Re: SDP limiting connections?

On 06/02/2008, Marcel Holtmann <[email protected]> wrote:
> >
> > [snip]
> > In short, it looks as if the BlueZ SDP server is not responding at all
> > whilst my application has two current SPP connections.  I don't know
> > if that's what's actually happening, but that's how the symptoms
> > appear.
>
> if you don't see anything in hcidump from the other devices, then it is
> not a SDP servers problem. Would would see connection attempts.
>
> My guess is that both connection are as slaves. Check with "hcitool con"
> and in that case the chip is pretty much busy keeping up. So you need to
> have them to role-switch (RFCOMM_LM_MASTER).

Initial investigations show that your theory is correct (unsurprisingly!).

If we have two connections, "hcitool con" shows:
Connections:
  > ACL 00:18:0F:B3:5B:4D handle 47 state 1 lm SLAVE
  > ACL 00:19:2D:E2:0A:AA handle 42 state 1 lm SLAVE

I can switch role using "hcitool sr <bdaddr>", a given connection, but
it seems that this fails for the first connection.  ie, if I try this
for the first connection it fails, but if I try it for the 2nd, 3rd,
etc it succeeds.  The failure looks like this:

< HCI Command: Switch Role (0x02|0x000b) plen 7
    bdaddr 00:17:B0:B2:5C:7B role 0x00
    Role: Master
> HCI Event: Command Status (0x0f) plen 4
    Switch Role (0x02|0x000b) status 0x0c ncmd 1
    Error: Command Disallowed

I'm guessing this is a function of the protocol, not an application
error, so I'm not too worried about it. Most importantly, your
suggestion worked :)  If I do a role switch for each connection as it
is made (with the exception of the first connection which fails to
switch), I can have more than two SPP connections.

One other question, I can't see a way of performing the role switch
via dbus.  Is there a way to do this?

Thanks for your help.

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