Bluetooth: Use non-flushable by default L2CAP data packets
Modification of Nick Pelly <npelly@google.com> patch.
With Bluetooth 2.1 ACL packets can be flushable or non-flushable. This commit
makes ACL data packets non-flushable by default on compatible chipsets, and
adds the BT_FLUSHABLE socket option to explicitly request flushable ACL
data packets for a given L2CAP socket. This is useful for A2DP data which can
be safely discarded if it can not be delivered within a short time (while
other ACL data should not be discarded).
Note that making ACL data flushable has no effect unless the automatic flush
timeout for that ACL link is changed from its default of 0 (infinite).
Default packet types (for compatible chipsets):
Frame 34: 13 bytes on wire (104 bits), 13 bytes captured (104 bits)
Bluetooth HCI H4
Bluetooth HCI ACL Packet
.... 0000 0000 0010 = Connection Handle: 0x0002
..00 .... .... .... = PB Flag: First Non-automatically Flushable Packet (0)
00.. .... .... .... = BC Flag: Point-To-Point (0)
Data Total Length: 8
Bluetooth L2CAP Packet
After setting BT_FLUSHABLE
(sock.setsockopt(274 /*SOL_BLUETOOTH*/, 8 /* BT_FLUSHABLE */, 1 /* flush */))
Frame 34: 13 bytes on wire (104 bits), 13 bytes captured (104 bits)
Bluetooth HCI H4
Bluetooth HCI ACL Packet
.... 0000 0000 0010 = Connection Handle: 0x0002
..10 .... .... .... = PB Flag: First Automatically Flushable Packet (2)
00.. .... .... .... = BC Flag: Point-To-Point (0)
Data Total Length: 8
Bluetooth L2CAP Packet
Signed-off-by: Andrei Emeltchenko <andrei.emeltchenko@nokia.com>
Signed-off-by: Gustavo F. Padovan <padovan@profusion.mobi>
diff --git a/include/net/bluetooth/hci.h b/include/net/bluetooth/hci.h
index 29a7a8c..5d033dc 100644
--- a/include/net/bluetooth/hci.h
+++ b/include/net/bluetooth/hci.h
@@ -150,6 +150,7 @@
#define EDR_ESCO_MASK (ESCO_2EV3 | ESCO_3EV3 | ESCO_2EV5 | ESCO_3EV5)
/* ACL flags */
+#define ACL_START_NO_FLUSH 0x00
#define ACL_CONT 0x01
#define ACL_START 0x02
#define ACL_ACTIVE_BCAST 0x04
@@ -194,6 +195,7 @@
#define LMP_EDR_3S_ESCO 0x80
#define LMP_SIMPLE_PAIR 0x08
+#define LMP_NO_FLUSH 0x40
/* Connection modes */
#define HCI_CM_ACTIVE 0x0000