Cannot send bluetooth SCO packets with Raspberry Pi 3 internal bluetooth module.

[Nikolay]

I tried to open SCO socket to bluetooth headset and send audio to the headset. Regardless I successfully write in socket, there is no sound in the headset. And there is no outgoing packages in 'hcidump -X' output.

hciconfig output after some attempts to read/write:
$ hciconfig
hci0: Type: BR/EDR Bus: UART
 BD Address: B8:27:EB:EF:57:6F ACL MTU: 1021:8 SCO MTU: 64:1
 UP RUNNING
 RX bytes:32155 acl:487 sco:0 events:740 errors:0
 TX bytes:11882107 acl:392 sco:228259 commands:225 errors:0

RX sco counter is zero.

Capture audio from headset works fine.
External USB dongle(CSR 4.0) works fine with the same board, OS and headset.

This issue quite familiar with this one - https://bugs.launchpad.net/snappy/+bug/1679432 but here I can read data.

[Zygmunt Krynicki (zyga)]

This seems like an issue with the kernel or with a specific snap (bluez), not snapd. I'm closing this bug as invalid but please feel free to re-open it and re-assign to another project as appropriate.