netdev: bfin_mac: disable hardware checksum if writeback cache is enabled

With writeback caches, corrupted RX packets will be sent up the stack
without any error markings.

Signed-off-by: Sonic Zhang <sonic.zhang@analog.com>
Signed-off-by: Mike Frysinger <vapier@gentoo.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/bfin_mac.h

@@ -17,7 +17,14 @@
 #include <linux/etherdevice.h>
 #include <linux/bfin_mac.h>
 
+/*
+ * Disable hardware checksum for bug #5600 if writeback cache is
+ * enabled. Otherwize, corrupted RX packet will be sent up stack
+ * without error mark.
+ */
+#ifndef CONFIG_BFIN_EXTMEM_WRITEBACK
 #define BFIN_MAC_CSUM_OFFLOAD
+#endif
 
 #define TX_RECLAIM_JIFFIES (HZ / 5)