On Wed, Mar 25, 2020 at 3:51 PM Lukasz Luba <lukasz.luba@xxxxxxx> wrote: > > Hi Amit, > > On 3/25/20 6:34 AM, Amit Kucheria wrote: > > As part of moving the thermal bindings to YAML, split it up into 3 > > bindings: thermal sensors, cooling devices and thermal zones. > > > > The property #cooling-cells is required in each device that acts as a > > cooling device - whether active or passive. So any device that can > > throttle its performance to passively reduce heat dissipation (e.g. > > cpus, gpus) and any device that can actively dissipate heat at different > > levels (e.g. fans) will contain this property. > > > > Signed-off-by: Amit Kucheria <amit.kucheria@xxxxxxxxxx> > > --- > > .../thermal/thermal-cooling-devices.yaml | 116 ++++++++++++++++++ > > 1 file changed, 116 insertions(+) > > create mode 100644 Documentation/devicetree/bindings/thermal/thermal-cooling-devices.yaml > > > > diff --git a/Documentation/devicetree/bindings/thermal/thermal-cooling-devices.yaml b/Documentation/devicetree/bindings/thermal/thermal-cooling-devices.yaml > > new file mode 100644 > > index 000000000000..b5599f7859f8 > > --- /dev/null > > +++ b/Documentation/devicetree/bindings/thermal/thermal-cooling-devices.yaml > > @@ -0,0 +1,116 @@ > > +# SPDX-License-Identifier: (GPL-2.0) > > +# Copyright 2020 Linaro Ltd. > > +%YAML 1.2 > > +--- > > +$id: http://devicetree.org/schemas/thermal/thermal-cooling-devices.yaml# > > +$schema: http://devicetree.org/meta-schemas/core.yaml# > > + > > +title: Thermal cooling device binding > > + > > +maintainers: > > + - Amit Kucheria <amitk@xxxxxxxxxx> > > + > > +description: | > > + Thermal management is achieved in devicetree by describing the sensor hardware > > + and the software abstraction of cooling devices and thermal zones required to > > + take appropriate action to mitigate thermal overload. > > + > > + The following node types are used to completely describe a thermal management > > + system in devicetree: > > + - thermal-sensor: device that measures temperature, has SoC-specific bindings > > + - cooling-device: device used to dissipate heat either passively or artively > > + - thermal-zones: a container of the following node types used to describe all > > + thermal data for the platform > > + > > + This binding describes the cooling devices. > > + > > + There are essentially two ways to provide control on power dissipation: > > + - Passive cooling: by means of regulating device performance. A typical > > + passive cooling mechanism is a CPU that has dynamic voltage and frequency > > + scaling (DVFS), and uses lower frequencies as cooling states. > > + - Active cooling: by means of activating devices in order to remove the > > + dissipated heat, e.g. regulating fan speeds. > > + > > + Any cooling device has a range of cooling states (i.e. different levels of > > + heat dissipation). They also have a way to determine the state of cooling in > > + which the device is. For example, a fan's cooling states correspond to the > > + different fan speeds possible. Cooling states are referred to by single > > + unsigned integers, where larger numbers mean greater heat dissipation. The > > + precise set of cooling states associated with a device should be defined in > > + a particular device's binding. > > [snip] > > > + > > + thermal-zones { > > + cpu0-thermal { > > + polling-delay-passive = <250>; > > + polling-delay = <1000>; > > + > > + thermal-sensors = <&tsens0 1>; > > + > > + trips { > > + cpu0_alert0: trip-point0 { > > + temperature = <90000>; > > + hysteresis = <2000>; > > + type = "passive"; > > + }; > > + }; > > + > > + cooling-maps { > > + map0 { > > + trip = <&cpu0_alert0>; > > + cooling-device = <&CPU0 THERMAL_NO_LIMIT > > + THERMAL_NO_LIMIT>; > > Maybe add something like this, to better reflect the description: > > trip = <&cpu0_alert0>; > /* Corresponds to 1000MHz in OPP table */ > cooling-device = <&CPU0 5 5>; > > This is less confusing than THERMAL_NO_LIMIT. Thanks for the review. Will fix.
