Bug 216382

Summary: [bisected][regression] mediatek bluetooth 13d3:3563 (mt7921e) doesn't work with audio devices.
Product: Drivers Reporter: Arek Ruśniak (arek.rusi)
Component: BluetoothAssignee: linux-bluetooth (linux-bluetooth)
Status: RESOLVED CODE_FIX    
Severity: normal CC: luiz.dentz
Priority: P1    
Hardware: All   
OS: Linux   
Kernel Version: 6.0-rc1 Subsystem:
Regression: No Bisected commit-id:
Attachments: btmon -w log # 6.0-rc1
btmon -w log # 5.19x
Patch

Description Arek Ruśniak 2022-08-19 16:15:30 UTC 
After update to new 6.0rc1 I can't use any bt-earphones.  
I've checked in bluetoothctl: devices are still connected but none of endpoint/transport entries are creates.

XB1S gamepad works without any issues.

bisecting result:
---
26afbd826ee326e63a334c37fd45e82e50a615ec is the first bad commit
commit 26afbd826ee326e63a334c37fd45e82e50a615ec
Author: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>
Date:   Mon Jul 29 18:15:43 2019 +0300

    Bluetooth: Add initial implementation of CIS connections
    
    This adds the initial implementation of CIS connections and introduces
    the ISO packets/links.
---

can't revert this commit. 

*Aditionally, I've tried this kernel on second machine with AX210 wifi/bt combo and issue doesn't appear. So I assume problem is limited to mediatek module.
Comment 1 Luiz Von Dentz 2022-08-19 18:39:01 UTC 
I suspect this could be due some HCI command during initialization, could you please collect the HCI using btmon?
Comment 2 Arek Ruśniak 2022-08-19 20:12:44 UTC 
Created attachment 301608 [details]
btmon -w log # 6.0-rc1

Hi,
this is log for rc1, hope it's not a big problem.
Comment 3 Arek Ruśniak 2022-08-19 20:19:57 UTC 
Created attachment 301609 [details]
btmon -w log # 5.19x

this is log for connected/worked device.
Comment 4 Luiz Von Dentz 2022-09-02 00:29:43 UTC 
Created attachment 301727 [details]
Patch

This shall fix the problem, weird that CI didn't find it though since it quite clear that ACL buffers will not be initialized thus preventing any ACL traffic.
Comment 5 Arek Ruśniak 2022-09-02 19:06:02 UTC 
thanks Luiz for fix this, i've tested it on top rc3 & master and my headphones live again.
Comment 6 Arek Ruśniak 2022-09-13 18:11:53 UTC 
fixed in rc5