linux-kernel - [PATCH] Fix mt7622.dtsi thermal cpu

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Date:   Sat, 19 Jun 2021 14:19:26 +0200
From:   ericwouds@...il.com
To:     Rob Herring <robh+dt@...nel.org>,
        Matthias Brugger <matthias.bgg@...il.com>
Cc:     Eric Woudstra <ericwouds@...il.com>, devicetree@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: [PATCH] Fix mt7622.dtsi thermal cpu

From: Eric Woudstra <ericwouds@...il.com>

Cpu-thermal is set to use all frequencies already at 47 degrees. 
Using the CPU at 50 for a minute, the CPU has reached 48 degrees, is 
throttled back to lowest setting, making the mt7622 terrribly slow. 
Even at this low speed, the CPU does not cool down lower then 47 so
the CPU is stuck at lowest possible frequency until it shut down and
stays off for 15 minutes.

cooling-device = <&cpu0 THERMAL_NO_LIMIT THERMAL_NO_LIMIT>,
                 <&cpu1 THERMAL_NO_LIMIT THERMAL_NO_LIMIT>;

This should not be set al every cooling map. It should only be set at
the highest cooling map. Same as in the example:

https://www.kernel.org/doc/Documentation/devicetree/bindings/
thermal/thermal.txt  line 272

But then without the fan and added a third map.

Now temperature will be regulated at 87 degrees celcius. At temperatures
lower then 87, all frequencies can be used.

Also see the post:

http://forum.banana-pi.org/t/bpi-r64-only-10-cpu-speed-at-already-48-
degrees-celcius-speed-not-increasing-anymore/12262

Signed-off-by: Eric Woudstra <ericwouds@...il.com>
---
 arch/arm64/boot/dts/mediatek/mt7622.dtsi | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/arch/arm64/boot/dts/mediatek/mt7622.dtsi b/arch/arm64/boot/dts/mediatek/mt7622.dtsi
index 890a942ec..b779c7aa6 100644
--- a/arch/arm64/boot/dts/mediatek/mt7622.dtsi
+++ b/arch/arm64/boot/dts/mediatek/mt7622.dtsi
@@ -170,14 +170,14 @@ cpu-crit {
 			cooling-maps {
 				map0 {
 					trip = <&cpu_passive>;
-					cooling-device = <&cpu0 THERMAL_NO_LIMIT THERMAL_NO_LIMIT>,
-							 <&cpu1 THERMAL_NO_LIMIT THERMAL_NO_LIMIT>;
+					cooling-device = <&cpu0 0 0>,
+							 <&cpu1 0 0>;
 				};
 
 				map1 {
 					trip = <&cpu_active>;
-					cooling-device = <&cpu0 THERMAL_NO_LIMIT THERMAL_NO_LIMIT>,
-							 <&cpu1 THERMAL_NO_LIMIT THERMAL_NO_LIMIT>;
+					cooling-device = <&cpu0 0 0>,
+							 <&cpu1 0 0>;
 				};
 
 				map2 {
-- 
2.25.1