Ok, I'm pretty sure this is a pulseaudio issue now and I'm going to
close.
I reverted back to linux-firmware 1.176, and I had also used undervolt
[1] to help reduce thermal load on the Core i9 Dell XPS 15 which has
suffered from thermal shutdown under high load. I disabled undervolt
service from running and ensured everything was back to normal values -
the stuttering improved, but was still present.
I then focused on the difference between my Mi8 and my Ubuntu 18.10
installation. The Mi8 is running a LinesageOS ROM that supports
LDAC/Apt-X codecs. I noticed with the regular AD2P codec in Ubuntu that
I was getting some noise included in the Bluetooth audio encoding, and
it sounded much cleaner via the Mi8 connection. I then found pulseaudio-
modules-bt repo on github [2] that includes [3] a Ubuntu 18.04|18.10
repo that enabled LDAC/Apt-X codecs, LDAC is supported by the Sony
bluetooth speaker.
After installing and rebooting the machine, I confirmed that the codec
was correctly initialised in the a2dp sync:
berg@bxps:~$ pactl list sinks | grep -e bluez -e a2dp_codec
Name: bluez_sink.E0_37_BF_09_F9_8B.a2dp_sink
Driver: module-bluez5-device.c
Monitor Source: bluez_sink.E0_37_BF_09_F9_8B.a2dp_sink.monitor
bluetooth.a2dp_codec = "LDAC"
device.api = "bluez"
bluez.path = "/org/bluez/hci0/dev_E0_37_BF_09_F9_8B"
bluez.class = "0x240414"
bluez.alias = "bshg"
The sound is now perfect, and copying files across the network results
in no stuttering. I think this proves that the btcoex support is working
correctly and there is no issue specifically with the Qualcomm firmware.
I notice if I pair the bluetooth speaker and play back audio my network
throughput is limited to about 14-15 MB/s, when I turn of the speaker it
improves to 17-18 MB/s. So the module is correctly allowing bluetooth to
operate with priority.
Resuming the undervolt [1] service, I notice no stuttering as well with
the updated pulseaudio and pulseaudio-module-bt packages in [2].
I'm going to continue testing for a few days before closing this bug,
but I'm pretty sure I've gotten to the bottom of this one. Thanks
@kaihenfeng.
[1] https://github.com/georgewhewell/undervolt
[2] https://github.com/EHfive/pulseaudio-modules-bt
[3] https://github.com/EHfive/pulseaudio-modules-bt/wiki/Packages
** Summary changed:
- QCA6174 doesn't utilise btcoex - Ubuntu 18 Bluetooth Audio
Skip/Stutter/Delay WiFi bandwidth conflict Dell XPS 9570
+ Suspect QCA6174 btcoex | Ubuntu 18 Bluetooth Audio Skip/Stutter/Delay WiFi
bandwidth conflict Dell XPS 9570 [Pending PulseAudio testing]
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https://bugs.launchpad.net/bugs/1810636
Title:
Suspect QCA6174 btcoex | Ubuntu 18 Bluetooth Audio Skip/Stutter/Delay
WiFi bandwidth conflict Dell XPS 9570 [Pending PulseAudio testing]
Status in linux package in Ubuntu:
Confirmed
Bug description:
I'm running Linux 4.20.0-042000-generic #201812232030 x64 on a Dell XPS 9570
with QCA6174 chipset, and have had the problem with Bluetooth audio choppiness
ever since I have owned this laptop. This problem has persisted for me with
previous kernels. If I disable wifi and use media on machine
locally, the problem doesn't occur.
Note: I've reverted back v4.18.0-13-generic and reproduced the problem for
the apport-collect report.
It started with Ubuntu 18.04 and continues with 18.10. It's
particularly noticeable when the when saturating the WLAN connection
with throughput, i.e. copying a large file sequentially across from a
samba share, but also streaming video online results in the audio
progressively delaying over-time. Re-establishing the Bluetooth audio
sync restores the sync, but slowly creeps out again.
I've upgraded my linux-firmware package to disco 176 to match v4.20
kernel drivers ref: https://launchpad.net/ubuntu/+source/linux-
firmware/1.176
The ath10k_core driver that supports this device has a reference for
btcoex: ref
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/net/wireless/ath/ath10k/core.c?h=v4.20#n2598
It's possible that the Bluetooth component firmware is not supporting
or communicating btcoex compatibility, but this is starting to reach
the edge of my ability to diagnose the problem.
This btcoex support in ath9k has resolved/improved the Bluetooth
bandwidth problem for older Qualcomm chipsets as shown in
https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1746164
As a troubleshooting step, I've also tried the very latest firmware-6 file
from, but I'm continuing to experience the problem ref:
https://github.com/kvalo/ath10k-firmware/tree/master/QCA6174/hw3.0/4.4.1
---
ProblemType: Bug
ApportVersion: 2.20.10-0ubuntu13.1
Architecture: amd64
AudioDevicesInUse:
USER PID ACCESS COMMAND
/dev/snd/controlC0: berg 2871 F.... pulseaudio
CurrentDesktop: GNOME
DistroRelease: Ubuntu 18.10
InstallationDate: Installed on 2018-07-02 (187 days ago)
InstallationMedia: Ubuntu 18.04 LTS "Bionic Beaver" - Release amd64 (20180426)
MachineType: Dell Inc. XPS 15 9570
Package: linux (not installed)
ProcEnviron:
TERM=xterm-256color
PATH=(custom, no user)
XDG_RUNTIME_DIR=<set>
LANG=en_AU.UTF-8
SHELL=/bin/bash
ProcFB: 0 inteldrmfb
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-4.18.0-13-generic
root=UUID=c825a7b0-a5ac-41de-bd57-7663fef8a1f1 ro quiet splash vt.handoff=1
ProcVersionSignature: Ubuntu 4.18.0-13.14-generic 4.18.17
RelatedPackageVersions:
linux-restricted-modules-4.18.0-13-generic N/A
linux-backports-modules-4.18.0-13-generic N/A
linux-firmware 1.176
Tags: cosmic
Uname: Linux 4.18.0-13-generic x86_64
UpgradeStatus: Upgraded to cosmic on 2018-10-18 (79 days ago)
UserGroups: adm cdrom dip libvirt lpadmin plugdev sambashare sudo
_MarkForUpload: True
dmi.bios.date: 11/02/2018
dmi.bios.vendor: Dell Inc.
dmi.bios.version: 1.6.0
dmi.board.name: 07GHH0
dmi.board.vendor: Dell Inc.
dmi.board.version: A00
dmi.chassis.type: 10
dmi.chassis.vendor: Dell Inc.
dmi.modalias:
dmi:bvnDellInc.:bvr1.6.0:bd11/02/2018:svnDellInc.:pnXPS159570:pvr:rvnDellInc.:rn07GHH0:rvrA00:cvnDellInc.:ct10:cvr:
dmi.product.family: XPS
dmi.product.name: XPS 15 9570
dmi.product.sku: 087C
dmi.sys.vendor: Dell Inc.
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