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