Bluetooth: hci_qca: Disable IBS state machine and flush Tx buffer

During hci down we observed IBS sleep commands are queued in the Tx
buffer and hci_uart_write_work is sending data to the chip which is
not required as the chip is powered off. This patch will disable IBS
and flush the Tx buffer before we turn off the chip.
Signed-off-by: Balakrishna Godavarthi <bgodavar@codeaurora.org>
Reviewed-by: Matthias Kaehlcke <mka@chromium.org>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

drivers/bluetooth/hci_qca.c

@@ -771,16 +771,17 @@ static int qca_enqueue(struct hci_uart *hu, struct sk_buff *skb)
 	/* Prepend skb with frame type */
 	memcpy(skb_push(skb, 1), &hci_skb_pkt_type(skb), 1);
 
+	spin_lock_irqsave(&qca->hci_ibs_lock, flags);
+
 	/* Don't go to sleep in middle of patch download or
 	 * Out-Of-Band(GPIOs control) sleep is selected.
 	 */
 	if (!test_bit(STATE_IN_BAND_SLEEP_ENABLED, &qca->flags)) {
 		skb_queue_tail(&qca->txq, skb);
+		spin_unlock_irqrestore(&qca->hci_ibs_lock, flags);
 		return 0;
 	}
 
-	spin_lock_irqsave(&qca->hci_ibs_lock, flags);
-
 	/* Act according to current state */
 	switch (qca->tx_ibs_state) {
 	case HCI_IBS_TX_AWAKE:
@@ -1275,6 +1276,18 @@ static const struct qca_vreg_data qca_soc_data = {
 
 static void qca_power_shutdown(struct hci_uart *hu)
 {
+	struct qca_data *qca = hu->priv;
+	unsigned long flags;
+
+	/* From this point we go into power off state. But serial port is
+	 * still open, stop queueing the IBS data and flush all the buffered
+	 * data in skb's.
+	 */
+	spin_lock_irqsave(&qca->hci_ibs_lock, flags);
+	clear_bit(STATE_IN_BAND_SLEEP_ENABLED, &qca->flags);
+	qca_flush(hu);
+	spin_unlock_irqrestore(&qca->hci_ibs_lock, flags);
+
 	host_set_baudrate(hu, 2400);
 	qca_send_power_pulse(hu, QCA_WCN3990_POWEROFF_PULSE);
 	qca_power_setup(hu, false);