commit 23a598f719811fbb1807ed377382fef019b9b3cd
author Michal Simek <michal.simek@xilinx.com> Mon Aug 17 09:58:54 2015 +0200
committer Michal Simek <michal.simek@xilinx.com> Thu Nov 19 13:50:09 2015 +0100
tree 6c9672ce4e9421819077f6686a7530f7508830fa
parent 081dc2fa78e4a2760ffd713292da430e9290a662

net: zynq: Add dummy packet to fix packet duplication issue

Target is duplicating packets. IP prefetches another BD and process it
when the first one is sent. Adding one dummy BD to the chain fix the
problem with packet duplication.

Signed-off-by: Michal Simek <michal.simek@xilinx.com>
Acked-by: Joe Hershberger <joe.hershberger@ni.com>

drivers/net/zynq_gem.c

diff --git a/drivers/net/zynq_gem.c b/drivers/net/zynq_gem.c
index 946dc1b..1b5b6fd 100644
--- a/drivers/net/zynq_gem.c
+++ b/drivers/net/zynq_gem.c
@@ -46,6 +46,7 @@
 /* Wrap bit, last descriptor */
 #define ZYNQ_GEM_TXBUF_WRAP_MASK	0x40000000
 #define ZYNQ_GEM_TXBUF_LAST_MASK	0x00008000 /* Last buffer */
+#define ZYNQ_GEM_TXBUF_USED_MASK	0x80000000 /* Used by Hw */
 
 #define ZYNQ_GEM_NWCTRL_TXEN_MASK	0x00000008 /* Enable transmit */
 #define ZYNQ_GEM_NWCTRL_RXEN_MASK	0x00000004 /* Enable receive */
@@ -405,14 +406,19 @@
 	u32 addr, size;
 	struct zynq_gem_priv *priv = dev->priv;
 	struct zynq_gem_regs *regs = (struct zynq_gem_regs *)dev->iobase;
+	struct emac_bd *current_bd = &priv->tx_bd[1];
 
 	/* Setup Tx BD */
 	memset(priv->tx_bd, 0, sizeof(struct emac_bd));
 
 	priv->tx_bd->addr = (ulong)ptr;
 	priv->tx_bd->status = (len & ZYNQ_GEM_TXBUF_FRMLEN_MASK) |
-			       ZYNQ_GEM_TXBUF_LAST_MASK |
-			       ZYNQ_GEM_TXBUF_WRAP_MASK;
+			       ZYNQ_GEM_TXBUF_LAST_MASK;
+	/* Dummy descriptor to mark it as the last in descriptor chain */
+	current_bd->addr = 0x0;
+	current_bd->status = ZYNQ_GEM_TXBUF_WRAP_MASK |
+			     ZYNQ_GEM_TXBUF_LAST_MASK|
+			     ZYNQ_GEM_TXBUF_USED_MASK;
 
 	/* setup BD */
 	writel((ulong)priv->tx_bd, &regs->txqbase);