Bluetooth: Add SCO fallback for eSCO connection attempts

When attempting to setup eSCO connections it can happen that some link
manager implementations fail to properly negotiate the eSCO parameters
and thus fail the eSCO setup. Normally the link manager is responsible
for the negotiation of the parameters and actually fallback to SCO if
no agreement can be reached. In cases where the link manager is just too
stupid, then at least try to establish a SCO link if eSCO fails.

For the Bluetooth devices with EDR support this includes handling packet
types of EDR basebands. This is particular tricky since for the EDR the
logic of enabling/disabling one specific packet type is turned around.
This fix contains an extra bitmask to disable eSCO EDR packet when
trying to fallback to a SCO connection.

Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

1 files changed, 16 insertions, 0 deletions

diff --git a/net/bluetooth/hci_event.c b/net/bluetooth/hci_event.c
index 014fc8b320ba..899b8991a466 100644
--- a/net/bluetooth/hci_event.c
+++ b/net/bluetooth/hci_event.c
@@ -484,6 +484,15 @@ static void hci_cc_read_local_features(struct hci_dev *hdev, struct sk_buff *skb
         if (hdev->features[4] & LMP_EV5)
                 hdev->esco_type |= (ESCO_EV5);
 
+        if (hdev->features[5] & LMP_EDR_ESCO_2M)
+                hdev->esco_type |= (ESCO_2EV3);
+
+        if (hdev->features[5] & LMP_EDR_ESCO_3M)
+                hdev->esco_type |= (ESCO_3EV3);
+
+        if (hdev->features[5] & LMP_EDR_3S_ESCO)
+                hdev->esco_type |= (ESCO_2EV5 | ESCO_3EV5);
+
         BT_DBG("%s features 0x%.2x%.2x%.2x%.2x%.2x%.2x%.2x%.2x", hdev->name,
                                         hdev->features[0], hdev->features[1],
                                         hdev->features[2], hdev->features[3],
@@ -1639,6 +1648,13 @@ static inline void hci_sync_conn_complete_evt(struct hci_dev *hdev, struct sk_bu
                 conn->type = SCO_LINK;
         }
 
+        if (conn->out && ev->status == 0x1c && conn->attempt < 2) {
+                conn->pkt_type = (hdev->esco_type & SCO_ESCO_MASK) |
+                                        (hdev->esco_type & EDR_ESCO_MASK);
+                hci_setup_sync(conn, conn->link->handle);
+                goto unlock;
+        }
+
         if (!ev->status) {
                 conn->handle = __le16_to_cpu(ev->handle);
                 conn->state  = BT_CONNECTED;