RE: [PATCH v4 5/6] net: fec: Add Scatter/gather support

From: Fugang Duan

Add Scatter/gather support for FEC.
This feature allows to improve outbound throughput performance.

...

+static int fec_enet_get_free_txdesc_num(struct fec_enet_private *fep)
+{
+	int entries;
+
+	entries = ((const char *)fep->dirty_tx -
+			(const char *)fep->cur_tx) / fep->bufdesc_size;
+
+	return (fep->cur_tx >= fep->dirty_tx) ?
+		entries += fep->tx_ring_size : entries;
+}

That is a strange return statement - why += ??

You could also check the sign of 'entries'.
Say:
	return entries > 0 ? entries : entries + fep->tx_ring_size;

Actually do you ever use the last entry?
If you do then the full and empty conditions are not separated.

	David