09:20:04 +0400
Message-ID: <CABjd4YzFuhfS9RhJ6svb9ZD0NqMT5B6GmqigHFLr8YG6FR5k=w@mail.gmail.com>
Subject: Re: [PATCH v3 1/5] arm64: dts: rockchip: enable built-in thermal
 monitoring on RK3588
To: Dragan Simic <dsimic@manjaro.org>
Cc: Rob Herring <robh+dt@kernel.org>, 
	Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>, Conor Dooley <conor+dt@kernel.org>, 
	Heiko Stuebner <heiko@sntech.de>, Daniel Lezcano <daniel.lezcano@linaro.org>, 
	Viresh Kumar <viresh.kumar@linaro.org>, Chen-Yu Tsai <wens@kernel.org>, devicetree@vger.kernel.org, 
	linux-arm-kernel@lists.infradead.org, linux-rockchip@lists.infradead.org, 
	linux-kernel@vger.kernel.org
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On Fri, Mar 1, 2024 at 1:11=E2=80=AFAM Dragan Simic <dsimic@manjaro.org> wr=
ote:
>
> Hello Alexey,
>
> Please see also some nitpicks below, which I forgot to mention in
> my earlier response.  I'm sorry for that.
>
> On 2024-02-29 20:26, Alexey Charkov wrote:
> > Include thermal zones information in device tree for RK3588 variants.
> >
> > This also enables the TSADC controller unconditionally on all boards
> > to ensure that thermal protections are in place via throttling and
> > emergency reset, once OPPs are added to enable CPU DVFS.
> >
> > The default settings (using CRU as the emergency reset mechanism)
> > should work on all boards regardless of their wiring, as CRU resets
> > do not depend on any external components. Boards that have the TSHUT
> > signal wired to the reset line of the PMIC may opt to switch to GPIO
> > tshut mode instead (rockchip,hw-tshut-mode =3D <1>;)
> >
> > It seems though that downstream kernels don't use that, even for
> > those boards where the wiring allows for GPIO based tshut, such as
> > Radxa Rock 5B [1], [2], [3]
> >
> > [1]
> > https://github.com/radxa/kernel/blob/stable-5.10-rock5/arch/arm64/boot/=
dts/rockchip/rk3588-rock-5b.dts#L540
> > [2]
> > https://github.com/radxa/kernel/blob/stable-5.10-rock5/arch/arm64/boot/=
dts/rockchip/rk3588s.dtsi#L5433
> > [3] https://dl.radxa.com/rock5/5b/docs/hw/radxa_rock_5b_v1423_sch.pdf
> > page 11 (TSADC_SHUT_H)
> >
> > Signed-off-by: Alexey Charkov <alchark@gmail.com>
> > ---
> >  arch/arm64/boot/dts/rockchip/rk3588s.dtsi | 176
> > +++++++++++++++++++++++++++++-
> >  1 file changed, 175 insertions(+), 1 deletion(-)
> >
> > diff --git a/arch/arm64/boot/dts/rockchip/rk3588s.dtsi
> > b/arch/arm64/boot/dts/rockchip/rk3588s.dtsi
> > index 36b1b7acfe6a..9bf197358642 100644
> > --- a/arch/arm64/boot/dts/rockchip/rk3588s.dtsi
> > +++ b/arch/arm64/boot/dts/rockchip/rk3588s.dtsi
> > @@ -10,6 +10,7 @@
> >  #include <dt-bindings/reset/rockchip,rk3588-cru.h>
> >  #include <dt-bindings/phy/phy.h>
> >  #include <dt-bindings/ata/ahci.h>
> > +#include <dt-bindings/thermal/thermal.h>
> >
> >  / {
> >       compatible =3D "rockchip,rk3588";
> > @@ -2225,7 +2226,180 @@ tsadc: tsadc@fec00000 {
> >               pinctrl-1 =3D <&tsadc_shut>;
> >               pinctrl-names =3D "gpio", "otpout";
> >               #thermal-sensor-cells =3D <1>;
> > -             status =3D "disabled";
> > +             status =3D "okay";
> > +     };
> > +
> > +     thermal_zones: thermal-zones {
> > +             /* sensor near the center of the SoC */
> > +             package_thermal: package-thermal {
> > +                     polling-delay-passive =3D <0>;
> > +                     polling-delay =3D <0>;
> > +                     thermal-sensors =3D <&tsadc 0>;
> > +
> > +                     trips {
> > +                             package_crit: package-crit {
> > +                                     temperature =3D <115000>;
> > +                                     hysteresis =3D <0>;
> > +                                     type =3D "critical";
> > +                             };
> > +                     };
> > +             };
> > +
> > +             /* sensor between A76 cores 0 and 1 */
> > +             bigcore0_thermal: bigcore0-thermal {
> > +                     polling-delay-passive =3D <100>;
> > +                     polling-delay =3D <0>;
> > +                     thermal-sensors =3D <&tsadc 1>;
> > +
> > +                     trips {
> > +                             /* threshold to start collecting temperat=
ure
> > +                              * statistics e.g. with the IPA governor
> > +                              */
>
> See, I'm not a native English speaker, but I've spent a lot of time
> and effort improving my English skills.  Thus, perhaps these comments
> may or may not seem like unnecessary nitpicking, depending on how much
> someone pays attention to writing style in general, but I'll risk to
> be annoying and state these comments anyway. :)
>
> The comment above could be written in a much more condensed form like
> this, which would also be a bit more accurate:
>
>
>                                 /* IPA threshold, when IPA governor is us=
ed */
>
> IOW, we're writing all this for someone to read later, but we should
> (and can) perfectly reasonably expect some already existing background
> knowledge from the readers.  In other words, we should be as concise
> as possible.

In fact, the power allocation governor code itself doesn't call those
trips threshold or target as your suggested wording would imply.
Instead, it calls them "switch on temperature" and "maximum desired
temperature" [1]. Maybe we can call them that in the comments (and
also avoid calling the governor IPA, because upstream code only calls
it a "power allocator").

Best regards,
Alexey

[1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree=
/drivers/thermal/gov_power_allocator.c#n483

> > +                             bigcore0_alert0: bigcore0-alert0 {
> > +                                     temperature =3D <75000>;
> > +                                     hysteresis =3D <2000>;
> > +                                     type =3D "passive";
> > +                             };
> > +                             /* actual control temperature */
>
> Similarly to the above, I'd suggest this:
>
>                                 /* IPA target, when IPA governor is used =
*/
>
> Having such brief comments should make it all perfectly understandable
> to anyone who's already familiar with the way IPA governor works.
> Everyone
> else should be welcome to read up a bit on IPA first.
>
> > +                             bigcore0_alert1: bigcore0-alert1 {
> > +                                     temperature =3D <85000>;
> > +                                     hysteresis =3D <2000>;
> > +                                     type =3D "passive";
> > +                             };
> > +                             bigcore0_crit: bigcore0-crit {
> > +                                     temperature =3D <115000>;
> > +                                     hysteresis =3D <0>;
> > +                                     type =3D "critical";
> > +                             };
> > +                     };
> > +                     cooling-maps {
> > +                             map0 {
> > +                                     trip =3D <&bigcore0_alert1>;
> > +                                     cooling-device =3D
> > +                                             <&cpu_b0 THERMAL_NO_LIMIT=
 THERMAL_NO_LIMIT>,
> > +                                             <&cpu_b1 THERMAL_NO_LIMIT=
 THERMAL_NO_LIMIT>;
> > +                             };
> > +                     };
> > +             };
> > +
> > +             /* sensor between A76 cores 2 and 3 */
> > +             bigcore2_thermal: bigcore2-thermal {
> > +                     polling-delay-passive =3D <100>;
> > +                     polling-delay =3D <0>;
> > +                     thermal-sensors =3D <&tsadc 2>;
> > +
> > +                     trips {
> > +                             /* threshold to start collecting temperat=
ure
> > +                              * statistics e.g. with the IPA governor
> > +                              */
>
> The same as above.
>
> > +                             bigcore2_alert0: bigcore2-alert0 {
> > +                                     temperature =3D <75000>;
> > +                                     hysteresis =3D <2000>;
> > +                                     type =3D "passive";
> > +                             };
> > +                             /* actual control temperature */
>
> The same as above.
>
> > +                             bigcore2_alert1: bigcore2-alert1 {
> > +                                     temperature =3D <85000>;
> > +                                     hysteresis =3D <2000>;
> > +                                     type =3D "passive";
> > +                             };
> > +                             bigcore2_crit: bigcore2-crit {
> > +                                     temperature =3D <115000>;
> > +                                     hysteresis =3D <0>;
> > +                                     type =3D "critical";
> > +                             };
> > +                     };
> > +                     cooling-maps {
> > +                             map0 {
> > +                                     trip =3D <&bigcore2_alert1>;
> > +                                     cooling-device =3D
> > +                                             <&cpu_b2 THERMAL_NO_LIMIT=
 THERMAL_NO_LIMIT>,
> > +                                             <&cpu_b3 THERMAL_NO_LIMIT=
 THERMAL_NO_LIMIT>;
> > +                             };
> > +                     };
> > +             };
> > +
> > +             /* sensor between the four A55 cores */
> > +             little_core_thermal: littlecore-thermal {
> > +                     polling-delay-passive =3D <100>;
> > +                     polling-delay =3D <0>;
> > +                     thermal-sensors =3D <&tsadc 3>;
> > +
> > +                     trips {
> > +                             /* threshold to start collecting temperat=
ure
> > +                              * statistics e.g. with the IPA governor
> > +                              */
>
> The same as above.
>
> > +                             littlecore_alert0: littlecore-alert0 {
> > +                                     temperature =3D <75000>;
> > +                                     hysteresis =3D <2000>;
> > +                                     type =3D "passive";
> > +                             };
> > +                             /* actual control temperature */
>
> The same as above.
>
> > +                             littlecore_alert1: littlecore-alert1 {
> > +                                     temperature =3D <85000>;
> > +                                     hysteresis =3D <2000>;
> > +                                     type =3D "passive";
> > +                             };
> > +                             littlecore_crit: littlecore-crit {
> > +                                     temperature =3D <115000>;
> > +                                     hysteresis =3D <0>;
> > +                                     type =3D "critical";
> > +                             };
> > +                     };
> > +                     cooling-maps {
> > +                             map0 {
> > +                                     trip =3D <&littlecore_alert1>;
> > +                                     cooling-device =3D
> > +                                             <&cpu_l0 THERMAL_NO_LIMIT=
 THERMAL_NO_LIMIT>,
> > +                                             <&cpu_l1 THERMAL_NO_LIMIT=
 THERMAL_NO_LIMIT>,
> > +                                             <&cpu_l2 THERMAL_NO_LIMIT=
 THERMAL_NO_LIMIT>,
> > +                                             <&cpu_l3 THERMAL_NO_LIMIT=
 THERMAL_NO_LIMIT>;
> > +                             };
> > +                     };
> > +             };
> > +
> > +             /* sensor near the PD_CENTER power domain */
> > +             center_thermal: center-thermal {
> > +                     polling-delay-passive =3D <0>;
> > +                     polling-delay =3D <0>;
> > +                     thermal-sensors =3D <&tsadc 4>;
> > +
> > +                     trips {
> > +                             center_crit: center-crit {
> > +                                     temperature =3D <115000>;
> > +                                     hysteresis =3D <0>;
> > +                                     type =3D "critical";
> > +                             };
> > +                     };
> > +             };
> > +
> > +             gpu_thermal: gpu-thermal {
> > +                     polling-delay-passive =3D <0>;
> > +                     polling-delay =3D <0>;
> > +                     thermal-sensors =3D <&tsadc 5>;
> > +
> > +                     trips {
> > +                             gpu_crit: gpu-crit {
> > +                                     temperature =3D <115000>;
> > +                                     hysteresis =3D <0>;
> > +                                     type =3D "critical";
> > +                             };
> > +                     };
> > +             };
> > +
> > +             npu_thermal: npu-thermal {
> > +                     polling-delay-passive =3D <0>;
> > +                     polling-delay =3D <0>;
> > +                     thermal-sensors =3D <&tsadc 6>;
> > +
> > +                     trips {
> > +                             npu_crit: npu-crit {
> > +                                     temperature =3D <115000>;
> > +                                     hysteresis =3D <0>;
> > +                                     type =3D "critical";
> > +                             };
> > +                     };
> > +             };
> >       };
> >
> >       saradc: adc@fec10000 {