Cannot connect bluetooth remote control to SBC running linux

Question

I am running a buildroot-generated linux image (kernel 4.11.2) on a nanopi NEO air board, and I struggle to connect to my ruwido remote control.
I can see it when I scan the devices using hcitool :

# hcitool lescan
LE Scan ...
<snip>
5C:F8:21:85:8E:67 ruwido
<snip>

But I cannot get a connection (it acts like the remote is not here) :

# hcitool cc 5C:F8:21:85:8E:67
Can't create connection: Input/output error

The only thing I can do is get some information about it :

# hcitool leinfo 5C:F8:21:85:8E:67
Requesting information ...
        Handle: 64 (0x0040)
        LMP Version: 4.0 (0x6) LMP Subversion: 0x140
        Manufacturer: Texas Instruments Inc. (13)
        Features: 0x01 0x00 0x00 0x00 0x00 0x00 0x00 0x00

I also cannot use bluetoothctl since it doesn't detect my interface, even though it's initialized, bluetoothd is running and the modules are loaded :

# lsmod
Module                  Size  Used by
bnep                   20480  2
hci_uart               61440  1
btbcm                  16384  1 hci_uart
btqca                  16384  1 hci_uart
btintel                16384  1 hci_uart
bluetooth             348160  12 hci_uart,btintel,btqca,bnep,btbcm
brcmfmac              245760  0
brcmutil               16384  1 brcmfmac
sunxi_cir              16384  0
# ps -e | grep bluetooth
  553 root     /usr/sbin/bluetoothd
  731 root     grep bluetooth
# sudo hciconfig -a
hci0:   Type: Primary  Bus: UART
        BD Address: F7:93:3E:74:CF:62  ACL MTU: 1021:8  SCO MTU: 64:1
        UP RUNNING 
        RX bytes:12593 acl:7 sco:0 events:292 errors:0
        TX bytes:2050 acl:4 sco:0 commands:155 errors:0
        Features: 0xbf 0xfe 0xcf 0xfe 0xdb 0xff 0x7b 0x87
        Packet type: DM1 DM3 DM5 DH1 DH3 DH5 HV1 HV2 HV3 
        Link policy: RSWITCH SNIFF 
        Link mode: SLAVE ACCEPT 
        Name: 'NanoPi-NEO-Air'
        Class: 0x000000
        Service Classes: Unspecified
        Device Class: Miscellaneous, 
        HCI Version: 4.1 (0x7)  Revision: 0x0
        LMP Version: 4.1 (0x7)  Subversion: 0x2209
        Manufacturer: Broadcom Corporation (15)

# bluetoothctl 
Agent registered
[bluetooth]# power on
No default controller available

My question is, how do I get the remote paired and connected to the board ? It doesn't matter if it's through hcitool, bluetoothctl or another tool.

Update

Thanks to Prabhakar Lad's comment, bluetoothctl is now detecting the interface, however the problem still remains and the problem seems to have narrowed :

# rfkill unblock all
# hciconfig hci0 up
# hciconfig -a
hci0:   Type: Primary  Bus: UART
        BD Address: AA:AA:AA:AA:AA:AA  ACL MTU: 1021:8  SCO MTU: 64:1
        UP RUNNING PSCAN 
        RX bytes:1930 acl:0 sco:0 events:101 errors:0
        TX bytes:1587 acl:0 sco:0 commands:103 errors:0
        Features: 0xbf 0xfe 0xcf 0xfe 0xdb 0xff 0x7b 0x87
        Packet type: DM1 DM3 DM5 DH1 DH3 DH5 HV1 HV2 HV3 
        Link policy: RSWITCH SNIFF 
        Link mode: SLAVE ACCEPT 
        Name: 'BlueZ 5.47'
        Class: 0x000000
        Service Classes: Unspecified
        Device Class: Miscellaneous, 
        HCI Version: 4.1 (0x7)  Revision: 0x0
        LMP Version: 4.1 (0x7)  Subversion: 0x2209
        Manufacturer: Broadcom Corporation (15)

# bluetoothctl
[NEW] Controller F7:93:3E:74:CF:62 BlueZ 5.47 [default]
[NEW] Device 5C:F8:21:85:8E:67 ruwido
Agent registered
[bluetooth]# agent on
Agent is already registered
[bluetooth]# power on
Changing power on succeeded
[bluetooth]# scan on
Discovery started
[CHG] Controller F7:93:3E:74:CF:62 Discovering: yes
<snip>
[NEW] Device 5C:F8:21:85:8E:67 ruwido
<snip>
[bluetooth]# scan off
<snip>
[CHG] Device 5C:F8:21:85:8E:67 RSSI is nil
<snip>
[CHG] Controller F7:93:3E:74:CF:62 Discovering: no
Discovery stopped
[bluetooth]# pair 5C:F8:21:85:8E:67
Attempting to pair with 5C:F8:21:85:8E:67
[CHG] Device 5C:F8:21:85:8E:67 Connected: yes
[ruwido]# [  501.424858] Bluetooth: hci0 unexpected SMP command 0x0b from 5c:f8:21:85:8e:67
[CHG] Device 5C:F8:21:85:8E:67 Connected: no
[bluetooth]# pair 5C:F8:21:85:8E:67
Attempting to pair with 5C:F8:21:85:8E:67
Failed to pair: org.bluez.Error.ConnectionAttemptFailed

The SMP error seems to be related to bluetooth low-energy security, so am I supposed to use a different tool for pairing ?

Additional information

I actually use the busybox init system with bluetooth init scripts I found in the manufacturer's image (which is nanopi-neo-air_FriendlyCore-Xenial_4.11.2_20171113.img) and adapted so that they could be used with busybox init (the init system on the image is systemd/upstart).
So I have two files :

• /etc/init.d/S35brcm_patchram_plus : patches firmware (the card uses an AMPAK ap6212 bluetooth/wifi combo module)
• /etc/init.d/S38bluetooth : starts bluetoothd

I use bluez 5.47 with the following options in buildroot 2017.08.1 :

BR2_PACKAGE_BLUEZ_TOOLS=y
# BR2_PACKAGE_BLUEZ_UTILS is not set
BR2_PACKAGE_BLUEZ5_UTILS=y
BR2_PACKAGE_BLUEZ5_UTILS_OBEX=y
BR2_PACKAGE_BLUEZ5_UTILS_CLIENT=y
BR2_PACKAGE_BLUEZ5_UTILS_DEPRECATED=y
# BR2_PACKAGE_BLUEZ5_UTILS_EXPERIMENTAL is not set
# BR2_PACKAGE_BLUEZ5_PLUGINS_HEALTH is not set
# BR2_PACKAGE_BLUEZ5_PLUGINS_MIDI is not set
# BR2_PACKAGE_BLUEZ5_PLUGINS_NFC is not set
# BR2_PACKAGE_BLUEZ5_PLUGINS_SAP is not set
BR2_PACKAGE_BLUEZ5_UTILS_TEST=y
# BR2_PACKAGE_BLUEZ5_UTILS_GATTTOOL is not set

Answer 1

You didnt go through my complete post, you need to perform following steps after you have done with rfkill and service restart:

a] bluetoothctl

Start the tool, this should detect the controller

b] [bluetooth]# agent on

Turn on the pairing agent

c] [bluetooth]# scan on

Let bluez detect your device, look in my post it should print you baddr (5C:F8:21:85:8E:67)

d] [bluetooth]# scan off

Turn off scanning once your device is discovered

e] [bluetooth]# pair 5C:F8:21:85:8E:67

Now pair to the device

It should now be paired. Note: you cannot pair a device until the bluez has scanned it.