Isue with the bleutooth support

Hello i try to use the bleutooth on the HI970 board.
I use the tensorflow linux image.

the bleutooth service start properly
service bluetooth status
● bluetooth.service - Bluetooth service
Loaded: loaded (/lib/systemd/system/bluetooth.service; enabled; vendor preset
Active: active (running) since Thu 2016-11-03 18:16:42 +01; 2 years 2 months
Docs: man:bluetoothd(8)
Main PID: 3391 (bluetoothd)
Status: “Running”
Tasks: 1 (limit: 4915)
CGroup: /system.slice/bluetooth.service
└─3391 /usr/lib/bluetooth/bluetoothd
hciconfig -a

The bleutooth device existe:

hciconfig -a
hci0: Type: Primary Bus: UART
BD Address: 00:00:00:00:00:00 ACL MTU: 0:0 SCO MTU: 0:0
DOWN
RX bytes:0 acl:0 sco:0 events:0 errors:0
TX bytes:0 acl:0 sco:0 commands:0 errors:0
Features: 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00
Packet type: DM1 DH1 HV1
Link policy:
Link mode: SLAVE ACCEPT

but
hcitool dev
Devices:

and …

hciconfig hci0 up
Can’t init device hci0: Input/output error (5)

dmsg

[ 614.060437] [drm] bl_level is 255
[ 614.060440] [drm] bl_level=255.
[ 890.665325] (stc): chnl_id list empty :4
[ 890.665344] (stk) : st_kim_start
[ 890.770392] (stk) :ldisc_install = 1
[ 891.790452] (stk) :ldisc installation timeout
[ 891.794854] (stk) :ldisc_install = 0
[ 892.813735] (stk) : timed out waiting for ldisc to be un-installed
[ 892.926982] (stk) :ldisc_install = 1
[ 893.933731] (stk) :ldisc installation timeout
[ 893.938101] (stk) :ldisc_install = 0
[ 894.957752] (stk) : timed out waiting for ldisc to be un-installed
[ 895.071002] (stk) :ldisc_install = 1
[ 896.077773] (stk) :ldisc installation timeout
[ 896.082196] (stk) :ldisc_install = 0
[ 897.101783] (stk) : timed out waiting for ldisc to be un-installed
[ 897.215044] (stk) :ldisc_install = 1
[ 898.221783] (stk) :ldisc installation timeout
[ 898.226192] (stk) :ldisc_install = 0
[ 899.246559] (stk) : timed out waiting for ldisc to be un-installed
[ 899.359844] (stk) :ldisc_install = 1
[ 900.366564] (stk) :ldisc installation timeout
[ 900.370983] (stk) :ldisc_install = 0
[ 901.389819] (stk) : timed out waiting for ldisc to be un-installed
[ 901.503068] (stk) :ldisc_install = 1
[ 902.509827] (stk) :ldisc installation timeout
[ 902.514241] (stk) :ldisc_install = 0
[ 903.533844] (stk) : timed out waiting for ldisc to be un-installed
[ 903.542106] Bluetooth: st_register failed -22

regards
Olivier