linux-kernel - [PATCH 1/2] ARM: dts: rockchip: Limit GPU frequency on veyron mickey to 300 MHz when the CPU gets very hot

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Message-Id: <20190520170132.91571-1-mka@chromium.org>
Date:   Mon, 20 May 2019 10:01:31 -0700
From:   Matthias Kaehlcke <mka@...omium.org>
To:     Heiko Stuebner <heiko@...ech.de>, Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>
Cc:     linux-arm-kernel@...ts.infradead.org,
        linux-rockchip@...ts.infradead.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Douglas Anderson <dianders@...omium.org>,
        Matthias Kaehlcke <mka@...omium.org>
Subject: [PATCH 1/2] ARM: dts: rockchip: Limit GPU frequency on veyron mickey to 300 MHz when the CPU gets very hot

On rk3288 the CPU and GPU temperatures are correlated. Limit the GPU
frequency on veyron mickey to 300 MHz for CPU temperatures >= 85°C.

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

Signed-off-by: Matthias Kaehlcke <mka@...omium.org>
---
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 | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/arch/arm/boot/dts/rk3288-veyron-mickey.dts b/arch/arm/boot/dts/rk3288-veyron-mickey.dts
index d889ab3c8235..f118d92a49d0 100644
--- a/arch/arm/boot/dts/rk3288-veyron-mickey.dts
+++ b/arch/arm/boot/dts/rk3288-veyron-mickey.dts
@@ -125,6 +125,12 @@
 					 <&cpu2 8 THERMAL_NO_LIMIT>,
 					 <&cpu3 8 THERMAL_NO_LIMIT>;
 		};
+
+		/* At very hot, don't let GPU go over 300 MHz */
+		cpu_very_hot_limit_gpu {
+			trip = <&cpu_alert_very_hot>;
+			cooling-device = <&gpu 2 2>;
+		};
 	};
 };
 
-- 
2.21.0.1020.gf2820cf01a-goog