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Differential D54437

asmc: add per-fan manual mode control via sysctl
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Authored by guest-seuros on Wed, Dec 31, 3:11 PM.
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markj
imp
adrian
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rG1ecac45cfc5f: asmc: add per-fan manual mode control via sysctl
Summary

Add per-fan manual mode control via dev.asmc.0.fan.N.manual sysctl.

Apple SMCs support manual fan control via the FS! SMC key,
a 16-bit bitmask where each bit controls one fan (0=auto, 1=manual).

This change adds a new sysctl per fan:

dev.asmc.0.fan.N.manual (0=auto, 1=manual)

When set to manual mode (1), the fan runs at the speed set via

dev.asmc.0.fan.N.targetspeed instead of automatic thermal control.

When set to auto mode (0), the SMC controls fan speed automatically.

The FS! key was already defined in asmcvar.h but not accessible.
This exposes it for debugging, testing, and advanced fan control.

Implementation uses read-modify-write to allow independent control of each fan without affecting others.

Test Plan

Tested on Mac Mini 5,1 and MacBook Pro 11,5 (FreeBSD 16.0-CURRENT):

  1. Check initial state (auto mode): sysctl dev.asmc.0.fan.0.manual Expected: 0 (auto)
  2. Check current fan speed: sysctl dev.asmc.0.fan.0.speed dev.asmc.0.fan.0.targetspeed Note initial values (e.g., 1800 RPM)
  3. Enable manual mode: sudo sysctl dev.asmc.0.fan.0.manual=1 Expected: Returns 1, no errors
  4. Set custom fan speed: sudo sysctl dev.asmc.0.fan.0.targetspeed=3000 Wait 5-10 seconds, check actual speed: sysctl dev.asmc.0.fan.0.speed Expected: Fan speed ramps to ~3000 RPM, audible increase
  5. Return to auto mode: sudo sysctl dev.asmc.0.fan.0.manual=0 Expected: Fan returns to automatic control, speed decreases
  6. Test invalid input: sudo sysctl dev.asmc.0.fan.0.manual=2 Expected: Error (EINVAL), value did not chang
  7. Multi-fan systems (MacBook Pro): Verify fan.1.manual controls second fan independently

Diff Detail

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rG FreeBSD src repository
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Event Timeline

guest-seuros requested review of this revision.Wed, Dec 31, 3:11 PM
guest-seuros created this revision.
markj accepted this revision.Wed, Dec 31, 4:34 PM

Looks ok to me.

sys/dev/asmc/asmc.c
1377

Extra newline here.

This revision is now accepted and ready to land.Wed, Dec 31, 4:34 PM
guest-seuros updated this revision to Diff 168807.Wed, Dec 31, 4:55 PM
This revision now requires review to proceed.Wed, Dec 31, 4:55 PM
guest-seuros marked an inline comment as done.Fri, Jan 2, 4:18 PM
guest-seuros added inline comments.
sys/dev/asmc/asmc.c
1377

Done, but the review got invalidated.

adrian accepted this revision.Fri, Jan 2, 7:13 PM
This revision is now accepted and ready to land.Fri, Jan 2, 7:13 PM
markj added a comment.Mon, Jan 5, 2:23 PM

@adrian would you like to land these asmc patches? I can handle it otherwise.

Closed by commit rG1ecac45cfc5f: asmc: add per-fan manual mode control via sysctl (authored by guest-seuros, committed by markj). · Explain WhyMon, Jan 5, 6:26 PM
This revision was automatically updated to reflect the committed changes.
markj added a commit: rG1ecac45cfc5f: asmc: add per-fan manual mode control via sysctl.
ngie added a subscriber: ngie.Thu, Jan 8, 2:57 AM
ngie added inline comments.
sys/dev/asmc/asmc.c
664

@guest-seuros : is there a reason why CTLFLAG_NEEDGIANT is needed here, or is this mostly a copy-paste of prior OIDs?

markj added inline comments.Thu, Jan 8, 3:02 PM
sys/dev/asmc/asmc.c
664

It's pretty clearly just copied from existing sysctls.

guest-seuros marked an inline comment as done.Thu, Jan 8, 7:53 PM
guest-seuros added inline comments.
sys/dev/asmc/asmc.c
664

Yes! it copied from the prior OID in L657.

I kept the same structure because when previously when i was omitting something, i get kernel panics.

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sys/
dev/
asmc/
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Diff 169085

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sys/dev/asmc/asmc.c

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