Update Linux to v5.4.148

Sourced from [1]

[1] https://cdn.kernel.org/pub/linux/kernel/v5.x/linux-5.4.148.tar.gz

Change-Id: Ib3d26c5ba9b022e2e03533005c4fed4d7c30b61b
Signed-off-by: Olivier Deprez <olivier.deprez@arm.com>
diff --git a/drivers/usb/serial/keyspan_pda.c b/drivers/usb/serial/keyspan_pda.c
index bf988f7..5dd228d 100644
--- a/drivers/usb/serial/keyspan_pda.c
+++ b/drivers/usb/serial/keyspan_pda.c
@@ -40,11 +40,12 @@
 #define DRIVER_AUTHOR "Brian Warner <warner@lothar.com>"
 #define DRIVER_DESC "USB Keyspan PDA Converter driver"
 
+#define KEYSPAN_TX_THRESHOLD	16
+
 struct keyspan_pda_private {
 	int			tx_room;
 	int			tx_throttled;
-	struct work_struct			wakeup_work;
-	struct work_struct			unthrottle_work;
+	struct work_struct	unthrottle_work;
 	struct usb_serial	*serial;
 	struct usb_serial_port	*port;
 };
@@ -97,15 +98,6 @@
 };
 #endif
 
-static void keyspan_pda_wakeup_write(struct work_struct *work)
-{
-	struct keyspan_pda_private *priv =
-		container_of(work, struct keyspan_pda_private, wakeup_work);
-	struct usb_serial_port *port = priv->port;
-
-	tty_port_tty_wakeup(&port->port);
-}
-
 static void keyspan_pda_request_unthrottle(struct work_struct *work)
 {
 	struct keyspan_pda_private *priv =
@@ -120,7 +112,7 @@
 				 7, /* request_unthrottle */
 				 USB_TYPE_VENDOR | USB_RECIP_INTERFACE
 				 | USB_DIR_OUT,
-				 16, /* value: threshold */
+				 KEYSPAN_TX_THRESHOLD,
 				 0, /* index */
 				 NULL,
 				 0,
@@ -139,6 +131,8 @@
 	int retval;
 	int status = urb->status;
 	struct keyspan_pda_private *priv;
+	unsigned long flags;
+
 	priv = usb_get_serial_port_data(port);
 
 	switch (status) {
@@ -172,18 +166,21 @@
 		break;
 	case 1:
 		/* status interrupt */
-		if (len < 3) {
+		if (len < 2) {
 			dev_warn(&port->dev, "short interrupt message received\n");
 			break;
 		}
-		dev_dbg(&port->dev, "rx int, d1=%d, d2=%d\n", data[1], data[2]);
+		dev_dbg(&port->dev, "rx int, d1=%d\n", data[1]);
 		switch (data[1]) {
 		case 1: /* modemline change */
 			break;
 		case 2: /* tx unthrottle interrupt */
+			spin_lock_irqsave(&port->lock, flags);
 			priv->tx_throttled = 0;
+			priv->tx_room = max(priv->tx_room, KEYSPAN_TX_THRESHOLD);
+			spin_unlock_irqrestore(&port->lock, flags);
 			/* queue up a wakeup at scheduler time */
-			schedule_work(&priv->wakeup_work);
+			usb_serial_port_softint(port);
 			break;
 		default:
 			break;
@@ -443,6 +440,7 @@
 	int request_unthrottle = 0;
 	int rc = 0;
 	struct keyspan_pda_private *priv;
+	unsigned long flags;
 
 	priv = usb_get_serial_port_data(port);
 	/* guess how much room is left in the device's ring buffer, and if we
@@ -462,13 +460,13 @@
 	   the TX urb is in-flight (wait until it completes)
 	   the device is full (wait until it says there is room)
 	*/
-	spin_lock_bh(&port->lock);
+	spin_lock_irqsave(&port->lock, flags);
 	if (!test_bit(0, &port->write_urbs_free) || priv->tx_throttled) {
-		spin_unlock_bh(&port->lock);
+		spin_unlock_irqrestore(&port->lock, flags);
 		return 0;
 	}
 	clear_bit(0, &port->write_urbs_free);
-	spin_unlock_bh(&port->lock);
+	spin_unlock_irqrestore(&port->lock, flags);
 
 	/* At this point the URB is in our control, nobody else can submit it
 	   again (the only sudden transition was the one from EINPROGRESS to
@@ -514,7 +512,8 @@
 			goto exit;
 		}
 	}
-	if (count > priv->tx_room) {
+
+	if (count >= priv->tx_room) {
 		/* we're about to completely fill the Tx buffer, so
 		   we'll be throttled afterwards. */
 		count = priv->tx_room;
@@ -547,7 +546,7 @@
 
 	rc = count;
 exit:
-	if (rc < 0)
+	if (rc <= 0)
 		set_bit(0, &port->write_urbs_free);
 	return rc;
 }
@@ -556,27 +555,28 @@
 static void keyspan_pda_write_bulk_callback(struct urb *urb)
 {
 	struct usb_serial_port *port = urb->context;
-	struct keyspan_pda_private *priv;
 
 	set_bit(0, &port->write_urbs_free);
-	priv = usb_get_serial_port_data(port);
 
 	/* queue up a wakeup at scheduler time */
-	schedule_work(&priv->wakeup_work);
+	usb_serial_port_softint(port);
 }
 
 
 static int keyspan_pda_write_room(struct tty_struct *tty)
 {
 	struct usb_serial_port *port = tty->driver_data;
-	struct keyspan_pda_private *priv;
-	priv = usb_get_serial_port_data(port);
-	/* used by n_tty.c for processing of tabs and such. Giving it our
-	   conservative guess is probably good enough, but needs testing by
-	   running a console through the device. */
-	return priv->tx_room;
-}
+	struct keyspan_pda_private *priv = usb_get_serial_port_data(port);
+	unsigned long flags;
+	int room = 0;
 
+	spin_lock_irqsave(&port->lock, flags);
+	if (test_bit(0, &port->write_urbs_free) && !priv->tx_throttled)
+		room = priv->tx_room;
+	spin_unlock_irqrestore(&port->lock, flags);
+
+	return room;
+}
 
 static int keyspan_pda_chars_in_buffer(struct tty_struct *tty)
 {
@@ -656,8 +656,12 @@
 }
 static void keyspan_pda_close(struct usb_serial_port *port)
 {
+	struct keyspan_pda_private *priv = usb_get_serial_port_data(port);
+
 	usb_kill_urb(port->write_urb);
 	usb_kill_urb(port->interrupt_in_urb);
+
+	cancel_work_sync(&priv->unthrottle_work);
 }
 
 
@@ -715,7 +719,6 @@
 	if (!priv)
 		return -ENOMEM;
 
-	INIT_WORK(&priv->wakeup_work, keyspan_pda_wakeup_write);
 	INIT_WORK(&priv->unthrottle_work, keyspan_pda_request_unthrottle);
 	priv->serial = port->serial;
 	priv->port = port;