Re: [Bluez-devel] Fwd: reduce hci connect time

[Arnaud Mouiche <arnaud.mouiche@inventel.fr>]

At 10:29 06/09/2004, Marcel Holtmann wrote:
>Hi Murdok,
>
> > I'm trying to reduce the time of HCI connect using the clock offset in the
> > hcitool create connection command.
> > So I modified hcitool.c (present in attach) adding the clkoffset parameter
> > on hci_create_connection:
> >
> >  if (hci_create_connection(dd, &bdaddr, htobs(ptype), clkoffset , role,
> > &handle, 25000) < 0)
> >                 perror("Can't create connection");
> >
> > and change the code for insert that in the command with this syntax:
> >
> > hcitool cc --clkos <clkoffset-in-decimal> <BDADDR>;
> >
> > then I add a printf into hcitool inq for print the clkoffset in decimal
> > and try to insert this in the connection command, b
> > ut the time of connect do not change!
> >
> > Later, during other test I take a mistake using a wrong clockoffset in the
> > connect command and the time of the connection w
> > as redused under 100 ms (with the slave in continuos page scan mode).
> >
> > So I write a little bash script for test and I find a stange class of value
> > to reduce this time of connection, but I can't
> > understanding the logic.
> >
> > Where I mistake?
> > Why if I insert the same value returned from hci inqiry the connection do
> > not reduce its time?
> > There is a bug in the code or I wrong using some function?
> >
> > In attach you can find:
> > the hcitool.c code (modified)
> > a dump with a hci inquiry, and an hci connect with the same value of
> >  clokoffset bash script for trying a lot value of clkoffset
>
>check the specification on how to modify the clock offset for making it
>a valid value for the create connection command.
>
>Your patch is not really needed, because there is no need to use the
>"hcitool cc ..." command. I wrote it many times that this is only a
>command for debugging and not for normal use. The kernel has its own
>inquiry cache and it uses the clock offset for every connection created
>through by the kernel.
>
>Regards
>
>Marcel

Hi murdok

The page scan repetition mode is also an important information for create 
connection, to help the connection. I don't know if the information is 
cached by inquiry result and/or if it is used corretly in 
HCI_CREAT_CONNECTION HCI command.

May be you can check this and see if it helps in your situation.

arnaud




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