[PATCH v2 3/3] ARM: dts: rockchip: Configure the GPU thermal zone for mickey

[Matthias Kaehlcke]

mickey crams a lot of hardware into a tiny package, which requires
more aggressive thermal throttling than for devices with a larger
footprint. Configure the GPU thermal zone to throttle the GPU
progressively at temperatures >= 60ÂC. Heat dissipated by the
CPUs also affects the GPU temperature, hence we cap the CPU
frequency to 1.4 GHz for temperatures above 65ÂC. Further throttling
of the CPUs may be performed by the CPU thermal zone.

The configuration matches that of the downstream Chrome OS 3.14
kernel, the 'official' kernel for mickey.

Signed-off-by: Matthias Kaehlcke <mka@xxxxxxxxxxxx>
---
Changes in v2:
- specify all CPUs as cooling devices
- s/downstram/downstream/ in commit message

Note: this patch depends on "ARM: dts: rockchip: Add #cooling-cells
entry for rk3288 GPU" (https://lore.kernel.org/patchwork/patch/1075005/)
---
 arch/arm/boot/dts/rk3288-veyron-mickey.dts | 67 ++++++++++++++++++++++
 1 file changed, 67 insertions(+)

diff --git a/arch/arm/boot/dts/rk3288-veyron-mickey.dts b/arch/arm/boot/dts/rk3288-veyron-mickey.dts
index 34797abe3403..945e80801292 100644
--- a/arch/arm/boot/dts/rk3288-veyron-mickey.dts
+++ b/arch/arm/boot/dts/rk3288-veyron-mickey.dts
@@ -136,6 +136,73 @@
 	};
 };
 
+&gpu_thermal {
+	/delete-node/ trips;
+	/delete-node/ cooling-maps;
+
+	trips {
+		gpu_alert_warmish: gpu_alert_warmish {
+			temperature = <60000>; /* millicelsius */
+			hysteresis = <2000>; /* millicelsius */
+			type = "passive";
+		};
+		gpu_alert_warm: gpu_alert_warm {
+			temperature = <65000>; /* millicelsius */
+			hysteresis = <2000>; /* millicelsius */
+			type = "passive";
+		};
+		gpu_alert_hotter: gpu_alert_hotter {
+			temperature = <84000>; /* millicelsius */
+			hysteresis = <2000>; /* millicelsius */
+			type = "passive";
+		};
+		gpu_alert_very_very_hot: gpu_alert_very_very_hot {
+			temperature = <86000>; /* millicelsius */
+			hysteresis = <2000>; /* millicelsius */
+			type = "passive";
+		};
+		gpu_crit: gpu_crit {
+			temperature = <90000>; /* millicelsius */
+			hysteresis = <2000>; /* millicelsius */
+			type = "critical";
+		};
+	};
+
+	cooling-maps {
+		/* After 1st level throttle the GPU down to as low as 400 MHz */
+		gpu_warmish_limit_gpu {
+			trip = <&gpu_alert_warmish>;
+			cooling-device = <&gpu THERMAL_NO_LIMIT 1>;
+		};
+
+		/*
+		 * Slightly after we throttle the GPU, we'll also make sure that
+		 * the CPU can't go faster than 1.4 GHz.  Note that we won't
+		 * throttle the CPU lower than 1.4 GHz due to GPU heat--we'll
+		 * let the CPU do the rest itself.
+		 */
+		gpu_warm_limit_cpu {
+			trip = <&gpu_alert_warm>;
+			cooling-device = <&cpu0 4 4>,
+					 <&cpu1 4 4>,
+					 <&cpu2 4 4>,
+					 <&cpu3 4 4>;
+		};
+
+		/* When hot, GPU goes down to 300 MHz */
+		gpu_hotter_limit_gpu {
+			trip = <&gpu_alert_hotter>;
+			cooling-device = <&gpu 2 2>;
+		};
+
+		/* When really hot, don't let GPU go _above_ 300 MHz */
+		gpu_very_very_hot_limit_gpu {
+			trip = <&gpu_alert_very_very_hot>;
+			cooling-device = <&gpu 2 THERMAL_NO_LIMIT>;
+		};
+	};
+};
+
 &i2c2 {
 	status = "disabled";
 };
-- 
2.21.0.1020.gf2820cf01a-goog