Re: [EXT] Re: [PATCH 1/2] arm64: dts: ls1088a: add more thermal zone support

From: Amit Kucheria
Date: Tue Jun 30 2020 - 02:47:02 EST

On Tue, Jun 30, 2020 at 12:07 PM Andy Tang <andy.tang@xxxxxxx> wrote:
>
>
>
> > -----Original Message-----
> > From: Amit Kucheria <amit.kucheria@xxxxxxxxxx>
> > Sent: 2020å6æ30æ 13:37
> > To: Andy Tang <andy.tang@xxxxxxx>
> > Cc: Shawn Guo <shawnguo@xxxxxxxxxx>; Leo Li <leoyang.li@xxxxxxx>; Rob
> > Herring <robh+dt@xxxxxxxxxx>; lakml <linux-arm-kernel@xxxxxxxxxxxxxxxxxxx>;
> > open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS
> > <devicetree@xxxxxxxxxxxxxxx>; LKML <linux-kernel@xxxxxxxxxxxxxxx>
> > Subject: Re: [EXT] Re: [PATCH 1/2] arm64: dts: ls1088a: add more thermal
> > zone support
> >
> > Caution: EXT Email
> >
> > On Tue, Jun 30, 2020 at 10:58 AM Andy Tang <andy.tang@xxxxxxx> wrote:
> > >
> > >
> > >
> > > > -----Original Message-----
> > > > From: Amit Kucheria <amit.kucheria@xxxxxxxxxx>
> > > > Sent: 2020å6æ30æ 13:12
> > > > To: Andy Tang <andy.tang@xxxxxxx>
> > > > Cc: Shawn Guo <shawnguo@xxxxxxxxxx>; Leo Li <leoyang.li@xxxxxxx>;
> > > > Rob Herring <robh+dt@xxxxxxxxxx>; lakml
> > > > <linux-arm-kernel@xxxxxxxxxxxxxxxxxxx>;
> > > > open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS
> > > > <devicetree@xxxxxxxxxxxxxxx>; LKML <linux-kernel@xxxxxxxxxxxxxxx>
> > > > Subject: [EXT] Re: [PATCH 1/2] arm64: dts: ls1088a: add more thermal
> > > > zone support
> > > >
> > > > Caution: EXT Email
> > > >
> > > > On Tue, Jun 30, 2020 at 8:56 AM <andy.tang@xxxxxxx> wrote:
> > > > >
> > > > > From: Yuantian Tang <andy.tang@xxxxxxx>
> > > > >
> > > > > There are 2 thermal zones in ls1088a soc. Add the other thermal
> > > > > zone node to enable it.
> > > > > Also update the values in calibration table to make the
> > > > > temperatures monitored more precise.
> > > > >
> > > > > Signed-off-by: Yuantian Tang <andy.tang@xxxxxxx>
> > > > > ---
> > > > > .../arm64/boot/dts/freescale/fsl-ls1088a.dtsi | 100
> > > > > +++++++++++-------
> > > > > 1 file changed, 62 insertions(+), 38 deletions(-)
> > > > >
> > > > > diff --git a/arch/arm64/boot/dts/freescale/fsl-ls1088a.dtsi
> > > > > b/arch/arm64/boot/dts/freescale/fsl-ls1088a.dtsi
> > > > > index 36a799554620..ccbbc23e6c85 100644
> > > > > --- a/arch/arm64/boot/dts/freescale/fsl-ls1088a.dtsi
> > > > > +++ b/arch/arm64/boot/dts/freescale/fsl-ls1088a.dtsi
> > > > > @@ -129,19 +129,19 @@
> > > > > };
> > > > >
> > > > > thermal-zones {
> > > > > - cpu_thermal: cpu-thermal {
> > > > > + core-cluster {
> > > > > polling-delay-passive = <1000>;
> > > > > polling-delay = <5000>;
> > > > > thermal-sensors = <&tmu 0>;
> > > > >
> > > > > trips {
> > > > > - cpu_alert: cpu-alert {
> > > > > + core_cluster_alert:
> > > > core-cluster-alert
> > > > > + {
> > > > > temperature =
> > <85000>;
> > > > > hysteresis = <2000>;
> > > > > type = "passive";
> > > > > };
> > > > >
> > > > > - cpu_crit: cpu-crit {
> > > > > + core_cluster_crit:
> > > > > + core-cluster-crit {
> > > > > temperature =
> > <95000>;
> > > > > hysteresis = <2000>;
> > > > > type = "critical"; @@
> > > > -150,7
> > > > > +150,7 @@
> > > > >
> > > > > cooling-maps {
> > > > > map0 {
> > > > > - trip = <&cpu_alert>;
> > > > > + trip =
> > > > <&core_cluster_alert>;
> > > > > cooling-device =
> > > > > <&cpu0
> > > > THERMAL_NO_LIMIT THERMAL_NO_LIMIT>,
> > > > > <&cpu1
> > > > > THERMAL_NO_LIMIT THERMAL_NO_LIMIT>, @@ -163,6 +163,26 @@
> > > > > };
> > > > > };
> > > > > };
> > > > > +
> > > > > + soc {
> > > > > + polling-delay-passive = <1000>;
> > > > > + polling-delay = <5000>;
> > > > > + thermal-sensors = <&tmu 1>;
> > > > > +
> > > > > + trips {
> > > > > + soc-alert {
> > > > > + temperature =
> > <85000>;
> > > > > + hysteresis = <2000>;
> > > > > + type = "passive";
> > > > > + };
> > > > > +
> > > > > + soc-crit {
> > > > > + temperature =
> > <95000>;
> > > > > + hysteresis = <2000>;
> > > > > + type = "critical";
> > > > > + };
> > > > > + };
> > > > > + };
> > > >
> > > > You should also add a cooling-maps section for this thermal zone
> > > > given that it has a passive trip type. Otherwise there is no use for a
> > passive trip type.
> > > It is better to have a cooling device. But there is only one cooling
> > > device on this platform which is used by core-cluster. So there is no extra
> > cooling device for it.
> > > This zone can take action when critical temp is reached. So it is still useful.
> > > What do you suggest?
> >
> > If the action taken by the core-cluster cooling-maps is the only one that can
> > be taken, I suggest getting rid of the the soc-alert passive trip completely. It is
> > not of any use.
> >
> > If there is a chance that your soc thermal-zone can heat up before your
> > cpu-cluster zone (unlikely), you could use the same cooling device (cpu0, cpu1)
> > for soc thermal zone too.
> Thanks for your suggestion.
> I was told that a cooling-maps can not be applied to more than one thermal zone.
> So the only option is to remove the alert trip.

The cooling-map is unique to the thermal-zone. But the cooling devices
may be reused.

See arch/arm64/boot/dts/qcom/sdm845.dtsi for an example.

So, in your case, you would have a cooling-map section that ties the
soc-alert trip to the same cooling devices as in cpu-cluster cooling
map.