[PATCH v2 15/15] ARM: tegra: nexus7: Improve thermal zones

Dmitry Osipenko
2021-08-02T21:21:28Z

Use skin temperature for maintaining temperature that is suitable
specifically for Nexus 7. Add CPU thermal zone that protects silicon.
All these changes don't make a significant difference, but it is a
more correct definition of thermal zones.

Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
---
.../tegra30-asus-nexus7-grouper-common.dtsi | 56 +++++++++++++++++--
1 file changed, 52 insertions(+), 4 deletions(-)

diff --git a/arch/arm/boot/dts/tegra30-asus-nexus7-grouper-common.dtsi b/arch/arm/boot/dts/tegra30-asus-nexus7-grouper-common.dtsi
index 33985fca956f..9732cd6f20b7 100644
--- a/arch/arm/boot/dts/tegra30-asus-nexus7-grouper-common.dtsi
+++ b/arch/arm/boot/dts/tegra30-asus-nexus7-grouper-common.dtsi
@@ -1255,21 +1255,34 @@ sound {
};

thermal-zones {
- cpu-thermal {
+ /*
+ * NCT72 has two sensors:
+ *
+ * 0: internal that monitors ambient/skin temperature
+ * 1: external that is connected to the CPU's diode
+ *
+ * Ideally we should use userspace thermal governor,
+ * but it's a much more complex solution. The "skin"
+ * zone is a simpler solution which prevents Nexus 7
+ * from getting too hot from a user's tactile perspective.
+ * The CPU zone is intended to protect silicon from damage.
+ */
+
+ skin-thermal {
polling-delay-passive = <1000>; /* milliseconds */
polling-delay = <5000>; /* milliseconds */

- thermal-sensors = <&nct72 1>;
+ thermal-sensors = <&nct72 0>;

trips {
- trip0: cpu-alert0 {
+ trip0: skin-alert {
/* throttle at 57C until temperature drops to 56.8C */
temperature = <57000>;
hysteresis = <200>;
type = "passive";
};

- trip1: cpu-crit {
+ trip1: skin-crit {
/* shut down at 65C */
temperature = <65000>;
hysteresis = <2000>;
@@ -1289,5 +1302,40 @@ map0 {
};
};
};
+
+ cpu-thermal {
+ polling-delay-passive = <1000>; /* milliseconds */
+ polling-delay = <5000>; /* milliseconds */
+
+ thermal-sensors = <&nct72 1>;
+
+ trips {
+ trip2: cpu-alert {
+ /* throttle at 85C until temperature drops to 84.8C */
+ temperature = <85000>;
+ hysteresis = <200>;
+ type = "passive";
+ };
+
+ trip3: cpu-crit {
+ /* shut down at 90C */
+ temperature = <90000>;
+ hysteresis = <2000>;
+ type = "critical";
+ };
+ };
+
+ cooling-maps {
+ map1 {
+ trip = <&trip2>;
+ cooling-device = <&cpu0 THERMAL_NO_LIMIT THERMAL_NO_LIMIT>,
+ <&cpu1 THERMAL_NO_LIMIT THERMAL_NO_LIMIT>,
+ <&cpu2 THERMAL_NO_LIMIT THERMAL_NO_LIMIT>,
+ <&cpu3 THERMAL_NO_LIMIT THERMAL_NO_LIMIT>,
+ <&actmon THERMAL_NO_LIMIT
+ THERMAL_NO_LIMIT>;
+ };
+ };
+ };
};
};
--
2.32.0