The L2CAP spec recommends specific retransmit and monitor timeouts for
ERTM channels that are on AMP controllers. These timeouts are
calculated from the AMP controller's best effort flush timeout.
BR/EDR controllers use the default retransmit and monitor timeouts.
Signed-off-by: Mat Martineau <mathewm@xxxxxxxxxxxxxx>
---
net/bluetooth/l2cap_core.c | 47 ++++++++++++++++++++++++++++++++++++++++------
1 file changed, 41 insertions(+), 6 deletions(-)
diff --git a/net/bluetooth/l2cap_core.c b/net/bluetooth/l2cap_core.c
index 0a7df20..e7c2efc 100644
--- a/net/bluetooth/l2cap_core.c
+++ b/net/bluetooth/l2cap_core.c
@@ -2924,6 +2924,44 @@ static inline bool __l2cap_efs_supported(struct l2cap_chan *chan)
return enable_hs && chan->conn->feat_mask & L2CAP_FEAT_EXT_FLOW;
}
+static void __l2cap_set_ertm_timeouts(struct l2cap_chan *chan,
+ struct l2cap_conf_rfc *rfc)
+{
+ if (chan->local_amp_id && chan->hs_hcon) {
+ u64 ertm_to = chan->hs_hcon->hdev->amp_be_flush_to;
+
+ /* Class 1 devices have must have ERTM timeouts
+ * exceeding the Link Supervision Timeout. The
+ * default Link Supervision Timeout for AMP
+ * controllers is 10 seconds.
+ *
+ * Class 1 devices use 0xffffffff for their
+ * best-effort flush timeout, so the clamping logic
+ * will result in a timeout that meets the above
+ * requirement. ERTM timeouts are 16-bit values, so
+ * the maximum timeout is 65.535 seconds.
+ */
+
+ /* Convert timeout to milliseconds and round */
+ ertm_to = div_u64(ertm_to + 999, 1000);
+
+ /* This is the recommended formula for class 2 devices
+ * that start ERTM timers when packets are sent to the
+ * controller.
+ */
+ ertm_to = 3 * ertm_to + 500;
+
+ if (ertm_to > 0xffff)
+ ertm_to = 0xffff;
+
+ rfc->retrans_timeout = cpu_to_le16((u16) ertm_to);
+ rfc->monitor_timeout = rfc->retrans_timeout;
+ } else {
+ rfc->retrans_timeout = __constant_cpu_to_le16(L2CAP_DEFAULT_RETRANS_TO);
+ rfc->monitor_timeout = __constant_cpu_to_le16(L2CAP_DEFAULT_MONITOR_TO);
+ }
+}
+
static inline void l2cap_txwin_setup(struct l2cap_chan *chan)
{
if (chan->tx_win > L2CAP_DEFAULT_TX_WINDOW &&
@@ -2990,8 +3028,8 @@ done:
case L2CAP_MODE_ERTM:
rfc.mode = L2CAP_MODE_ERTM;
rfc.max_transmit = chan->max_tx;
- rfc.retrans_timeout = 0;
- rfc.monitor_timeout = 0;
+
+ __l2cap_set_ertm_timeouts(chan, &rfc);
size = min_t(u16, L2CAP_DEFAULT_MAX_PDU_SIZE, chan->conn->mtu -
L2CAP_EXT_HDR_SIZE -
@@ -3223,10 +3261,7 @@ done:
rfc.max_pdu_size = cpu_to_le16(size);
chan->remote_mps = size;
- rfc.retrans_timeout =
- __constant_cpu_to_le16(L2CAP_DEFAULT_RETRANS_TO);
- rfc.monitor_timeout =
- __constant_cpu_to_le16(L2CAP_DEFAULT_MONITOR_TO);
+ __l2cap_set_ertm_timeouts(chan, &rfc);
set_bit(CONF_MODE_DONE, &chan->conf_state);
--
1.7.12
--
Mat Martineau
The Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
hosted by The Linux Foundation
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