--- zzzz-none-000/linux-3.10.107/drivers/usb/class/cdc-wdm.c	2017-06-27 09:49:32.000000000 +0000
+++ scorpion-7490-727/linux-3.10.107/drivers/usb/class/cdc-wdm.c	2021-02-04 17:41:59.000000000 +0000
@@ -101,6 +101,7 @@
 	struct work_struct	rxwork;
 	int			werr;
 	int			rerr;
+	int                     resp_count;
 
 	struct list_head	device_list;
 	int			(*manage_power)(struct usb_interface *, int);
@@ -253,6 +254,10 @@
 			"NOTIFY_NETWORK_CONNECTION %s network",
 			dr->wValue ? "connected to" : "disconnected from");
 		goto exit;
+	case USB_CDC_NOTIFY_SPEED_CHANGE:
+		dev_dbg(&desc->intf->dev, "SPEED_CHANGE received (len %u)",
+			urb->actual_length);
+		goto exit;
 	default:
 		clear_bit(WDM_POLL_RUNNING, &desc->flags);
 		dev_err(&desc->intf->dev,
@@ -264,9 +269,9 @@
 	}
 
 	spin_lock(&desc->iuspin);
-	clear_bit(WDM_READ, &desc->flags);
 	responding = test_and_set_bit(WDM_RESPONDING, &desc->flags);
-	if (!responding && !test_bit(WDM_DISCONNECTING, &desc->flags)
+	if (!desc->resp_count++ && !responding
+		&& !test_bit(WDM_DISCONNECTING, &desc->flags)
 		&& !test_bit(WDM_SUSPENDING, &desc->flags)) {
 		rv = usb_submit_urb(desc->response, GFP_ATOMIC);
 		dev_dbg(&desc->intf->dev, "%s: usb_submit_urb %d",
@@ -336,7 +341,7 @@
 	desc->werr = 0;
 	spin_unlock_irq(&desc->iuspin);
 	if (we < 0)
-		return -EIO;
+		return usb_translate_errors(we);
 
 	buf = kmalloc(count, GFP_KERNEL);
 	if (!buf) {
@@ -346,30 +351,25 @@
 
 	r = copy_from_user(buf, buffer, count);
 	if (r > 0) {
-		kfree(buf);
 		rv = -EFAULT;
-		goto outnl;
+		goto out_free_mem;
 	}
 
 	/* concurrent writes and disconnect */
 	r = mutex_lock_interruptible(&desc->wlock);
 	rv = -ERESTARTSYS;
-	if (r) {
-		kfree(buf);
-		goto outnl;
-	}
+	if (r)
+		goto out_free_mem;
 
 	if (test_bit(WDM_DISCONNECTING, &desc->flags)) {
-		kfree(buf);
 		rv = -ENODEV;
-		goto outnp;
+		goto out_free_mem_lock;
 	}
 
 	r = usb_autopm_get_interface(desc->intf);
 	if (r < 0) {
-		kfree(buf);
 		rv = usb_translate_errors(r);
-		goto outnp;
+		goto out_free_mem_lock;
 	}
 
 	if (!(file->f_flags & O_NONBLOCK))
@@ -383,9 +383,8 @@
 		r = -EIO;
 
 	if (r < 0) {
-		kfree(buf);
 		rv = r;
-		goto out;
+		goto out_free_mem_pm;
 	}
 
 	req = desc->orq;
@@ -412,21 +411,60 @@
 
 	rv = usb_submit_urb(desc->command, GFP_KERNEL);
 	if (rv < 0) {
-		kfree(buf);
 		desc->outbuf = NULL;
 		clear_bit(WDM_IN_USE, &desc->flags);
 		dev_err(&desc->intf->dev, "Tx URB error: %d\n", rv);
 		rv = usb_translate_errors(rv);
+		goto out_free_mem_pm;
 	} else {
 		dev_dbg(&desc->intf->dev, "Tx URB has been submitted index=%d",
 			le16_to_cpu(req->wIndex));
 	}
-out:
+
 	usb_autopm_put_interface(desc->intf);
-outnp:
 	mutex_unlock(&desc->wlock);
 outnl:
 	return rv < 0 ? rv : count;
+
+out_free_mem_pm:
+	usb_autopm_put_interface(desc->intf);
+out_free_mem_lock:
+	mutex_unlock(&desc->wlock);
+out_free_mem:
+	kfree(buf);
+	return rv;
+}
+
+/*
+ * clear WDM_READ flag and possibly submit the read urb if resp_count
+ * is non-zero.
+ *
+ * Called with desc->iuspin locked
+ */
+static int clear_wdm_read_flag(struct wdm_device *desc)
+{
+	int rv = 0;
+
+	clear_bit(WDM_READ, &desc->flags);
+
+	/* submit read urb only if the device is waiting for it */
+	if (!desc->resp_count || !--desc->resp_count)
+		goto out;
+
+	set_bit(WDM_RESPONDING, &desc->flags);
+	spin_unlock_irq(&desc->iuspin);
+	rv = usb_submit_urb(desc->response, GFP_KERNEL);
+	spin_lock_irq(&desc->iuspin);
+	if (rv) {
+		dev_err(&desc->intf->dev,
+			"usb_submit_urb failed with result %d\n", rv);
+
+		/* make sure the next notification trigger a submit */
+		clear_bit(WDM_RESPONDING, &desc->flags);
+		desc->resp_count = 0;
+	}
+out:
+	return rv;
 }
 
 static ssize_t wdm_read
@@ -484,9 +522,9 @@
 		spin_lock_irq(&desc->iuspin);
 
 		if (desc->rerr) { /* read completed, error happened */
+			rv = usb_translate_errors(desc->rerr);
 			desc->rerr = 0;
 			spin_unlock_irq(&desc->iuspin);
-			rv = -EIO;
 			goto err;
 		}
 		/*
@@ -500,8 +538,10 @@
 
 		if (!desc->reslength) { /* zero length read */
 			dev_dbg(&desc->intf->dev, "%s: zero length - clearing WDM_READ\n", __func__);
-			clear_bit(WDM_READ, &desc->flags);
+			rv = clear_wdm_read_flag(desc);
 			spin_unlock_irq(&desc->iuspin);
+			if (rv < 0)
+				goto err;
 			goto retry;
 		}
 		cntr = desc->length;
@@ -524,10 +564,8 @@
 	desc->length -= cntr;
 	/* in case we had outstanding data */
 	if (!desc->length)
-		clear_bit(WDM_READ, &desc->flags);
-
+		clear_wdm_read_flag(desc);
 	spin_unlock_irq(&desc->iuspin);
-
 	rv = cntr;
 
 err:
@@ -637,6 +675,9 @@
 		if (!test_bit(WDM_DISCONNECTING, &desc->flags)) {
 			dev_dbg(&desc->intf->dev, "wdm_release: cleanup");
 			kill_urbs(desc);
+			spin_lock_irq(&desc->iuspin);
+			desc->resp_count = 0;
+			spin_unlock_irq(&desc->iuspin);
 			desc->manage_power(desc->intf, 0);
 		} else {
 			/* must avoid dev_printk here as desc->intf is invalid */