[Qualcomm Atheros QCA6174] Bluetooth audio choppiness

3b:00.0 Network controller: Qualcomm Atheros QCA6174 802.11ac Wireless Network Adapter (rev 32)
 Subsystem: Bigfoot Networks, Inc. QCA6174 802.11ac Wireless Network Adapter
 Control: I/O- Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR- FastB2B- DisINTx+
 Status: Cap+ 66MHz- UDF- FastB2B- ParErr- DEVSEL=fast >TAbort- <TAbort- <MAbort- >SERR- <PERR- INTx-
 Latency: 0, Cache Line Size: 64 bytes
 Interrupt: pin A routed to IRQ 138
 Region 0: Memory at ed200000 (64-bit, non-prefetchable) [size=2M]
 Capabilities: [40] Power Management version 3
  Flags: PMEClk- DSI- D1- D2- AuxCurrent=375mA PME(D0+,D1-,D2-,D3hot+,D3cold+)
  Status: D0 NoSoftRst- PME-Enable- DSel=0 DScale=0 PME-
 Capabilities: [50] MSI: Enable+ Count=1/8 Maskable+ 64bit-
  Address: fee00498 Data: 0000
  Masking: 000000fe Pending: 00000000
 Capabilities: [70] Express (v2) Endpoint, MSI 00
  DevCap: MaxPayload 256 bytes, PhantFunc 0, Latency L0s unlimited, L1 <64us
   ExtTag- AttnBtn- AttnInd- PwrInd- RBE+ FLReset- SlotPowerLimit 10.000W
  DevCtl: Report errors: Correctable- Non-Fatal- Fatal- Unsupported-
   RlxdOrd+ ExtTag- PhantFunc- AuxPwr- NoSnoop-
   MaxPayload 256 bytes, MaxReadReq 512 bytes
  DevSta: CorrErr+ UncorrErr- FatalErr- UnsuppReq+ AuxPwr+ TransPend-
  LnkCap: Port #0, Speed 2.5GT/s, Width x1, ASPM L0s L1, Exit Latency L0s <4us, L1 <64us
   ClockPM+ Surprise- LLActRep- BwNot- ASPMOptComp+
  LnkCtl: ASPM L1 Enabled; RCB 64 bytes Disabled- CommClk+
   ExtSynch- ClockPM+ AutWidDis- BWInt- AutBWInt-
  LnkSta: Speed 2.5GT/s, Width x1, TrErr- Train- SlotClk+ DLActive- BWMgmt- ABWMgmt-
  DevCap2: Completion Timeout: Not Supported, TimeoutDis+, LTR+, OBFF Via message
  DevCtl2: Completion Timeout: 50us to 50ms, TimeoutDis-, LTR+, OBFF Disabled
  LnkCtl2: Target Link Speed: 2.5GT/s, EnterCompliance- SpeedDis-
    Transmit Margin: Normal Operating Range, EnterModifiedCompliance- ComplianceSOS-
    Compliance De-emphasis: -6dB
  LnkSta2: Current De-emphasis Level: -6dB, EqualizationComplete-, EqualizationPhase1-
    EqualizationPhase2-, EqualizationPhase3-, LinkEqualizationRequest-
 Capabilities: [100 v2] Advanced Error Reporting
  UESta: DLP- SDES- TLP- FCP- CmpltTO- CmpltAbrt- UnxCmplt- RxOF- MalfTLP- ECRC- UnsupReq- ACSViol-
  UEMsk: DLP- SDES- TLP- FCP- CmpltTO- CmpltAbrt- UnxCmplt- RxOF- MalfTLP- ECRC- UnsupReq- ACSViol-
  UESvrt: DLP+ SDES+ TLP- FCP+ CmpltTO- CmpltAbrt- UnxCmplt- RxOF+ MalfTLP+ ECRC- UnsupReq- ACSViol-
  CESta: RxErr+ BadTLP- BadDLLP+ Rollover- Timeout+ NonFatalErr-
  CEMsk: RxErr- BadTLP- BadDLLP- Rollover- Timeout- NonFatalErr+
  AERCap: First Error Pointer: 00, GenCap- CGenEn- ChkCap- ChkEn-
 Capabilities: [148 v1] Virtual Channel
  Caps: LPEVC=0 RefClk=100ns PATEntryBits=1
  Arb: Fixed- WRR32- WRR64- WRR128-
  Ctrl: ArbSelect=Fixed
  Status: InProgress-
  VC0: Caps: PATOffset=00 MaxTimeSlots=1 RejSnoopTrans-
   Arb: Fixed- WRR32- WRR64- WRR128- TWRR128- WRR256-
   Ctrl: Enable+ ID=0 ArbSelect=Fixed TC/VC=ff
   Status: NegoPending- InProgress-
 Capabilities: [168 v1] Device Serial Number 00-00-00-00-00-00-00-00
 Capabilities: [178 v1] Latency Tolerance Reporting
  Max snoop latency: 3145728ns
  Max no snoop latency: 3145728ns
 Cap...

This bug is missing log files that will aid in diagnosing the problem. While running an Ubuntu kernel (not a mainline or third-party kernel) please enter the following command in a terminal window:

apport-collect 1810636

and then change the status of the bug to 'Confirmed'.

If, due to the nature of the issue you have encountered, you are unable to run this command, please add a comment stating that fact and change the bug status to 'Confirmed'.

This change has been made by an automated script, maintained by the Ubuntu Kernel Team.

apport information

apport information

apport information

apport information

apport information

apport information

apport information

apport information

apport information

apport information

apport information

apport information

apport information

apport information

Does firmware in [1] help?

[1] https://github.com/kvalo/ath10k-firmware

@kaihengfeng I did try the latest version of the QCA6174 4.4.1 firmware which matches the firmware in linux-firmware v176, and the result is the same. I replaced firmware-6 file in the /lib/firmware/ath10k/QCA6174/hw3.0 folder to test this.

[1] https://github.com/kvalo/ath10k-firmware/blob/master/QCA6174/hw3.0/4.4.1/firmware-6.bin_WLAN.RM.4.4.1-00128-QCARMSWPZ-1

board-2.bin is also required.

@kaihengfeng - after adding board-2.bin, neither the wireless or bluetooth is loading. I've ensured I downloaded the files correctly and used the same file permissions.

berg@bxps:$ md5sum ~/Downloads/firmware-6.bin_WLAN.RM.4.4.1-00128-QCARMSWPZ-1 /lib/firmware/ath10k/QCA6174/hw3.0/firmware-6.bin
32c3af49730a0babdb1f3004219debf5 /home/berg/Downloads/firmware-6.bin_WLAN.RM.4.4.1-00128-QCARMSWPZ-1
32c3af49730a0babdb1f3004219debf5 /lib/firmware/ath10k/QCA6174/hw3.0/firmware-6.bin
berg@bxps:$ md5sum ~/Downloads/board-2.bin /lib/firmware/ath10k/QCA6174/hw3.0/board-2.bin
db8264c352f202f38dfb99175209274c /home/berg/Downloads/board-2.bin
db8264c352f202f38dfb99175209274c /lib/firmware/ath10k/QCA6174/hw3.0/board-2.bin

I'll post my syslog from the boot, but I can't see any references for the PCI id of the chip or the kernel driver.

@kaihengfeng - do I need to do an update-initramfs -u -v -k all and then shutdown completely after placing the files?

No, ath10k_pci is not included in the initramfs so replace firmware alone is sufficient.

Ok, I managed to get the latest firmware working. It still exhibits the same issue. I think I must of only rebooted last time instead of shutting down completely.

I've tried the speaker sitting on top of the track-pad, about 50 cm away from the laptop - all to the same effect - the it's like it misses an audio packet, and rather than dropping the packet, it re-transmits again, buffering all subsequent packets for the stream. I would rather lose the packets completely in this case.

The speaker is a Sony SRS-HG1. I can pair the speaker to my Xiaomi Mi8 phone and it negotiates LDAC codec for the Bluetooth audio sink. I can then run high load on the Mi8 WiFi and play a movie in FullHD over DLNA and it never skips a beat, there is a small delay as you'd expect with Bluetooth, but it's less than 100 ms and seems normal after a short while.

I experienced this problem also in another location when I was house sitting recently - so different environment/access points etc. I think demonstrating the problem with the speaker and my phone without any problems puts me back on the firmware/driver troubleshooting path.

Do you have any other ideas @kaihengfeng? Would you like me to do Bluetooth packet capture?

Here is a demo of the stuttering sound, you can hear it at around 11 seconds after I start a file copy over SMB.

pulseaudio 1:12.2-0ubuntu4

Firmware seems less stable than that in linux-firmware 1.176. Getting strange delays with the WiFi in general.

One thing I noticed was that it was better, but not perfect on my 2.4 GHz SSID/radio. During this time my throughput from my server is only about 2 MB/s. When I switch to 5 GHz SSID/radio, the throuhgput increases to around 20 MB/s.

To clarify, higher bandwidth transfers on the radio seems to increase the stuttering, delay.

Here is my tlp config, incase there's anything in there you think could be related to my issues because of power saving etc.

Subscribed ath10k maintainer. I think he uses Launchpad, but if he doesn't reply here, please raise this issue to <email address hidden>.

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

It might be worth saying, however, without the pulseaudio-modules-bt in [2] in comment #27, the throughput of the WLAN was not affected when playing sound via the A2DP sync and I was seeing abotu 18 MB/s. Maybe I'm a bit premature in saying it's solely a pulseaudio-modules-bt issue. Regardless, it seems to be working a lot better with LDAC.

I'm happy this is pretty much solve. With the pulseaudio-modules-bt from comment 27 [2], I've experienced far less audio lag overall. Every now and again I get a small glitch that delays it 10ms or so, but it's so much better now I'm happy to close this and mark it as non-issue.

Status changed to 'Confirmed' because the bug affects multiple users.