Re: [PATCH v2 15/15] arm64: dts: mediatek: mt8188: add default thermal zones

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Hi Nico,

a few comments about this description.

On 02/04/2024 05:25, Nicolas Pitre wrote:
From: Nicolas Pitre <npitre@xxxxxxxxxxxx>

Inspired by the vendor kernel but adapted to the upstream thermal
driver version.

[ ... ]

+	thermal_zones: thermal-zones {
+		cpu-little0-thermal {
+			polling-delay = <1000>;

Except if I'm wrong, the driver supports the interrupt mode, so it not necessary to poll constantly when there is no mitigation. You can remove the line and everywhere else.

+			polling-delay-passive = <250>;

As little CPU, 200ms or 150ms may be more adequate.

+			thermal-sensors = <&lvts_mcu MT8188_MCU_LITTLE_CPU0>;
+
+			trips {
+				cpu_little0_alert: trip-alert {
+					temperature = <85000>;
+					hysteresis = <2000>;
+					type = "passive";
+				};

You may want to add a 'hot' trip point in between, so the userspace can be notified and take an action before reaching 'critical' (like unplugging a CPU)

+				cpu_little0_crit: trip-crit {
+					temperature = <100000>;
+					hysteresis = <2000>;

critical is a point of no return. Hysteresis does not make sense.

These comments apply to all thermal zones.

[ .. ]

+		cpu_big0-thermal {
+			polling-delay = <1000>;
+			polling-delay-passive = <250>;

Same comments as the little but may be an even lower value. eg. 100ms.

+			thermal-sensors = <&lvts_mcu MT8188_MCU_BIG_CPU0>;
+
+			trips {
+				cpu_big0_alert: trip-alert {
+					temperature = <85000>;
+					hysteresis = <2000>;
+					type = "passive";
+				};
+
+				cpu_big0_crit: trip-crit {
+					temperature = <100000>;
+					hysteresis = <2000>;
+					type = "critical";
+				};
+			};
+
+			cooling-maps {
+				map0 {
+					trip = <&cpu_big0_alert>;
+					cooling-device = <&cpu6 THERMAL_NO_LIMIT THERMAL_NO_LIMIT>,
+							 <&cpu7 THERMAL_NO_LIMIT THERMAL_NO_LIMIT>;
+				};
+			};
+		};

[ ... ]

+		gpu1-thermal {
+			polling-delay = <1000>;
+			polling-delay-passive = <250>;
+			thermal-sensors = <&lvts_ap MT8188_AP_GPU1>;
+
+			trips {
+				gpu1_alert: trip-alert {
+					temperature = <85000>;
+					hysteresis = <2000>;
+					type = "passive";
+				};
+
+				gpu1_crit: trip-crit {
+					temperature = <100000>;
+					hysteresis = <2000>;
+					type = "critical";
+				};
+			};
+		};
+
+		gpu2-thermal {
+			polling-delay = <1000>;
+			polling-delay-passive = <250>;
+			thermal-sensors = <&lvts_ap MT8188_AP_GPU2>;
+
+			trips {
+				gpu2_alert: trip-alert {
+					temperature = <85000>;
+					hysteresis = <2000>;
+					type = "passive";
+				};
+
+				gpu2_crit: trip-crit {
+					temperature = <100000>;
+					hysteresis = <2000>;
+					type = "critical";
+				};
+			};

You can add a devfreq cooling device for the GPU here.

[ ... ]

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