[Bluez-devel] Jumpy cursor with Wacom Graphire Bluetooth

[Robert Siemer <Robert.Siemer@backsla.sh>]

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Hello everybody!

hcidump is telling me that my tablet sends packets only after six pixels
of mouse movement or together with button events. - I suppose that some
parameters exchanged during connection handshake are the cause.

-Who is making the connectinon? (hidp kernel module?)
-Who can/could influence it's outcome? (hidd userspace daemon? Plays
 hcid an important role?)
-Has the latency thing something to do with it?
-Which spec should I first dig into - Bluetooth or HID?


I played already around with role switching (forced, voluntary from the
tablet, none). - Has no influence.

A "hcidump -w" connection dumps are attached. Here inline some tablet
mouse movements:

panorama:/tmp# hcidump -V -X
HCI sniffer - Bluetooth packet analyzer ver 1.23
device: hci0 snap_len: 1028 filter: 0xffffffff
> ACL data: handle 41 flags 0x02 dlen 10
    L2CAP(d): cid 0x0041 len 6 [psm 0]
      0000: a1 02 00 fa 02 00                                 ......
                     ^^ ^^
Curser moved six "entities" to the left. While already sending a packet,
the tablet also reports some down movements ("02").

> ACL data: handle 41 flags 0x02 dlen 13
    L2CAP(d): cid 0x0041 len 9 [psm 0]
      0000: a1 03 00 00 00 00 00 00  20                       ........ 
> ACL data: handle 41 flags 0x02 dlen 10
    L2CAP(d): cid 0x0041 len 6 [psm 0]
      0000: a1 02 00 fd 06 00                                 ......
                     ^^ ^^
The same, but moved 06 entities ("pixel") down. Obviously I also moved 3
pixels left (0xfd).

> ACL data: handle 41 flags 0x02 dlen 13
    L2CAP(d): cid 0x0041 len 9 [psm 0]
      0000: a1 03 00 00 00 00 00 00  20                       ........ 



Thanks for comments!

Robert

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[-- Attachment #4: hcidump.connect_voluntary_rswitch.bin --]
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