Re: [PATCH RESEND v4] arm64: dts: mediatek: mt7986-bpi-r3: Change fan PWM value for mid speed

[AngeloGioacchino Del Regno]

Il 09/10/25 10:55, Mikhail Kshevetskiy ha scritto:
> Is there any chances get it merged to linux-6.18?

No, the window is closed - but I have added this patch to my notes, will be picked
as soon as RC1 is out, will be in linux-next soon after, and will land in 6.19.

Cheers,
Angelo

> Regards,
> Mikhail Kshevetskiy
>
>
>
> On 30.09.2025 14:34, AngeloGioacchino Del Regno wrote:
> > Il 30/09/25 04:16, Mikhail Kshevetskiy ha scritto:
> > > 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@xxxxxxxxx>
> > > Acked-by: Frank Wunderlich <frank-w@xxxxxxxxxxxxxxx>
> >
> > Reviewed-by: AngeloGioacchino Del Regno
> > <angelogioacchino.delregno@xxxxxxxxxxxxx>