diff --git a/drivers/media/usb/dvb-usb-v2/az6007.c b/drivers/media/usb/dvb-usb-v2/az6007.c
index 65ef045b74ca..86ee62fd5f4f 100644
--- a/drivers/media/usb/dvb-usb-v2/az6007.c
+++ b/drivers/media/usb/dvb-usb-v2/az6007.c
@@ -97,19 +97,30 @@ static struct mt2063_config az6007_mt2063_config = {
 	.refclock = 36125000,
 };
 
-static int __az6007_read(struct usb_device *udev, u8 req, u16 value,
-			    u16 index, u8 *b, int blen)
+static int __az6007_read(struct dvb_usb_device *d, struct az6007_device_state *st,
+			    u8 req, u16 value, u16 index, u8 *b, int blen)
 {
 	int ret;
 
-	ret = usb_control_msg(udev,
-			      usb_rcvctrlpipe(udev, 0),
+	if (mutex_lock_interruptible(&d->usb_mutex) < 0)
+		return -EAGAIN;
+
+	if (blen > sizeof(st->data)) {
+		pr_err("az6007: tried to read %d bytes, but I2C max size is %lu bytes\n",
+		       blen, sizeof(st->data));
+		ret = -EOPNOTSUPP;
+		goto end_unlock;
+	}
+
+	ret = usb_control_msg(d->udev,
+			      usb_rcvctrlpipe(d->udev, 0),
 			      req,
 			      USB_TYPE_VENDOR | USB_DIR_IN,
 			      value, index, b, blen, 5000);
 	if (ret < 0) {
 		pr_warn("usb read operation failed. (%d)\n", ret);
-		return -EIO;
+		ret = -EIO;
+		goto end_unlock;
 	}
 
 	if (az6007_xfer_debug) {
@@ -119,30 +130,42 @@ static int __az6007_read(struct usb_device *udev, u8 req, u16 value,
 				     DUMP_PREFIX_NONE, b, blen);
 	}
 
+end_unlock:
+	mutex_unlock(&d->usb_mutex);
 	return ret;
 }
 
 static int az6007_read(struct dvb_usb_device *d, u8 req, u16 value,
 			    u16 index, u8 *b, int blen)
 {
-	struct az6007_device_state *st = d->priv;
+	struct az6007_device_state *st = d_to_priv(d);
 	int ret;
 
 	if (mutex_lock_interruptible(&st->mutex) < 0)
 		return -EAGAIN;
 
-	ret = __az6007_read(d->udev, req, value, index, b, blen);
+	ret = __az6007_read(d, st, req, value, index, b, blen);
 
 	mutex_unlock(&st->mutex);
 
 	return ret;
 }
 
-static int __az6007_write(struct usb_device *udev, u8 req, u16 value,
-			     u16 index, u8 *b, int blen)
+static int __az6007_write(struct dvb_usb_device *d, struct az6007_device_state *st,
+			    u8 req, u16 value, u16 index, u8 *b, int blen)
 {
 	int ret;
 
+	if (mutex_lock_interruptible(&d->usb_mutex) < 0)
+		return -EAGAIN;
+
+	if (blen > sizeof(st->data) - 1) {
+		pr_err("az6007: tried to write %d bytes, but I2C max size is %lu bytes\n",
+		       blen, sizeof(st->data));
+		ret = -EOPNOTSUPP;
+		goto end_unlock;
+	}
+
 	if (az6007_xfer_debug) {
 		printk(KERN_DEBUG "az6007: OUT req: %02x, value: %04x, index: %04x\n",
 		       req, value, index);
@@ -150,35 +173,33 @@ static int __az6007_write(struct usb_device *udev, u8 req, u16 value,
 				     DUMP_PREFIX_NONE, b, blen);
 	}
 
-	if (blen > 64) {
-		pr_err("az6007: tried to write %d bytes, but I2C max size is 64 bytes\n",
-		       blen);
-		return -EOPNOTSUPP;
-	}
-
-	ret = usb_control_msg(udev,
-			      usb_sndctrlpipe(udev, 0),
+	ret = usb_control_msg(d->udev,
+			      usb_sndctrlpipe(d->udev, 0),
 			      req,
 			      USB_TYPE_VENDOR | USB_DIR_OUT,
 			      value, index, b, blen, 5000);
 	if (ret != blen) {
 		pr_err("usb write operation failed. (%d)\n", ret);
-		return -EIO;
+		ret = -EIO;
+		goto end_unlock;
 	}
 
-	return 0;
+	ret = 0;
+end_unlock:
+	mutex_unlock(&d->usb_mutex);
+	return ret;
 }
 
 static int az6007_write(struct dvb_usb_device *d, u8 req, u16 value,
 			    u16 index, u8 *b, int blen)
 {
-	struct az6007_device_state *st = d->priv;
+	struct az6007_device_state *st = d_to_priv(d);
 	int ret;
 
 	if (mutex_lock_interruptible(&st->mutex) < 0)
 		return -EAGAIN;
 
-	ret = __az6007_write(d->udev, req, value, index, b, blen);
+	ret = __az6007_write(d, st, req, value, index, b, blen);
 
 	mutex_unlock(&st->mutex);
 
@@ -752,8 +773,12 @@ static int az6007_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[],
 	int length;
 	u8 req, addr;
 
-	if (mutex_lock_interruptible(&st->mutex) < 0)
+	if (mutex_lock_interruptible(&d->i2c_mutex) < 0)
+		return -EAGAIN;
+	if (mutex_lock_interruptible(&st->mutex) < 0) {
+		mutex_unlock(&d->i2c_mutex);
 		return -EAGAIN;
+	}
 
 	for (i = 0; i < num; i++) {
 		addr = msgs[i].addr << 1;
@@ -775,13 +800,12 @@ static int az6007_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[],
 			value = addr | (1 << 8);
 			length = 6 + msgs[i + 1].len;
 			len = msgs[i + 1].len;
-			ret = __az6007_read(d->udev, req, value, index,
+			ret = __az6007_read(d, st, req, value, index,
 					    st->data, length);
-			if (ret >= len) {
+			if (ret >= len + 5) {
 				for (j = 0; j < len; j++)
 					msgs[i + 1].buf[j] = st->data[j + 5];
-			} else
-				ret = -EIO;
+			}
 			i++;
 		} else if (!(msgs[i].flags & I2C_M_RD)) {
 			/* write bytes */
@@ -797,10 +821,8 @@ static int az6007_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[],
 			value = addr | (1 << 8);
 			length = msgs[i].len - 1;
 			len = msgs[i].len - 1;
-			for (j = 0; j < len; j++)
-				st->data[j] = msgs[i].buf[j + 1];
-			ret =  __az6007_write(d->udev, req, value, index,
-					      st->data, length);
+			ret = __az6007_write(d, st, req, value, index,
+					      &msgs[i].buf[1], length);
 		} else {
 			/* read bytes */
 			if (az6007_xfer_debug)
@@ -815,16 +837,19 @@ static int az6007_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[],
 			value = addr;
 			length = msgs[i].len + 6;
 			len = msgs[i].len;
-			ret = __az6007_read(d->udev, req, value, index,
+			ret = __az6007_read(d, st, req, value, index,
 					    st->data, length);
-			for (j = 0; j < len; j++)
-				msgs[i].buf[j] = st->data[j + 5];
+			if (ret >= len + 5) {
+				for (j = 0; j < len; j++)
+					msgs[i].buf[j] = st->data[j + 5];
+			}
 		}
 		if (ret < 0)
 			goto err;
 	}
 err:
 	mutex_unlock(&st->mutex);
+	mutex_unlock(&d->i2c_mutex);
 
 	if (ret < 0) {
 		pr_info("%s ERROR: %i\n", __func__, ret);
@@ -845,6 +870,7 @@ static const struct i2c_algorithm az6007_i2c_algo = {
 
 static int az6007_identify_state(struct dvb_usb_device *d, const char **name)
 {
+	struct az6007_device_state *state = d_to_priv(d);
 	int ret;
 	u8 *mac;
 
@@ -855,7 +881,7 @@ static int az6007_identify_state(struct dvb_usb_device *d, const char **name)
 		return -ENOMEM;
 
 	/* Try to read the mac address */
-	ret = __az6007_read(d->udev, AZ6007_READ_DATA, 6, 0, mac, 6);
+	ret = __az6007_read(d, state, AZ6007_READ_DATA, 6, 0, mac, 6);
 	if (ret == 6)
 		ret = WARM;
 	else
@@ -864,9 +890,9 @@ static int az6007_identify_state(struct dvb_usb_device *d, const char **name)
 	kfree(mac);
 
 	if (ret == COLD) {
-		__az6007_write(d->udev, 0x09, 1, 0, NULL, 0);
-		__az6007_write(d->udev, 0x00, 0, 0, NULL, 0);
-		__az6007_write(d->udev, 0x00, 0, 0, NULL, 0);
+		__az6007_write(d, state, 0x09, 1, 0, NULL, 0);
+		__az6007_write(d, state, 0x00, 0, 0, NULL, 0);
+		__az6007_write(d, state, 0x00, 0, 0, NULL, 0);
 	}
 
 	pr_debug("Device is on %s state\n",