2014-06-26 15:57:26

by d.eriksson

[permalink] [raw]
Subject: BLE (HOGP) Direct Adv -> Re-connect request, mysterious ~5sec latency

Hi,

I'm trying to figure out why we get a 4-5sec delay between a BLE reconnect (direct-advertise) to when the first event pops up in the kernel/bluez.

I can see in wireshark that as soon as my BLE-device advertises, the TI-BLE chip on the linux 3.13 host-side responds immediately, but from here to when we get the hid device up and ready, it takes another 4-5seconds. Any ideas why!?


See the btmon + corresponding "wire-shark dump" (made using a wireless sniffer) between ~105-110sec.
(note that the second offset between the two are off by ~2sec)

https://mega.co.nz/#!LQlVQQ5J!ouwcuee61u3cqwtVqIMVjRf5WgXBXDQJvelClDS4WDU


on the btmon side you can see the below behaviour



> ACL Data RX: Handle 1025 flags 0x02 dlen 12 [hci0] 107.714506
ATT: Read Response (0x0b) len 7
Value: 02672302000100
> HCI Event: Number of Completed Packets (0x13) plen 5 [hci0] 107.742699
Num handles: 1
Handle: 1025
Count: 1
> ACL Data RX: Handle 1025 flags 0x02 dlen 16
[hci0] 111.638371
LE L2CAP: Connection Parameter Update Request (0x12) ident 2 len 8
Min interval: 6
Max interval: 24
Slave latency: 6
Timeout multiplier: 30
< ACL Data TX: Handle 1025 flags 0x00 dlen 10 [hci0] 111.638484
LE L2CAP: Connection Parameter Update Response (0x13) ident 2 len 2
Result: Connection Parameters accepted (0x0000)
< HCI Command: LE Connection Update (0x08|0x0013) plen 14 [hci0] 111.638531
Handle: 1025
Min connection interval: 7.50 msec (0x0006)
Max connection interval: 30.00 msec (0x0018)
Connection latency: 0x0006
Supervision timeout: 300 msec (0x001e)
Min connection length: 0.625 msec (0x0001)
Max connection length: 0.625 msec (0x0001)
> HCI Event: Command Status (0x0f) plen 4 [hci0] 111.639402
LE Connection Update (0x08|0x0013) ncmd 1
Status: Success (0x00)



best David