Re: [Bluez-devel] Re: Problems with anycom usb dongle

[Marcel Holtmann <marcel@holtmann.org>]

Hi Steven,

> >                                        As far as I know, the connection
> > handle from the link manager must not be the same connection handle used
> 
> I think you mean 'need not' not 'must not'.

oh yes, right. Germans (especially I) tend to translate this wrong :)

> > on the HCI. Feel free to correct me, because I never really looked under
> > the HCI layer in that detail.
> 
> Correct. The LMP SCO handle is an 8 bit number in the range 1 to 255.
> The HCI SCO handle is a 12 bit number in the range 0 to 0x0eff.
> 
> LMP SCO handles are unique per piconet and are assigned by the master.
> If a device is a participant in multiple piconets then it may see the
> same LMP handle on different networks. The LM must distinguish SCO
> links using the (piconet, handle) pair.
> 
> HCI SCO handles are unique per host<->controller link. However, the
> same HCI SCO handle may be being used by different devices in a
> piconet to refer to different SCO links.
> 
> The LMP SCO handle is shared between the two devices in a SCO link
> (this allows the devices to distinguish multiple SCO links so that they
> agree on which link is to disconnect, for example).
> 
> The HCI SCO handles are not shared between the two devices. The two
> hosts may see different handles.

And there can't be a SCO and an ACL link with the same handle, right?

However the problems is that we see a SCO data packet with HCI handle 0
and zero data len, which should not be send up to the HCI. Basically I
think we must drop this directly in hci_usb driver and not even send it
up to BlueZ HCI core. Actually I tend to simply mark the SCO support of
this dongle broken.

Regards

Marcel




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