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Date: Tue, 20 Jan 2009 12:00:47 +0530
From: sushil <skdeka@gmail.com>
To: linux-bluetooth@vger.kernel.org
Subject: HID control channel req issue
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Hi all,

In HID Host initiated connection to HID device, Host is sending L2CAP
control channel request message twice to the device. The hcidump logs
are as follows


< ACL data: handle 47 flags 0x02 dlen 12

    L2CAP(s): Connect req: psm 17 scid 0x0040

> HCI Event: Number of Completed Packets (0x13) plen 5

    handle 47 packets 1

> ACL data: handle 47 flags 0x02 dlen 16

    L2CAP(s): Connect rsp: dcid 0x0040 scid 0x0040 result 1 status 0

      Connection pending - No futher information available



> HCI Event: Link Key Request (0x17) plen 6

    bdaddr 00:02:5B:02:97:6E

< HCI Command: Link Key Request Negative Reply (0x01|0x000c) plen 6

    bdaddr 00:02:5B:02:97:6E

> HCI Event: Command Complete (0x0e) plen 10

    Link Key Request Negative Reply (0x01|0x000c) ncmd 1

    status 0x00 bdaddr 00:02:5B:02:97:6E


> HCI Event: PIN Code Request (0x16) plen 6

    bdaddr 00:02:5B:02:97:6E

< HCI Command: PIN Code Request Reply (0x01|0x000d) plen 23

    bdaddr 00:02:5B:02:97:6E len 4 pin '0000'

> HCI Event: Command Complete (0x0e) plen 10

    PIN Code Request Reply (0x01|0x000d) ncmd 1

    status 0x00 bdaddr 00:02:5B:02:97:6E

> HCI Event: Link Key Notification (0x18) plen 23

    bdaddr 00:02:5B:02:97:6E key B00AC8478BC923A0E1B269C5BB510584 type 0

    Type: Combination Key

> HCI Event: Encrypt Change (0x08) plen 4

    status 0x00 handle 47 encrypt 0x01


< ACL data: handle 47 flags 0x02 dlen 12

    L2CAP(s): Connect req: psm 17 scid 0x0040

> ACL data: handle 47 flags 0x02 dlen 16

    L2CAP(s): Connect rsp: dcid 0x0040 scid 0x0040 result 0 status 0

      Connection successful

< ACL data: handle 47 flags 0x02 dlen 12

    L2CAP(s): Config req: dcid 0x0040 flags 0x00 clen 0

> HCI Event: Number of Completed Packets (0x13) plen 5

    handle 47 packets 1


After looking into the code, in l2cap.c function l2cap_encrypt_cfm()

If state is BT_CONNECT and status is 0, host again sends the second
L2cap_conn_req for control channel.


I am not sure even if encrypt== 0x01, bluez needs to send the second
L2cap_connect_req for control channel.

Can anyone please clarify this.


Thanks,
Skdeka