Re: [RFC] Bluetooth: don't use ESCO setup for BT_VOICE

Hi Pauli,

According to user reports, how HCI_Enhanced_Setup_Synchronous_Connection
is currently used to establish MSBC connections results to broken audio
on some adapters (QCA6174, mt7921e).

Revert to previous behavior of using HCI_Setup_Synchronous_Connection,
unless the user has explicitly set BT_CODEC sockopt. Since bt_codec
contents come from Core specification, use a separate flag for the
setting.

Fixes: b2af264ad3af ("Bluetooth: Add support for HCI_Enhanced_Setup_Synchronous_Connection command")
Link: https://bugzilla.kernel.org/show_bug.cgi?id=215576
Signed-off-by: Pauli Virtanen <redacted>
---

Notes:
   Maybe we want to use the ESCO connect setup only when userspace has
   requested the codec offload support.  I don't have any of the broken
   hardware myself, so this is not tested on them.

   Alternatively, there should be some driver quirk to indicate the
   enhanced sco connection setup is not broken.

yes, these needs to be marked as my hardware is broken.

From a specification point of view, the Enhanced Setup Sync Conn is a super set of the Setup Sync Conn (which is a super set of Add SCO). If implementers screwed that up, we clear spell that out.

Maybe we messed up the usage of the Enhanced Setup Sync Conn and that should be of course checked. I hope the hardware manufactures can chime in here. Or provide firmware updates.

Regards

Marcel