[Bug 201539] AMDGPU R9 390 automatic fan speed control in Linux 4.19/4.20/5.0

bugzilla-daemon at bugzilla.kernel.org bugzilla-daemon at bugzilla.kernel.org
Mon Jun 24 02:18:44 UTC 2019


https://bugzilla.kernel.org/show_bug.cgi?id=201539

--- Comment #19 from Sean Birkholz (supasean at hotmail.com) ---
I've done a bit of digging and I've managed to get a proper hysteresis value to
appear in a 5.1.14 kernel built from source.

I now have this output from sensors:

amdgpu-pci-0100
Adapter: PCI adapter
vddgfx:       +1.00 V  
fan1:             N/A  (min =    0 RPM, max =    0 RPM)
temp1:        +66.0°C  (crit = +104000.0°C, hyst = +90.0°C)
power1:       29.02 W  (cap = 208.00 W)

I don't know why proper values are not set automatically because I've found the
correct values in tons of source files but none of the #defines appear to be
used?  And much of the source doesn't appear to differ between 5.1.14 and
4.18.x

I modified (kernel src)/drivers/gpu/drm/amd/powerplay/inc/pp_thermal.h and
changed the values of -273150 to 90000.  This corrects the hysteresis value but
I'm still searching for where the critical temp value is actually set.

I *think* fixing these values may fix the fan problem because why would a fan
spin up if its nowhere near the critical or hysteresis values?  No need. 
Except when the critical value is 19x the temp of the sun, the card gets so hot
it protects itself by maxing the fans for a short burst.  That is my theory
anyway, hope to be able to test it soon but no promises.

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