net: pegasus: Use the new usb control message API.

The old usb_control_msg() let the caller handle the error and also did not
account for partial reads.  Since these are now considered harmful, move the
driver over to usb_control_msg_recv/send() calls.

Added small note about why set_registers() can't be used to substitute
set_register().

Signed-off-by: Petko Manolov <petko.manolov@konsulko.com>
Acked-by: David S. Miller <davem@davemloft.net>
Link: https://lore.kernel.org/r/20200927124909.16380-2-petko.manolov@konsulko.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/net/usb/pegasus.c

@@ -124,62 +124,31 @@ static void async_ctrl_callback(struct urb *urb)
 
 static int get_registers(pegasus_t *pegasus, __u16 indx, __u16 size, void *data)
 {
-	u8 *buf;
-	int ret;
-
-	buf = kmalloc(size, GFP_NOIO);
-	if (!buf)
-		return -ENOMEM;
-
-	ret = usb_control_msg(pegasus->usb, usb_rcvctrlpipe(pegasus->usb, 0),
-			      PEGASUS_REQ_GET_REGS, PEGASUS_REQT_READ, 0,
-			      indx, buf, size, 1000);
-	if (ret < 0)
-		netif_dbg(pegasus, drv, pegasus->net,
-			  "%s returned %d\n", __func__, ret);
-	else if (ret <= size)
-		memcpy(data, buf, ret);
-	kfree(buf);
-	return ret;
+	return usb_control_msg_recv(pegasus->usb, 0, PEGASUS_REQ_GET_REGS,
+				   PEGASUS_REQT_READ, 0, indx, data, size,
+				   1000, GFP_NOIO);
 }
 
 static int set_registers(pegasus_t *pegasus, __u16 indx, __u16 size,
 			 const void *data)
 {
-	u8 *buf;
-	int ret;
-
-	buf = kmemdup(data, size, GFP_NOIO);
-	if (!buf)
-		return -ENOMEM;
-
-	ret = usb_control_msg(pegasus->usb, usb_sndctrlpipe(pegasus->usb, 0),
-			      PEGASUS_REQ_SET_REGS, PEGASUS_REQT_WRITE, 0,
-			      indx, buf, size, 100);
-	if (ret < 0)
-		netif_dbg(pegasus, drv, pegasus->net,
-			  "%s returned %d\n", __func__, ret);
-	kfree(buf);
-	return ret;
+	return usb_control_msg_send(pegasus->usb, 0, PEGASUS_REQ_SET_REGS,
+				    PEGASUS_REQT_WRITE, 0, indx, data, size,
+				    1000, GFP_NOIO);
 }
 
+/*
+ * There is only one way to write to a single ADM8511 register and this is via
+ * specific control request.  'data' is ignored by the device, but it is here to
+ * not break the API.
+ */
 static int set_register(pegasus_t *pegasus, __u16 indx, __u8 data)
 {
-	u8 *buf;
-	int ret;
-
-	buf = kmemdup(&data, 1, GFP_NOIO);
-	if (!buf)
-		return -ENOMEM;
+	void *buf = &data;
 
-	ret = usb_control_msg(pegasus->usb, usb_sndctrlpipe(pegasus->usb, 0),
-			      PEGASUS_REQ_SET_REG, PEGASUS_REQT_WRITE, data,
-			      indx, buf, 1, 1000);
-	if (ret < 0)
-		netif_dbg(pegasus, drv, pegasus->net,
-			  "%s returned %d\n", __func__, ret);
-	kfree(buf);
-	return ret;
+	return usb_control_msg_send(pegasus->usb, 0, PEGASUS_REQ_SET_REG,
+				    PEGASUS_REQT_WRITE, data, indx, buf, 1,
+				    1000, GFP_NOIO);
 }
 
 static int update_eth_regs_async(pegasus_t *pegasus)