Hello!
On 7/16/20 4:14 PM, Marcel Holtmann wrote:
>> The MediaTek Bluetooth platform (MT6630 etc.) has a peculiar implementation
>> for the eSCO/SCO connection via BT/EDR: the host controller returns error
>> code 0x20 (LMP feature not supported) for HCI_Setup_Synchronous_Connection
>> (0x0028) command without actually trying to setup connection with a remote
>> device in case such device (like Digma BT-14 headset) didn't advertise its
>> supported features. Even though this doesn't break compatibility with the
>> Bluetooth standard it breaks the compatibility with the Hands-Free Profile
>> (HFP).
>>
>> This patch returns the compatibility with the HFP profile and actually
>> tries to check all available connection parameters despite of the specific
>> MediaTek implementation. Without it one was unable to establish eSCO/SCO
>> connection with some headsets.
>
> please include the parts of btmon output that show this issue.
Funny, I had removed that part from the original patch. Here's that log:
< HCI Command: Setup Synchronous Connection (0x01|0x0028) plen 17
#1 [hci0] 6.705320
Handle: 50
Transmit bandwidth: 8000
Receive bandwidth: 8000
Max latency: 10
Setting: 0x0060
Input Coding: Linear
Input Data Format: 2's complement
Input Sample Size: 16-bit
of bits padding at MSB: 0
Air Coding Format: CVSD
Retransmission effort: Optimize for power consumption (0x01)
Packet type: 0x0380
3-EV3 may not be used
2-EV5 may not be used
3-EV5 may not be used
> HCI Event: Command Status (0x0f) plen 4
> #2 [hci0] 6.719598
Setup Synchronous Connection (0x01|0x0028) ncmd 1
Status: Unsupported LMP Parameter Value / Unsupported LL Parameter
Value (0x20)
>> Based on the patch by Ildar Kamaletdinov <[email protected]>.
>>
>> Signed-off-by: Sergey Shtylyov <[email protected]>
>>
>> ---
>> This patch is against the 'bluetooth-next.git' repo.
>>
>> net/bluetooth/hci_event.c | 8 ++++++++
>> 1 file changed, 8 insertions(+)
>>
>> Index: bluetooth-next/net/bluetooth/hci_event.c
>> ===================================================================
>> --- bluetooth-next.orig/net/bluetooth/hci_event.c
>> +++ bluetooth-next/net/bluetooth/hci_event.c
>> @@ -2187,6 +2187,13 @@ static void hci_cs_setup_sync_conn(struc
>> if (acl) {
>> sco = acl->link;
>> if (sco) {
>> + if (status == 0x20 && /* Unsupported LMP Parameter
>> value */
>> + sco->out) {
>> + sco->pkt_type = (hdev->esco_type &
>> SCO_ESCO_MASK) |
>> + (hdev->esco_type &
>> EDR_ESCO_MASK);
>> + if (hci_setup_sync(sco, sco->link->handle))
>> + goto unlock;
>> + }
>> sco->state = BT_CLOSED;
>
> since this is the command status event, I doubt that sco->out check is needed.
Can't comment oin this, my BT fu is too weak...
> And I would start with a switch statement right away.
Funny, I had removed the *switch* statement from the original patch... :-)
> I also think that we need to re-structure this hci_cs_setup_sync_conn
> function a little to avoid the deep indentation.
> Make it look more like hci_sync_conn_complete_evt also use a switch statement
> even if right now we only have one
> entry.
Indeed, done now. :-)
> Regards
>
> Marcel
MBR, Sergey
