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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: Marcel Holtmann <marcel@holtmann.org> |
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| .. | ||
| bluetooth.h | ||
| hci_core.h | ||
| hci.h | ||
| l2cap.h | ||
| rfcomm.h | ||
| sco.h | ||