I checked the source code of quirks-table.h on branch 4.19-rc8. It still contains the problematic workaround. It doesn't seem to fit any longer to the headphones current firmware. Checking the 4.15.7 kernel (without the quirk) works much better. At least the device is shown in the mixer and fixing the samplerate to 48kHz leads to a useful configuration. To be honest I do not really understand how to define a fixed table for supported sample rate without fiddling with other parameters. The HID seems to working too. At least I am able to use the headphone buttons to in/decrease the volume and to stop and restart playback. The microphone is not shown - but that does not seem to work on windows either - as far as I understand the orginal patch to support the headphones.
With the qurik in place I get no really helpful error messages ...
I hope that helps to clarify the situation,
Mutz
Takashi Iwai tiwai@suse.de schrieb am Di., 30. Okt. 2018 um 12:24 Uhr:
On Sun, 28 Oct 2018 22:00:35 +0100, Mutz Heuer wrote:
USB-Audio Connection on Bowers & Wilkens PX Bluetooth Headphones started working when upgrading kernel from 4.13 to 4.15 series. Then it suddenly stopped working again on newer kernels. The bug report has been generated on the latest working mainline kernel 4.15.7. All newer kernels have some usb quirks in place, which should fix the playback sample rates to 48
kHz.
The quirk seems not to be working correctly - it seems to hinder the
audio
system to recognize the USB-device as a sound device.
The Headphones work on kernels before 4,15.7 when manually configuring pulseaudio to a default samplerate of 48 kHz.
PX Headphones are on the newest firmware level.
See https://patchwork.kernel.org/patch/10265345/. Dropping that patch
and
recompiling the kernel leads to a situation where alsa and pulseaudio
seem
to to be working again.
Adding
default-sample-rate = 48000to /etc/pulse/daemon.conf leads to working headphones.
Maybe the patch has to be adjusted to newer firmware? A quirk seems to be really necessary to avoid the specific patch to daemon.conf.
More details can be found in https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1773697 What would be the best way to proceed?
Could you check the latest Linus git tree (or for-linus branch of sound git tree)? The workaround for the buggy firmware was already included there. Let me know if it still doesn't suffice.
thanks,
Takashi