Hello,
I am a Bluetooth Engineer at Google investigating an interoperability bug between an Android device and AirPods 4. When requesting an L2CAP connection (with PSM = AVDTP) to the AirPods during SDP service discovery, The AirPods L2CAP layer incorrectly responds with a "refused - no resources available" status followed by a Pending status and a Success status. This violates the specification, which says that the request has been fully rejected after the refused status and should not receive followup responses. I suspect the "no resources available" response is a bug. This prevents A2DP from working with the AirPods.
This bug does not exist with AirPods 2 firmware.
Here is a packet capture:
1602 1969-12-31 16:07:04.805261 0.062473 localhost () Apple_6b:db:09 (AirPods) L2CAP 17 Sent Connection Request (AVDTP, SCID: 0x22c6)
1603 1969-12-31 16:07:04.810953 0.005692 controller host HCI_EVT 8 Rcvd Number of Completed Packets
1604 1969-12-31 16:07:04.811078 0.000125 Apple_6b:db:09 (AirPods) localhost () SDP 27 Rcvd Service Search Attribute Request : Device Information: [Bluetooth Profile Descriptor List 0x0009]
1605 1969-12-31 16:07:04.821249 0.010171 localhost () Apple_6b:db:09 (AirPods) SDP 19 Sent Service Search Attribute Response
1606 1969-12-31 16:07:04.876396 0.055147 controller host HCI_EVT 8 Rcvd Number of Completed Packets
1607 1969-12-31 16:07:04.876464 0.000068 Apple_6b:db:09 (AirPods) localhost () L2CAP 21 Rcvd Connection Response - Refused - no resources available (SCID: 0x22c6)
1608 1969-12-31 16:07:04.942539 0.066075 Apple_6b:db:09 (AirPods) localhost () SDP 41 Rcvd Service Search Attribute Request : Unknown: [Bluetooth Profile Descriptor List 0x0009]
1609 1969-12-31 16:07:04.951052 0.008513 localhost () Apple_6b:db:09 (AirPods) SDP 19 Sent Service Search Attribute Response
1610 1969-12-31 16:07:05.010605 0.059553 controller host HCI_EVT 8 Rcvd Number of Completed Packets
1611 1969-12-31 16:07:05.080593 0.069988 Apple_6b:db:09 (AirPods) localhost () SDP 27 Rcvd Service Search Attribute Request : GATT: [Bluetooth Profile Descriptor List 0x0009]
1612 1969-12-31 16:07:05.087636 0.007043 localhost () Apple_6b:db:09 (AirPods) SDP 19 Sent Service Search Attribute Response
1613 1969-12-31 16:07:05.209417 0.121781 controller host HCI_EVT 8 Rcvd Number of Completed Packets
1614 1969-12-31 16:07:05.279491 0.070074 Apple_6b:db:09 (AirPods) localhost () L2CAP 21 Rcvd Connection Response - Pending (SCID: 0x22c6)
1615 1969-12-31 16:07:05.280731 0.001240 Apple_6b:db:09 (AirPods) localhost () L2CAP 21 Rcvd Connection Response - Success (SCID: 0x22c6, DCID: 0x0406)
Please file this bug with the AirPods Bluetooth team.
It would be more appropriate if you filed this bug yourself, as the team might need further logs or details about the Android device, and they would be able to contact you directly with further questions.
Please use https://feedbackassistant.apple.com/ to file a bug report, include all logs, airtraces, and any information you think is relevant.
Once you have filed it, please share the Feedback ID here, and @mention me in your reply, so I can route the bug report to the appropriate team.
Argun Tekant / WWDR Engineering / Core Technologies
