Bluetooth: Improve Three-wire UART configuration handling

The configuration request/response messages contain a configuration
field which contains the sliding window size (amount of unacked reliable
packets that can be pending). This patch makes sure that we configure
the correct size (minimum of local and remote values) and use it when
determining whether to send new packets or not.

Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
Signed-off-by: Gustavo Padovan <gustavo.padovan@collabora.co.uk>

drivers/bluetooth/hci_h5.c

@@ -33,7 +33,8 @@
 #define HCI_3WIRE_ACK_PKT	0
 #define HCI_3WIRE_LINK_PKT	15
 
-#define H5_TXWINSIZE	4
+/* Sliding window size */
+#define H5_TX_WIN_MAX		4
 
 #define H5_ACK_TIMEOUT	msecs_to_jiffies(250)
 #define H5_SYNC_TIMEOUT	msecs_to_jiffies(100)
@@ -74,6 +75,7 @@ struct h5 {
 	bool			tx_ack_req;	/* Pending ack to send */
 	u8			tx_seq;		/* Next seq number to send */
 	u8			tx_ack;		/* Next ack number to send */
+	u8			tx_win;		/* Sliding window size */
 
 	enum {
 		H5_UNINITIALIZED,
@@ -106,10 +108,20 @@ static void h5_link_control(struct hci_uart *hu, const void *data, size_t len)
 	skb_queue_tail(&h5->unrel, nskb);
 }
 
+static u8 h5_cfg_field(struct h5 *h5)
+{
+	u8 field = 0;
+
+	/* Sliding window size (first 3 bits) */
+	field |= (h5->tx_win & 7);
+
+	return field;
+}
+
 static void h5_timed_event(unsigned long arg)
 {
 	const unsigned char sync_req[] = { 0x01, 0x7e };
-	const unsigned char conf_req[] = { 0x03, 0xfc, 0x01 };
+	unsigned char conf_req[] = { 0x03, 0xfc, 0x01 };
 	struct hci_uart *hu = (struct hci_uart *) arg;
 	struct h5 *h5 = hu->priv;
 	struct sk_buff *skb;
@@ -120,8 +132,10 @@ static void h5_timed_event(unsigned long arg)
 	if (h5->state == H5_UNINITIALIZED)
 		h5_link_control(hu, sync_req, sizeof(sync_req));
 
-	if (h5->state == H5_INITIALIZED)
+	if (h5->state == H5_INITIALIZED) {
+		conf_req[2] = h5_cfg_field(h5);
 		h5_link_control(hu, conf_req, sizeof(conf_req));
+	}
 
 	if (h5->state != H5_ACTIVE) {
 		mod_timer(&h5->timer, jiffies + H5_SYNC_TIMEOUT);
@@ -171,6 +185,8 @@ static int h5_open(struct hci_uart *hu)
 	h5->timer.function = h5_timed_event;
 	h5->timer.data = (unsigned long) hu;
 
+	h5->tx_win = H5_TX_WIN_MAX;
+
 	set_bit(HCI_UART_INIT_PENDING, &hu->hdev_flags);
 
 	/* Send initial sync request */
@@ -242,8 +258,8 @@ static void h5_handle_internal_rx(struct hci_uart *hu)
 	struct h5 *h5 = hu->priv;
 	const unsigned char sync_req[] = { 0x01, 0x7e };
 	const unsigned char sync_rsp[] = { 0x02, 0x7d };
-	const unsigned char conf_req[] = { 0x03, 0xfc, 0x01 };
-	const unsigned char conf_rsp[] = { 0x04, 0x7b, 0x01 };
+	unsigned char conf_req[] = { 0x03, 0xfc, 0x01 };
+	const unsigned char conf_rsp[] = { 0x04, 0x7b };
 	const unsigned char wakeup_req[] = { 0x05, 0xfa };
 	const unsigned char woken_req[] = { 0x06, 0xf9 };
 	const unsigned char sleep_req[] = { 0x07, 0x78 };
@@ -258,6 +274,8 @@ static void h5_handle_internal_rx(struct hci_uart *hu)
 	if (H5_HDR_LEN(hdr) < 2)
 		return;
 
+	conf_req[2] = h5_cfg_field(h5);
+
 	if (memcmp(data, sync_req, 2) == 0) {
 		h5_link_control(hu, sync_rsp, 2);
 	} else if (memcmp(data, sync_rsp, 2) == 0) {
@@ -267,7 +285,9 @@ static void h5_handle_internal_rx(struct hci_uart *hu)
 		h5_link_control(hu, conf_rsp, 2);
 		h5_link_control(hu, conf_req, 3);
 	} else if (memcmp(data, conf_rsp, 2) == 0) {
-		BT_DBG("Three-wire init sequence complete");
+		if (H5_HDR_LEN(hdr) > 2)
+			h5->tx_win = (data[2] & 7);
+		BT_DBG("Three-wire init complete. tx_win %u", h5->tx_win);
 		h5->state = H5_ACTIVE;
 		hci_uart_init_ready(hu);
 		return;
@@ -663,7 +683,7 @@ static struct sk_buff *h5_dequeue(struct hci_uart *hu)
 
 	spin_lock_irqsave_nested(&h5->unack.lock, flags, SINGLE_DEPTH_NESTING);
 
-	if (h5->unack.qlen >= H5_TXWINSIZE)
+	if (h5->unack.qlen >= h5->tx_win)
 		goto unlock;
 
 	if ((skb = skb_dequeue(&h5->rel)) != NULL) {