While attempting to setup a Motorola S9 headset with a BCM2045-based USB
dongle (Dell-branded Logitech device), I've observed some strange eSCO
behavior. I'm running 64-bit 2.6.31 kernel with bluez 4.52.
Behavior # 1: when attempting a SCO connection, frequently the
connection is rejected with Reserved Slot Violation status return from
the Synchronous Connect Complete event. The SCO connection occasionally
succeeds as an eSCO connection in CVSD mode. I've been experimenting
with this for a while. (After some more observation, it may be that the
successful path is preceded by a mode change to sniff mode) Any ideas?
Behavior # 2: The bt receiver's LM crashes when the eSCO connection is
disconnected (here's the hcidump):
2009-09-15 18:35:41.675877 > SCO data: handle 6 flags 0x00 dlen 48
0000: 29 00 4f 00 46 00 0a 00 00 00 0b 00 1f 00 10 00 ).O.F...........
0010: e8 ff ee ff eb ff bf ff da ff 1e 00 fd ff f1 ff ................
0020: 00 00 ee ff 2b 00 26 00 c8 ff bf ff e4 ff 0b 00 ....+.&.........
2009-09-15 18:35:41.676957 < HCI Command: Disconnect (0x01|0x0006) plen 3
handle 6 reason 0x13
Reason: Remote User Terminated Connection
2009-09-15 18:35:41.681877 > HCI Event: Command Status (0x0f) plen 4
Disconnect (0x01|0x0006) status 0x00 ncmd 1
2009-09-15 18:35:41.685875 > SCO data: handle 6 flags 0x00 dlen 48
0000: 38 00 2d 00 ef ff fd ff 01 00 05 00 29 00 29 00 8.-.........).).
0010: cd ff b1 ff ce ff c9 ff f9 ff 09 00 dd ff 15 00 ................
0020: 02 00 0c 00 49 00 15 00 fc ff e6 ff f7 ff 34 00 ....I.........4.
2009-09-15 18:35:41.685876 > SCO data: handle 6 flags 0x00 dlen 48
0000: 20 00 17 00 27 00 fe ff e5 ff eb ff 0c 00 23 00 ...'.........#.
0010: e7 ff a4 ff c8 ff f6 ff f7 ff fa ff 0e 00 06 00 ................
0020: 10 00 46 00 29 00 d5 ff c4 ff ec ff f4 ff 11 00 ..F.)...........
2009-09-15 18:35:41.685876 > SCO data: handle 6 flags 0x00 dlen 48
0000: 3b 00 20 00 09 00 14 00 ec ff c5 ff f1 ff 26 00 ;. ...........&.
0010: 1e 00 03 00 cf ff b5 ff f5 ff 0d 00 fb ff 0b 00 ................
0020: e2 ff d6 ff 16 00 1d 00 06 00 0f 00 2f 00 40 00 ............/.@.
2009-09-15 18:35:41.695877 > SCO data: handle 6 flags 0x00 dlen 48
0000: 1a 00 eb ff eb ff f0 ff bf ff c3 ff 07 00 07 00 ................
0010: f9 ff 09 00 06 00 0c 00 16 00 fe ff ea ff 10 00 ................
0020: 21 00 01 00 e3 ff ce ff d8 ff f3 ff f4 ff 0f 00 !...............
2009-09-15 18:36:11.758191 > HCI Event: Disconn Complete (0x05) plen 4
status 0x00 handle 6 reason 0x22
Reason: LMP Response Timeout
2009-09-15 18:36:11.908200 > HCI Event: Disconn Complete (0x05) plen 4
status 0x00 handle 11 reason 0x22
Reason: LMP Response Timeout
After this, *all connections with every device* are terminated (note
that in the above sequence handle 11 was disconnected as well) and
cannot be restarted without unplugging the dongle ('hcitool reset'
operates but is ineffective) and restarting the daemon. Again, I'd
welcome any suggestions for further experimentation. I do not have a
sniffer.
Thanks,
Peter Hurley
Peter Hurley wrote:
> While attempting to setup a Motorola S9 headset with a BCM2045-based
> USB dongle (Dell-branded Logitech device), I've observed some strange
> eSCO behavior. I'm running 64-bit 2.6.31 kernel with bluez 4.52.
>
> Behavior # 1: when attempting a SCO connection, frequently the
> connection is rejected with Reserved Slot Violation status return from
> the Synchronous Connect Complete event. The SCO connection
> occasionally succeeds as an eSCO connection in CVSD mode. I've been
> experimenting with this for a while. (After some more observation, it
> may be that the successful path is preceded by a mode change to sniff
> mode) Any ideas?
>
> Behavior # 2: The bt receiver's LM crashes when the eSCO connection
> is disconnected (here's the hcidump):
>
>
> After this, *all connections with every device* are terminated (note
> that in the above sequence handle 11 was disconnected as well) and
> cannot be restarted without unplugging the dongle ('hcitool reset'
> operates but is ineffective) and restarting the daemon. Again, I'd
> welcome any suggestions for further experimentation. I do not have a
> sniffer.
>
> Thanks,
> Peter Hurley
Answered my own question by discovering the sco kernel module parameter,
'disable_esco'. However, it doesn't make sense to me that one device
incompatibility disables an entire transport type. Wouldn't it be
better if the user-space daemon controlled (or at least had the ability
to override) which transport was attempted? At least, control would be
finer-grained (e.g., only HSP profiles could optionally connect to
SCO-only). The sco driver has no idea that the connection attempt is
being driven for a headset.
Regards,
Peter