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mediatek: fix pwn fan settings for sinovoip bpi-r3 (v3)

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Popular cheap PWM fans for this machine, like the ones coming in
heatsink+fan combos will not work properly at the currently defined
medium speed. Trying different pwm setting using a command

  echo $value > /sys/devices/platform/pwm-fan/hwmon/hwmon1/pwm1

I found:

  pwm1 value     fan rotation speed   cpu temperature     notes
  -----------------------------------------------------------------
    0            maximal              31.5 Celsius        too noisy
   40            optimal              35.2 Celsius        no noise hearable
   95            minimal
   above 95      does not rotate      55.5 Celsius
  -----------------------------------------------------------------

Current cooling levels are:

	cooling-levels = <255 96 0>;

Thus only cpu-active-high and cpu-active-low modes are usable.
This patch fixes cpu-active-medium settings for bpi-r3 board.

This patch may not be enough. Users may wants to tweak their thermal_zone0
trip points, thus tuning fan rotation speed depending on cpu temperature.
That can be done on the base of the following example:

  === example =========
  # cpu temperature below 25 Celsius degrees, no rotation
  echo 25000 > /sys/class/thermal/thermal_zone0/trip_point_4_temp
  # cpu temperature in [25..32] Celsius degrees, normal rotation speed
  echo 32000 > /sys/class/thermal/thermal_zone0/trip_point_3_temp
  # cpu temperature above 50 Celsius degrees, max rotation speed
  echo 50000 > /sys/class/thermal/thermal_zone0/trip_point_2_temp
  =====================

Changes v2:
* put patch to a proper directory
* updated patch description
* tested with latest openwrt based on linux-6.6

Changes v3:
* use upstream linux patch
* update patch description

Signed-off-by: Mikhail Kshevetskiy <mikhail.kshevetskiy@gmail.com>
Link: https://github.com/openwrt/openwrt/pull/17130
Signed-off-by: Robert Marko <robimarko@gmail.com>
This commit is contained in:
Mikhail Kshevetskiy 2024-11-22 01:29:06 +03:00 • committed by Robert Marko
parent def7548867
commit 095151b235
1 changed files with 72 additions and 0 deletions
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72
target/linux/mediatek/patches-6.12/061-v6.19-arm64-dts-mediatek-mt7986-bpi-r3-Change-fan-PWM-valu.patch Normal file
View file

@ -0,0 +1,72 @@
From 5f271fe1365b63f67fc384ca8d50d473d09de0d1 Mon Sep 17 00:00:00 2001
From: Mikhail Kshevetskiy <mikhail.kshevetskiy@iopsys.eu>
Date: Tue, 3 Dec 2024 07:33:55 +0300
Subject: [PATCH] arm64: dts: mediatek: mt7986-bpi-r3: Change fan PWM value for
mid speed
Popular cheap PWM fans for this machine, like the ones coming in
heatsink+fan combos will not work properly at the currently defined
medium speed. Trying different pwm setting using a command
echo $value > /sys/devices/platform/pwm-fan/hwmon/hwmon1/pwm1
I found:
pwm1 value fan rotation speed cpu temperature notes
-----------------------------------------------------------------
0 maximal 31.5 Celsius too noisy
40 optimal 35.2 Celsius no noise hearable
95 minimal
above 95 does not rotate 55.5 Celsius
-----------------------------------------------------------------
Thus only cpu-active-high and cpu-active-low modes are usable.
I think this is wrong.
This patch fixes cpu-active-medium settings for bpi-r3 board.
I know, the patch is not ideal as it can break pwm fan for some users.
Likely this is the only official mt7986-bpi-r3 heatsink+fan solution
available on the market.
This patch may not be enough. Users may wants to tweak their thermal_zone0
trip points, thus tuning fan rotation speed depending on cpu temperature.
That can be done on the base of the following example:
=== example =========
# cpu temperature below 25 Celsius degrees, no rotation
echo 25000 > /sys/class/thermal/thermal_zone0/trip_point_4_temp
# cpu temperature in [25..32] Celsius degrees, normal rotation speed
echo 32000 > /sys/class/thermal/thermal_zone0/trip_point_3_temp
# cpu temperature above 50 Celsius degrees, max rotation speed
echo 50000 > /sys/class/thermal/thermal_zone0/trip_point_2_temp
=====================
Signed-off-by: Mikhail Kshevetskiy <mikhail.kshevetskiy@iopsys.eu>
Acked-by: Frank Wunderlich <frank-w@public-files.de>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
---
Changes from v1 to v2:
* improve patch description
Changes from v2 to v3:
* added question to Frank Wunderlich
Changes from v3 to v4:
* Acked by Frank Wunderlich
---
arch/arm64/boot/dts/mediatek/mt7986a-bananapi-bpi-r3.dts | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/arch/arm64/boot/dts/mediatek/mt7986a-bananapi-bpi-r3.dts
+++ b/arch/arm64/boot/dts/mediatek/mt7986a-bananapi-bpi-r3.dts
@@ -42,7 +42,7 @@
compatible = "pwm-fan";
#cooling-cells = <2>;
/* cooling level (0, 1, 2) - pwm inverted */
- cooling-levels = <255 96 0>;
+ cooling-levels = <255 40 0>;
pwms = <&pwm 0 10000>;
status = "okay";
};