Automatic Switchover between Headphones and Speakers on FreeBSD Laptops with device.hints
Sat Mar 23, 2019 · 446 words

If you’re like me and run FreeBSD on a laptop (mine is a HP EliteBook x360 1030 G2), one issue you may encounter is the fact that switching between speakers and headphones isn’t automatic. This isn’t a HP-specific problem as I also know this impacts Dell laptops, and probably impacts other laptop brands as well.

However, not all hope is lost. FreeBSD allows you to specify your audio device in device.hints to make automatic switchover between the integrated speakers and 3.5mm jack possible.

On laptops where the switchover isn’t automatic, you often have multiple pcm devices. On my EliteBook, these pcm devices exist (via dmesg | grep pcm):

pcm0: <Conexant (0x2008) (Analog)> at nid 23 and 26 on hdaa0
pcm1: <Conexant (0x2008) (Right Analog Headphones)> at nid 22 on hdaa0
pcm2: <Intel Kabylake (HDMI/DP 8ch)> at nid 3 on hdaa1

While I’m no expert on FreeBSD’s audio subsystem or an audio engineer (the best I know about audio is really only a bit more than “Beats by Dr. Dre suck”), from what I understand, hdaaX is the system’s HD “audio codec” (meaning audio chip X) and pcmY is FreeBSD’s audio instance (meaning instance Y of the pcm subsystem).

Here, hdaa0 is the audio codec for the integrated Conexant audio used by the headphones and speakers, and hdaa1 is the audio codec used by HDMI.

The issue which arises is that with one hdaa device, you have two pcm devices for your integrated audio, and FreeBSD doesn’t automatically configure switching between this. To enable this switching, you need one line in /boot/device.hints for your headphones:

hint.hdac.X.cad0.nidYY.config="as=1 seq=15 device=Headphones"

Where X is the number assigned to the hdaa associated with your “Headphones” dmesg line, and YY is the nid number assigned from the same line.

You also need one line in device.hints for your speakers:

hint.hdac.X.cad0.nidZZ.config="as=2 seq=0"

Where X is the number assigned to the hdaa associated with your “Analog” dmesg line, and ZZ is the nid number assigned from the same line.

Keep in mind that your system may use different terms for “Headphones” and “Analog”. Also, if you have multiple nid values, use one. If that doesn’t work, try the other one.

Using the output for my system, my device.hints has the following new lines:

hint.hdac.0.cad0.nid26.config="as=1 seq=15 device=Headphones"
hint.hdac.0.cad0.nid22.config="as=2 seq=0"

Note: Don’t just copy and paste my values, your system may be different!

After entering the following lines, you should now reboot.

Once you rebooted, try playing something with audio (e.g. YouTube) with and without headphones plugged in. This should work, as it works for me with the HP EliteBook x360 1030 G2 running FreeBSD 12.0 mentioned above along with AKG Y50BT headphones in wired mode.


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