As shown in the schematic diagram below.There may be a critical
scenario in the current code. If the device does not receive an
pure ack sent by the host due to insufficient receive buffer or
other reasons and triggers a retransmission, the host will always
be in an 'out-of-order' state.The state machine will get stuck.
host device
SEQ3,ACK4 --------->
<--------- SEQ4,ACK4
pure ACK ---------> (not received)
(out-of-order) <--------- SEQ4,ACK4(retransmission)
........
(out-of-order) <--------- SEQ4,ACK4(retransmission)
According to the description in the core specification: "whenever
a reliable packet is received, an acknowledgment shall be generated."
we should set H5_TX_ACK_REQ bit to trigger retransmission of pure ack
packet when "out-of-order" occurs.
Signed-off-by: Qiqi Zhang <eddy.zhang@xxxxxxxxxxxxxx>
---
drivers/bluetooth/hci_h5.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/drivers/bluetooth/hci_h5.c b/drivers/bluetooth/hci_h5.c
index 6455bc4fb5bb..d05eaeaa4516 100644
--- a/drivers/bluetooth/hci_h5.c
+++ b/drivers/bluetooth/hci_h5.c
@@ -463,6 +463,8 @@ static int h5_rx_3wire_hdr(struct hci_uart *hu, unsigned char c)
if (H5_HDR_RELIABLE(hdr) && H5_HDR_SEQ(hdr) != h5->tx_ack) {
bt_dev_err(hu->hdev, "Out-of-order packet arrived (%u != %u)",
H5_HDR_SEQ(hdr), h5->tx_ack);
+ set_bit(H5_TX_ACK_REQ, &h5->flags);
+ hci_uart_tx_wakeup(hu);
h5_reset_rx(h5);
return 0;
}
--
2.25.1
