Comment # 7 on bug 1175312 from Giovanni Gherdovich

(In reply to Takashi Iwai from comment #6)
> Thanks.  I misread the error message: it complaints about the sample
> "format", not about sample rate.  And the proc file shows that the device
> supports only S24_3LE format, i.e. 24bit packed in 3 bytes, and it doesn't
> support 16bit format speaker-test program expects, so it was correct
> behavior.  (FWIW, S24_3LE format would work if you run speaker-test without
> -t wav option.)

Ok.

> Then the problem is likely in PulseAudio side.  Could you try to remove once
> UCM profile for the dock?  Remove /usr/share/alsa/ucm/Dell-WD15-Dock
> directory and restart PulseAudio after that.

It works! Thank you.

But that's confusing; how can the Use Case Management profile specific to this
dock prevent it from working?