Re: BD address changed but pairing failed

[Marcel Holtmann <marcel@holtmann.org>]

Hi Sebastien,

> >> I'm currently facing an issue regarding the pairing of BT devices after
> >> having change the BD_Addr.
> >>
> >>
> >> I use a TI chip and also use hci command or bdaddr script to modify the
> >> bd_addr
> >>
> >> I'm also using the bluez-4.69
> >>
> >> I change the BD_Addr using the bdaddr scripts provided into the bluez src.
> >>
> >> When other devices scan me, the new address is seen but hciconfig still show
> >> the old BD address.
> >>
> >> I have sent the hcitool cmd to read the bd_addr and after the hciconfig
> >> return the one.
> >>
> >> I'm discoverable with the new BD address.
> >>
> >> But When I try to pair an A2DP headset or BT Keyboard/Mouse it failed since
> >> BD_Addr change.
> >>
> >> I have try to use directly the hcitool cmd using the vendor specific command
> >> but I got the same result.
> >>
> >> I have tried to kill bluetooth daemon and restart it after having change the
> >> bd_addr. Still failing.
> >>
> >> I have tried to kill bluetooth daemon before changing the BD adress and
> >> start it after the change it still fail.
> >>
> >> I have also tried to power on/off interface. still the issue
> >>
> >> I think that something is "broken" is bluez when the BD_Addr is changed.
> >>
> >> Is someone already seen this issue ?
> > I don't think you are suppose to change the address like that, it is
> > supposed to be done once in the chip initialization and then keep it
> > like that forever, so I guess there is something wrong if the chip is
> > already initialize with the wrong address. What are you trying achieve
> > with this?
> >
> Surely not but regarding some tests scripts I have seen on bluez, I 
> suppose that's possible. Perhaps, some chips support and other don't.
> 
> I have tried to change the BD_Address during the BT initialization and 
> prior any HCI command sent to the chip and it works.

all of them needed a special warm reset. The HCI_Reset was never enough.
I might work on some Broadcom chips this way, but all others do need
special reset magic.

> I expected the same behavior than observed on WLAN :  I have changed the 
> WLAN MAC address after and everything works fine.

The WiFi MAC address is different than a BD_ADDR. You can NOT expect any
similar behavior. That they happen to be both IEEE addresses means
nothing at all.

Regards

Marcel