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Date: Fri, 1 Mar 2024 11:51:56 +0400
From: Alexey Charkov <alchark@...il.com>
To: Dragan Simic <dsimic@...jaro.org>
Cc: Rob Herring <robh+dt@...nel.org>,
Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>, Conor Dooley <conor+dt@...nel.org>,
Heiko Stuebner <heiko@...ech.de>, Daniel Lezcano <daniel.lezcano@...aro.org>,
Viresh Kumar <viresh.kumar@...aro.org>, Chen-Yu Tsai <wens@...nel.org>, devicetree@...r.kernel.org,
linux-arm-kernel@...ts.infradead.org, linux-rockchip@...ts.infradead.org,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 1/5] arm64: dts: rockchip: enable built-in thermal
monitoring on RK3588
On Fri, Mar 1, 2024 at 10:14 AM Dragan Simic <dsimic@...jaro.org> wrote:
>
> On 2024-03-01 06:20, Alexey Charkov wrote:
> > On Fri, Mar 1, 2024 at 1:11 AM Dragan Simic <dsimic@...jaro.org> wrote:
> >> 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 = <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@...il.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 = "rockchip,rk3588";
> >> > @@ -2225,7 +2226,180 @@ tsadc: tsadc@...00000 {
> >> > pinctrl-1 = <&tsadc_shut>;
> >> > pinctrl-names = "gpio", "otpout";
> >> > #thermal-sensor-cells = <1>;
> >> > - status = "disabled";
> >> > + status = "okay";
> >> > + };
> >> > +
> >> > + thermal_zones: thermal-zones {
> >> > + /* sensor near the center of the SoC */
> >> > + package_thermal: package-thermal {
> >> > + polling-delay-passive = <0>;
> >> > + polling-delay = <0>;
> >> > + thermal-sensors = <&tsadc 0>;
> >> > +
> >> > + trips {
> >> > + package_crit: package-crit {
> >> > + temperature = <115000>;
> >> > + hysteresis = <0>;
> >> > + type = "critical";
> >> > + };
> >> > + };
> >> > + };
> >> > +
> >> > + /* sensor between A76 cores 0 and 1 */
> >> > + bigcore0_thermal: bigcore0-thermal {
> >> > + polling-delay-passive = <100>;
> >> > + polling-delay = <0>;
> >> > + thermal-sensors = <&tsadc 1>;
> >> > +
> >> > + trips {
> >> > + /* threshold to start collecting temperature
> >> > + * 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
> >> used */
> >>
> >> 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").
>
> Hmm, but "IPA" is still mentioned in exactly three places in the files
> under drivers/thermal. I think that warrants the use of "IPA", which
> is also widely used pretty much everywhere.
>
> Perhaps a win-win would be to have only the very first of the comments
> like this, to introduce "IPA" as an acronym:
>
> /* Power allocator (IPA) thermal
> governor */
> /* switch-on point, when IPA governor
> is used */
Yes, good point, thanks!
> Next, "the target temperature" is mentioned more than a few times in
> drivers/thermal/gov_power_allocator.c, which I believe makes the use
> of "IPA target" perfectly valid. Actually, let's use "IPA target
> temperature", if you agree, to make it self descriptive.
Or perhaps simply "target temperature"? Stepwise governor will also
use this trip as its target, so it's not IPA specific, unlike the
switch-on point.
> Finally, the threshold... Based on
> drivers/thermal/gov_power_allocator.c,
> I think "IPA switch-on point" would be a good choice, which I already
> used above in the proposed opening comment.
Agreed, that sounds good to me, will reflect in the next iteration.
Thanks for bringing it up!
Best,
Alexey
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