Phone disconnects shortly after accepting a call

[Daflyinskwirl]

Everything is stable, audio is playing (separate cracking issues I'm still trying to figure out the solution for in another thread), I get a call. I answer call. Everything is fine for 30 seconds or so. Then, all of a sudden bluetooth will say disconnected, and I can no longer hear the person I'm talking to. The call is still connected however.

Trying to get bluetooth to reconnect doesn't seem to work, it almost always stays disconnected.

It does this fairly often. Is there anyway for me to troubleshoot this problem, or at least report it as a bug?

Hardware:
Pixel 9 pro
Rpi4
5.0 bluetooth dongle
Sabrent USB DAC

Do I not need the external bluetooth adapter? This was a carry-over from my Open Auto Pro days and I reused all the same hardware.

[hudiy]

Could you send the output of the dmesg command after the problem occurs? If the phone cannot connect to the Raspberry Pi afterward, it may indicate a firmware crash or an internal error in its code. The dmesg output should help determine whether something is happening with the Raspberry Pi itself.

[Zyox]

Same issue for me with pixel 8 Pro. Nearly exactly 30s. Reconnecting is then really tricky

Pi 4
Onboard Bluetooth
Hifiberry DAC on carpihatPro

[hudiy]

Same issue for me with pixel 8 Pro. Nearly exactly 30s. Reconnecting is then really tricky

Pi 4
Onboard Bluetooth
Hifiberry DAC on carpihatPro

Could you please also send the output of the dmesg command after the problem occurs?

[hudiy]

Same issue for me with pixel 8 Pro. Nearly exactly 30s. Reconnecting is then really tricky

Pi 4
Onboard Bluetooth
Hifiberry DAC on carpihatPro

Does the issue still occur? We can’t reproduce it on any of our Raspberry Pi 4B units. It might be related to the hardware revision.

If the problem persists, could you test with the built-in Bluetooth module driven by the mini UART instead of PL011?

You can enable this in /boot/firmware/config.txt by adding the overlay, for example under the [all] section:

Code: Select all

[all]
dtoverlay=miniuart-bt

The change requires restarting the Raspberry Pi.

[Zyox]

Could you send the output of the dmesg command after the problem occurs? If the phone cannot connect to the Raspberry Pi afterward, it may indicate a firmware crash or an internal error in its code. The dmesg output should help determine whether something is happening with the Raspberry Pi itself.

2 phone calls attempted now to do this.
Android auto started and played music fine.
On attempted first call Bluetooth instantly disconnected

[Zyox]

Same issue for me with pixel 8 Pro. Nearly exactly 30s. Reconnecting is then really tricky

Pi 4
Onboard Bluetooth
Hifiberry DAC on carpihatPro

Does the issue still occur? We can’t reproduce it on any of our Raspberry Pi 4B units. It might be related to the hardware revision.

If the problem persists, could you test with the built-in Bluetooth module driven by the mini UART instead of PL011?

You can enable this in /boot/firmware/config.txt by adding the overlay, for example under the [all] section:

Code: Select all

[all]
dtoverlay=miniuart-bt

The change requires restarting the Raspberry Pi.

Then doing this seemed to fix the issue for now.

Audio stuttering/cracking/popping remains however. Covering that in the other thread.

[hudiy]

Thanks for the dmesg log.
The line hci0: hardware error 0x00 points to a firmware issue. According to the HCI driver source, 0x0c03 is the opcode for resetting the Bluetooth chip.
If the problem doesn’t appear when using miniuart-bt but only with PL011, it’s most likely a bug somewhere along the driver–DMA–firmware path.

During an HFP/SCO connection, the system performs a lot of very small transfers (for built-in Bluetooth, the MTU is 60 bytes), and it seems this causes the firmware to crash.

Would you be able to take a picture of your Raspberry Pi board? We’ll try to find one with the same markings so we can reproduce the problem and report it on the Pi Foundation GitHub.

[Zyox]

Please let this be the side you need. I really don't want to have to remove the CarPiHat!

[hudiy]

That is enough, thanks. We will try to find the same hardware revision and reproduce the issue so we can provide as much information as possible in a bug report for the Raspberry Pi Foundation.

btw. Are you able to test the audio in version 1.2 on your setup and check how it behaves (regarding crackling/popping)?

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