mwifiex: add support for Marvell USB8797 chipset

This patch supports Avastar 88W8797 chipset with USB interface.

The corresponding firmware image file is located at:
"mrvl/usb8797_uapsta.bin"

Signed-off-by: Amitkumar Karwar <akarwar@marvell.com>
Signed-off-by: Bing Zhao <bzhao@marvell.com>
Signed-off-by: Kiran Divekar <dkiran@marvell.com>
Signed-off-by: Frank Huang <frankh@marvell.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/drivers/net/wireless/mwifiex/util.c b/drivers/net/wireless/mwifiex/util.c
index 6b39997..2864c74 100644
--- a/drivers/net/wireless/mwifiex/util.c
+++ b/drivers/net/wireless/mwifiex/util.c
@@ -167,6 +167,28 @@
 	skb->dev = priv->netdev;
 	skb->protocol = eth_type_trans(skb, priv->netdev);
 	skb->ip_summed = CHECKSUM_NONE;
+
+	/* This is required only in case of 11n and USB as we alloc
+	 * a buffer of 4K only if its 11N (to be able to receive 4K
+	 * AMSDU packets). In case of SD we allocate buffers based
+	 * on the size of packet and hence this is not needed.
+	 *
+	 * Modifying the truesize here as our allocation for each
+	 * skb is 4K but we only receive 2K packets and this cause
+	 * the kernel to start dropping packets in case where
+	 * application has allocated buffer based on 2K size i.e.
+	 * if there a 64K packet received (in IP fragments and
+	 * application allocates 64K to receive this packet but
+	 * this packet would almost double up because we allocate
+	 * each 1.5K fragment in 4K and pass it up. As soon as the
+	 * 64K limit hits kernel will start to drop rest of the
+	 * fragments. Currently we fail the Filesndl-ht.scr script
+	 * for UDP, hence this fix
+	 */
+	if ((adapter->iface_type == MWIFIEX_USB) &&
+	    (skb->truesize > MWIFIEX_RX_DATA_BUF_SIZE))
+		skb->truesize += (skb->len - MWIFIEX_RX_DATA_BUF_SIZE);
+
 	priv->stats.rx_bytes += skb->len;
 	priv->stats.rx_packets++;
 	if (in_interrupt())