Re: Unknown Connection Identifier

On Tue, Nov 24, 2015 at 12:00 PM, Marcel Holtmann [off-list ref]
wrote:

Hi Francois,

quoted

Thanks both of you for your input.

Here are my 100% reproducible steps:
- Restart bluetoothd to start fresh
- Remove cached device (remove 88:0F:10:9D:EB:42)
- Run basic scan (scan on)
- Wait for the device to pop up in results and stop scan (scan off)
- Try to connect to it (connect 88:0F:10:9D:EB:42)

As you can read below I now have 2 "LE Connection Complete (0x01)"

events.

quoted

Bluetooth monitor ver 5.35
= New Index: A4:17:31:78:A6:04 (BR/EDR,USB,hci0)
               [hci0] 0.624321
< HCI Command: LE Add Device To White List (0x08|0x0011) plen 7
              [hci0] 11.038826
       Address type: Public (0x00)
       Address: 88:0F:10:9D:EB:42 (OUI 88-0F-10)

quoted

HCI Event: Command Complete (0x0e) plen 4

             [hci0] 11.040084

quoted

     LE Add Device To White List (0x08|0x0011) ncmd 1
       Status: Success (0x00)
< HCI Command: LE Set Scan Parameters (0x08|0x000b) plen 7
              [hci0] 11.040125
       Type: Passive (0x00)
       Interval: 60.000 msec (0x0060)
       Window: 30.000 msec (0x0030)
       Own address type: Public (0x00)
       Filter policy: Ignore not in white list (0x01)

quoted

HCI Event: Command Complete (0x0e) plen 4

             [hci0] 11.041085

quoted

     LE Set Scan Parameters (0x08|0x000b) ncmd 1
       Status: Success (0x00)
< HCI Command: LE Set Scan Enable (0x08|0x000c) plen 2
              [hci0] 11.041134
       Scanning: Enabled (0x01)
       Filter duplicates: Enabled (0x01)

quoted

HCI Event: Command Complete (0x0e) plen 4

             [hci0] 11.042084

quoted

     LE Set Scan Enable (0x08|0x000c) ncmd 1
       Status: Success (0x00)

quoted

HCI Event: LE Meta Event (0x3e) plen 43

             [hci0] 15.668141

quoted

     LE Advertising Report (0x02)
       Num reports: 1
       Event type: Connectable undirected - ADV_IND (0x00)
       Address type: Public (0x00)
       Address: 88:0F:10:9D:EB:42 (OUI 88-0F-10)
       Data length: 31
       Flags: 0x06
         LE General Discoverable Mode
         BR/EDR Not Supported
       Company: Anhui Huami Information Technology Co., Ltd. (343)
         Data: 00f70b676930f4c909f4a5acd792a299ff02880f109deb42
       RSSI: -59 dBm (0xc5)
< HCI Command: LE Set Scan Enable (0x08|0x000c) plen 2
              [hci0] 15.668289
       Scanning: Disabled (0x00)
       Filter duplicates: Disabled (0x00)

quoted

HCI Event: Command Complete (0x0e) plen 4

             [hci0] 15.669062

quoted

     LE Set Scan Enable (0x08|0x000c) ncmd 1
       Status: Success (0x00)
< HCI Command: LE Create Connection (0x08|0x000d) plen 25
              [hci0] 15.669171
       Scan interval: 60.000 msec (0x0060)
       Scan window: 30.000 msec (0x0030)

we might should have the LE Create Connection scan with a full duty cycle
here. So it does not miss any advertising PDUs.

Is this something the Linux Bluetooth team is going to address?

quoted

       Filter policy: White list is not used (0x00)
       Peer address type: Public (0x00)
       Peer address: 88:0F:10:9D:EB:42 (OUI 88-0F-10)
       Own address type: Public (0x00)
       Min connection interval: 50.00 msec (0x0028)
       Max connection interval: 70.00 msec (0x0038)
       Connection latency: 0x0000
       Supervision timeout: 420 msec (0x002a)
       Min connection length: 0.000 msec (0x0000)
       Max connection length: 0.000 msec (0x0000)

quoted

HCI Event: Command Status (0x0f) plen 4

             [hci0] 15.670065

quoted

     LE Create Connection (0x08|0x000d) ncmd 1
       Status: Success (0x00)
< HCI Command: LE Create Connection Cancel (0x08|0x000e) plen 0
              [hci0] 17.670566

And I think we need to increase the timeout to something like 4-5 seconds
before we give up and try the next device that might have been found.

For my own curiosity, how does does perform Android Bluetooth stack when
creating a LE connection?
Does it hardcode a 4-5 seconds timeout or does it use other heuristics?

quoted

quoted

HCI Event: Command Complete (0x0e) plen 4

             [hci0] 17.672048

quoted

     LE Create Connection Cancel (0x08|0x000e) ncmd 1
       Status: Success (0x00)

quoted

HCI Event: LE Meta Event (0x3e) plen 19

             [hci0] 17.674036

quoted

     LE Connection Complete (0x01)
       Status: Unknown Connection Identifier (0x02)
       Handle: 32
       Role: Master (0x00)
       Peer address type: Public (0x00)
       Peer address: 88:0F:10:9D:EB:42 (OUI 88-0F-10)
       Connection interval: 67.50 msec (0x0036)
       Connection latency: 0.00 msec (0x0000)
       Supervision timeout: 420 msec (0x002a)
       Master clock accuracy: 0x00
@ Connect Failed: 88:0F:10:9D:EB:42 (1) status 0x02

This one still needs to be fixed. It is a bug. The implementation is too
naive. The unknown connection identifier is actually the success case for
LE Create Connection Cancel command. And since we keep trying until the
connection timeout hits, this is not an error at this point.

Regards

Marcel