On Tue, Aug 11, 2020 at 08:31:15PM +0800, Finley Xiao wrote:
The default value for k_pu is:
2 * sustainable_power / (desired_temperature - switch_on_temp)
The default value for k_po is:
sustainable_power / (desired_temperature - switch_on_temp)
The default value for k_i is 10.
Even though these parameters of the PID controller can be changed
by the following sysfs files:
/sys/class/thermal/thermal_zoneX/k_pu
/sys/class/thermal/thermal_zoneX/k_po
/sys/class/thermal/thermal_zoneX/k_i
But it's still more convenient to change the default values by devicetree,
so introduce these three optional properties. If provided these properties,
they will be parsed and associated with the thermal zone via the thermal
zone parameters.
Signed-off-by: Finley Xiao <finley.xiao@xxxxxxxxxxxxxx>
---
Documentation/devicetree/bindings/thermal/thermal.txt | 14 ++++++++++++++
Bindings should be a separate file and this one is a DT schema now.
drivers/thermal/thermal_of.c | 7 +++++++
2 files changed, 21 insertions(+)
diff --git a/Documentation/devicetree/bindings/thermal/thermal.txt b/Documentation/devicetree/bindings/thermal/thermal.txt
index f78bec19ca35..ebe936b57ded 100644
--- a/Documentation/devicetree/bindings/thermal/thermal.txt
+++ b/Documentation/devicetree/bindings/thermal/thermal.txt
@@ -165,6 +165,20 @@ Optional property:
2000mW, while on a 10'' tablet is around
4500mW.
+- k-po: Proportional parameter of the PID controller when
+ current temperature is above the target.
+ Type: signed
+ Size: one cell
+
+- k-pu: Proportional parameter of the PID controller when
+ current temperature is below the target.
+ Type: signed
+ Size: one cell
+
+- k-i: Integral parameter of the PID controller.
+ Type: signed
+ Size: one cell
What's PID?
I know nothing about the sysfs params, but the binding needs to stand on
it's own and needs enough detail to educate me.