1 files changed, 120 insertions, 54 deletions

diff --git a/drivers/usb/host/xhci-dbgtty.c b/drivers/usb/host/xhci-dbgtty.c
index b74e98e94393..d894081d8d15 100644
--- a/drivers/usb/host/xhci-dbgtty.c
+++ b/drivers/usb/host/xhci-dbgtty.c
@@ -25,16 +25,26 @@ static inline struct dbc_port *dbc_to_port(struct xhci_dbc *dbc)
 }
 
 static unsigned int
-dbc_send_packet(struct dbc_port *port, char *packet, unsigned int size)
+dbc_kfifo_to_req(struct dbc_port *port, char *packet)
 {
-	unsigned int		len;
-
-	len = kfifo_len(&port->write_fifo);
-	if (len < size)
-		size = len;
-	if (size != 0)
-		size = kfifo_out(&port->write_fifo, packet, size);
-	return size;
+	unsigned int	len;
+
+	len = kfifo_len(&port->port.xmit_fifo);
+
+	if (len == 0)
+		return 0;
+
+	len = min(len, DBC_MAX_PACKET);
+
+	if (port->tx_boundary)
+		len = min(port->tx_boundary, len);
+
+	len = kfifo_out(&port->port.xmit_fifo, packet, len);
+
+	if (port->tx_boundary)
+		port->tx_boundary -= len;
+
+	return len;
 }
 
 static int dbc_start_tx(struct dbc_port *port)
@@ -49,7 +59,7 @@ static int dbc_start_tx(struct dbc_port *port)
 
 	while (!list_empty(pool)) {
 		req = list_entry(pool->next, struct dbc_request, list_pool);
-		len = dbc_send_packet(port, req->buf, DBC_MAX_PACKET);
+		len = dbc_kfifo_to_req(port, req->buf);
 		if (len == 0)
 			break;
 		do_tty_wake = true;
@@ -100,15 +110,74 @@ static void dbc_start_rx(struct dbc_port *port)
 	}
 }
 
+/*
+ * Queue received data to tty buffer and push it.
+ *
+ * Returns nr of remaining bytes that didn't fit tty buffer, i.e. 0 if all
+ * bytes sucessfullt moved. In case of error returns negative errno.
+ * Call with lock held
+ */
+static int dbc_rx_push_buffer(struct dbc_port *port, struct dbc_request *req)
+{
+	char		*packet = req->buf;
+	unsigned int	n, size = req->actual;
+	int		count;
+
+	if (!req->actual)
+		return 0;
+
+	/* if n_read is set then request was partially moved to tty buffer */
+	n = port->n_read;
+	if (n) {
+		packet += n;
+		size -= n;
+	}
+
+	count = tty_insert_flip_string(&port->port, packet, size);
+	if (count)
+		tty_flip_buffer_push(&port->port);
+	if (count != size) {
+		port->n_read += count;
+		return size - count;
+	}
+
+	port->n_read = 0;
+	return 0;
+}
+
 static void
 dbc_read_complete(struct xhci_dbc *dbc, struct dbc_request *req)
 {
 	unsigned long		flags;
 	struct dbc_port		*port = dbc_to_port(dbc);
+	struct tty_struct	*tty;
+	int			untransferred;
+
+	tty = port->port.tty;
 
 	spin_lock_irqsave(&port->port_lock, flags);
+
+	/*
+	 * Only defer copyig data to tty buffer in case:
+	 * - !list_empty(&port->read_queue), there are older pending data
+	 * - tty is throttled
+	 * - failed to copy all data to buffer, defer remaining part
+	 */
+
+	if (list_empty(&port->read_queue) && tty && !tty_throttled(tty)) {
+		untransferred = dbc_rx_push_buffer(port, req);
+		if (untransferred == 0) {
+			list_add_tail(&req->list_pool, &port->read_pool);
+			if (req->status != -ESHUTDOWN)
+				dbc_start_rx(port);
+			goto out;
+		}
+	}
+
+	/* defer moving data from req to tty buffer to a tasklet */
 	list_add_tail(&req->list_pool, &port->read_queue);
 	tasklet_schedule(&port->push);
+out:
 	spin_unlock_irqrestore(&port->port_lock, flags);
 }
 
@@ -213,14 +282,32 @@ static ssize_t dbc_tty_write(struct tty_struct *tty, const u8 *buf,
 {
 	struct dbc_port		*port = tty->driver_data;
 	unsigned long		flags;
+	unsigned int		written = 0;
 
 	spin_lock_irqsave(&port->port_lock, flags);
-	if (count)
-		count = kfifo_in(&port->write_fifo, buf, count);
-	dbc_start_tx(port);
+
+	/*
+	 * Treat tty write as one usb transfer. Make sure the writes are turned
+	 * into TRB request having the same size boundaries as the tty writes.
+	 * Don't add data to kfifo before previous write is turned into TRBs
+	 */
+	if (port->tx_boundary) {
+		spin_unlock_irqrestore(&port->port_lock, flags);
+		return 0;
+	}
+
+	if (count) {
+		written = kfifo_in(&port->port.xmit_fifo, buf, count);
+
+		if (written == count)
+			port->tx_boundary = kfifo_len(&port->port.xmit_fifo);
+
+		dbc_start_tx(port);
+	}
+
 	spin_unlock_irqrestore(&port->port_lock, flags);
 
-	return count;
+	return written;
 }
 
 static int dbc_tty_put_char(struct tty_struct *tty, u8 ch)
@@ -230,7 +317,7 @@ static int dbc_tty_put_char(struct tty_struct *tty, u8 ch)
 	int			status;
 
 	spin_lock_irqsave(&port->port_lock, flags);
-	status = kfifo_put(&port->write_fifo, ch);
+	status = kfifo_put(&port->port.xmit_fifo, ch);
 	spin_unlock_irqrestore(&port->port_lock, flags);
 
 	return status;
@@ -253,7 +340,11 @@ static unsigned int dbc_tty_write_room(struct tty_struct *tty)
 	unsigned int		room;
 
 	spin_lock_irqsave(&port->port_lock, flags);
-	room = kfifo_avail(&port->write_fifo);
+	room = kfifo_avail(&port->port.xmit_fifo);
+
+	if (port->tx_boundary)
+		room = 0;
+
 	spin_unlock_irqrestore(&port->port_lock, flags);
 
 	return room;
@@ -266,7 +357,7 @@ static unsigned int dbc_tty_chars_in_buffer(struct tty_struct *tty)
 	unsigned int		chars;
 
 	spin_lock_irqsave(&port->port_lock, flags);
-	chars = kfifo_len(&port->write_fifo);
+	chars = kfifo_len(&port->port.xmit_fifo);
 	spin_unlock_irqrestore(&port->port_lock, flags);
 
 	return chars;
@@ -299,10 +390,10 @@ static void dbc_rx_push(struct tasklet_struct *t)
 	struct dbc_request	*req;
 	struct tty_struct	*tty;
 	unsigned long		flags;
-	bool			do_push = false;
 	bool			disconnect = false;
 	struct dbc_port		*port = from_tasklet(port, t, push);
 	struct list_head	*queue = &port->read_queue;
+	int			untransferred;
 
 	spin_lock_irqsave(&port->port_lock, flags);
 	tty = port->port.tty;
@@ -324,42 +415,15 @@ static void dbc_rx_push(struct tasklet_struct *t)
 			break;
 		}
 
-		if (req->actual) {
-			char		*packet = req->buf;
-			unsigned int	n, size = req->actual;
-			int		count;
-
-			n = port->n_read;
-			if (n) {
-				packet += n;
-				size -= n;
-			}
-
-			count = tty_insert_flip_string(&port->port, packet,
-						       size);
-			if (count)
-				do_push = true;
-			if (count != size) {
-				port->n_read += count;
-				break;
-			}
-			port->n_read = 0;
-		}
+		untransferred = dbc_rx_push_buffer(port, req);
+		if (untransferred > 0)
+			break;
 
-		list_move(&req->list_pool, &port->read_pool);
+		list_move_tail(&req->list_pool, &port->read_pool);
 	}
 
-	if (do_push)
-		tty_flip_buffer_push(&port->port);
-
-	if (!list_empty(queue) && tty) {
-		if (!tty_throttled(tty)) {
-			if (do_push)
-				tasklet_schedule(&port->push);
-			else
-				pr_warn("ttyDBC0: RX not scheduled?\n");
-		}
-	}
+	if (!list_empty(queue))
+		tasklet_schedule(&port->push);
 
 	if (!disconnect)
 		dbc_start_rx(port);
@@ -424,7 +488,8 @@ static int xhci_dbc_tty_register_device(struct xhci_dbc *dbc)
 		goto err_idr;
 	}
 
-	ret = kfifo_alloc(&port->write_fifo, DBC_WRITE_BUF_SIZE, GFP_KERNEL);
+	ret = kfifo_alloc(&port->port.xmit_fifo, DBC_WRITE_BUF_SIZE,
+			  GFP_KERNEL);
 	if (ret)
 		goto err_exit_port;
 
@@ -453,7 +518,7 @@ err_free_requests:
 	xhci_dbc_free_requests(&port->read_pool);
 	xhci_dbc_free_requests(&port->write_pool);
 err_free_fifo:
-	kfifo_free(&port->write_fifo);
+	kfifo_free(&port->port.xmit_fifo);
 err_exit_port:
 	idr_remove(&dbc_tty_minors, port->minor);
 err_idr:
@@ -478,7 +543,7 @@ static void xhci_dbc_tty_unregister_device(struct xhci_dbc *dbc)
 	idr_remove(&dbc_tty_minors, port->minor);
 	mutex_unlock(&dbc_tty_minors_lock);
 
-	kfifo_free(&port->write_fifo);
+	kfifo_free(&port->port.xmit_fifo);
 	xhci_dbc_free_requests(&port->read_pool);
 	xhci_dbc_free_requests(&port->read_queue);
 	xhci_dbc_free_requests(&port->write_pool);
@@ -552,6 +617,7 @@ int dbc_tty_init(void)
 	dbc_tty_driver->type = TTY_DRIVER_TYPE_SERIAL;
 	dbc_tty_driver->subtype = SERIAL_TYPE_NORMAL;
 	dbc_tty_driver->init_termios = tty_std_termios;
+	dbc_tty_driver->init_termios.c_lflag &= ~ECHO;
 	dbc_tty_driver->init_termios.c_cflag =
 			B9600 | CS8 | CREAD | HUPCL | CLOCAL;
 	dbc_tty_driver->init_termios.c_ispeed = 9600;