• Marcel Holtmann's avatar
    Bluetooth: Add different pairing timeout for Legacy Pairing · 052b30b0
    Marcel Holtmann authored
    The Bluetooth stack uses a reference counting for all established ACL
    links and if no user (L2CAP connection) is present, the link will be
    terminated to save power. The problem part is the dedicated pairing
    when using Legacy Pairing (Bluetooth 2.0 and before). At that point
    no user is present and pairing attempts will be disconnected within
    10 seconds or less. In previous kernel version this was not a problem
    since the disconnect timeout wasn't triggered on incoming connections
    for the first time. However this caused issues with broken host stacks
    that kept the connections around after dedicated pairing. When the
    support for Simple Pairing got added, the link establishment procedure
    needed to be changed and now causes issues when using Legacy Pairing
    
    When using Simple Pairing it is possible to do a proper reference
    counting of ACL link users. With Legacy Pairing this is not possible
    since the specification is unclear in some areas and too many broken
    Bluetooth devices have already been deployed. So instead of trying to
    deal with all the broken devices, a special pairing timeout will be
    introduced that increases the timeout to 60 seconds when pairing is
    triggered.
    
    If a broken devices now puts the stack into an unforeseen state, the
    worst that happens is the disconnect timeout triggers after 120 seconds
    instead of 4 seconds. This allows successful pairings with legacy and
    broken devices now.
    
    Based on a report by Johan Hedberg <johan.hedberg@nokia.com>
    Signed-off-by: default avatarMarcel Holtmann <marcel@holtmann.org>
    052b30b0
hci.h 23 KB