move patches to patches-2.6.36

[openwrt/openwrt.git] / target / linux / leon / patches-2.6.36 / 020-greth_optimize_gbit_tx_descriptor_handling.patch

diff --git a/target/linux/leon/patches-2.6.36/020-greth_optimize_gbit_tx_descriptor_handling.patch b/target/linux/leon/patches-2.6.36/020-greth_optimize_gbit_tx_descriptor_handling.patch
new file mode 100644 (file)
index 0000000..3a14eb7
--- /dev/null
+++ b/target/linux/leon/patches-2.6.36/020-greth_optimize_gbit_tx_descriptor_handling.patch
@@ -0,0 +1,61 @@
+From 544631281bed5cc37b8f2d3a99f44c9d4b97f9a8 Mon Sep 17 00:00:00 2001
+From: Daniel Hellstrom <daniel@gaisler.com>
+Date: Wed, 1 Dec 2010 10:07:12 +0100
+Subject: [PATCH] GRETH: GBit transmit descriptor handling optimization
+
+It is safe to enable all fragments before enabling the first descriptor,
+this way all descriptors don't have to be processed twice, added extra
+memory barrier.
+
+Signed-off-by: Daniel Hellstrom <daniel@gaisler.com>
+---
+ drivers/net/greth.c |   19 ++++++++++---------
+ 1 files changed, 10 insertions(+), 9 deletions(-)
+
+--- a/drivers/net/greth.c
++++ b/drivers/net/greth.c
+@@ -512,7 +512,7 @@ greth_start_xmit_gbit(struct sk_buff *sk
+               greth->tx_skbuff[curr_tx] = NULL;
+               bdp = greth->tx_bd_base + curr_tx;
+ 
+-              status = GRETH_TXBD_CSALL;
++              status = GRETH_TXBD_CSALL | GRETH_BD_EN;
+               status |= frag->size & GRETH_BD_LEN;
+ 
+               /* Wrap around descriptor ring */
+@@ -549,26 +549,27 @@ greth_start_xmit_gbit(struct sk_buff *sk
+ 
+       wmb();
+ 
+-      /* Enable the descriptors that we configured ...  */
+-      for (i = 0; i < nr_frags + 1; i++) {
+-              bdp = greth->tx_bd_base + greth->tx_next;
+-              greth_write_bd(&bdp->stat, greth_read_bd(&bdp->stat) | GRETH_BD_EN);
+-              greth->tx_next = NEXT_TX(greth->tx_next);
+-              greth->tx_free--;
+-      }
++      /* Enable the descriptor chain by enabling the first descriptor */
++      bdp = greth->tx_bd_base + greth->tx_next;
++      greth_write_bd(&bdp->stat, greth_read_bd(&bdp->stat) | GRETH_BD_EN);
++      greth->tx_next = curr_tx;
++      greth->tx_free -= nr_frags + 1;
++
++      wmb();
+ 
+       greth_enable_tx(greth);
+ 
+       return NETDEV_TX_OK;
+ 
+ frag_map_error:
+-      /* Unmap SKB mappings that succeeded */
++      /* Unmap SKB mappings that succeeded and disable descriptor */
+       for (i = 0; greth->tx_next + i != curr_tx; i++) {
+               bdp = greth->tx_bd_base + greth->tx_next + i;
+               dma_unmap_single(greth->dev,
+                                greth_read_bd(&bdp->addr),
+                                greth_read_bd(&bdp->stat) & GRETH_BD_LEN,
+                                DMA_TO_DEVICE);
++              greth_write_bd(&bdp->stat, 0);
+       }
+ map_error:
+       if (net_ratelimit())