Bluetooth: hci_h5: avoid sending two SYNC messages

Previously, h5_open() called h5_link_control() to send a SYNC message.
But h5_link_control() only enqueues the packet and requires the caller
to call hci_uart_tx_wakeup(). Thus, after H5_SYNC_TIMEOUT ran out
(100ms), h5_timed_event() would be called and, realizing that the state
was still H5_UNINITIALIZED, it would re-enqueue the SYNC and call
hci_uart_tx_wakeup(). Consequently, two SYNC packets would be sent and
initialization would unnecessarily wait for 100ms.

The naive solution of calling hci_uart_tx_wakeup() in h5_open() does not
work because it will only schedule tx work if the HCI_PROTO_READY bit is
set and hci_serdev only sets it after h5_open() returns. This patch
removes the extraneous SYNC being enqueued and makes h5_timed_event()
wake up on the next jiffy.

Signed-off-by: Javier Nieto <jgnieto@cs.stanford.edu>
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>

diff --git a/drivers/bluetooth/hci_h5.c b/drivers/bluetooth/hci_h5.c
index d0d4420c1a0f9afa749e6934fc85343bb3220ac1..863ee93dd8a8d97bfe959f3415f37093c2b9f369 100644 (file)
--- a/drivers/bluetooth/hci_h5.c
+++ b/drivers/bluetooth/hci_h5.c
@@ -213,7 +213,6 @@ static void h5_peer_reset(struct hci_uart *hu)
 static int h5_open(struct hci_uart *hu)
 {
        struct h5 *h5;
-       const unsigned char sync[] = { 0x01, 0x7e };
 
        BT_DBG("hu %p", hu);
 
@@ -243,9 +242,11 @@ static int h5_open(struct hci_uart *hu)
 
        set_bit(HCI_UART_INIT_PENDING, &hu->hdev_flags);
 
-       /* Send initial sync request */
-       h5_link_control(hu, sync, sizeof(sync));
-       mod_timer(&h5->timer, jiffies + H5_SYNC_TIMEOUT);
+       /*
+        * Wait one jiffy because the UART layer won't set HCI_UART_PROTO_READY,
+        * which allows us to send link packets, until this function returns.
+        */
+       mod_timer(&h5->timer, jiffies + 1);
 
        return 0;
 }