From 685f5286bfe7081ac88ca487e7fca79bcf6f3262 Mon Sep 17 00:00:00 2001
From: Felix Fietkau <nbd@openwrt.org>
Date: Sat, 22 Sep 2012 00:34:53 +0000
Subject: [PATCH] cns3xxx: fix ethernet driver tx completion and queue
 stop/start

SVN-Revision: 33504
---
 .../430-ethernet_fix_tx_completion.patch      | 110 ++++++++++++++++++
 1 file changed, 110 insertions(+)
 create mode 100644 target/linux/cns3xxx/patches-3.3/430-ethernet_fix_tx_completion.patch

diff --git a/target/linux/cns3xxx/patches-3.3/430-ethernet_fix_tx_completion.patch b/target/linux/cns3xxx/patches-3.3/430-ethernet_fix_tx_completion.patch
new file mode 100644
index 0000000000..9a16c99f8f
--- /dev/null
+++ b/target/linux/cns3xxx/patches-3.3/430-ethernet_fix_tx_completion.patch
@@ -0,0 +1,110 @@
+--- a/drivers/net/ethernet/cavium/cns3xxx_eth.c
++++ b/drivers/net/ethernet/cavium/cns3xxx_eth.c
+@@ -28,6 +28,7 @@
+ 
+ #define RX_DESCS 128
+ #define TX_DESCS 128
++#define TX_DESC_RESERVE	20
+ 
+ #define RX_POOL_ALLOC_SIZE (sizeof(struct rx_desc) * RX_DESCS)
+ #define TX_POOL_ALLOC_SIZE (sizeof(struct tx_desc) * TX_DESCS)
+@@ -266,6 +267,7 @@ struct _tx_ring {
+ 	u32 cur_index;
+ 	int num_used;
+ 	int num_count;
++	bool stopped;
+ };
+ 
+ struct _rx_ring {
+@@ -546,7 +548,34 @@ out:
+ 	rx_ring->alloc_index = i;
+ }
+ 
+-static void clear_tx_desc(struct sw *sw)
++static void eth_check_num_used(struct _tx_ring *tx_ring)
++{
++	bool stop = false;
++	int i;
++
++	if (tx_ring->num_used >= TX_DESCS - TX_DESC_RESERVE)
++		stop = true;
++
++	if (tx_ring->stopped == stop)
++		return;
++
++	tx_ring->stopped = stop;
++	for (i = 0; i < 4; i++) {
++		struct port *port = switch_port_tab[i];
++		struct net_device *dev;
++
++		if (!port)
++			continue;
++
++		dev = port->netdev;
++		if (stop)
++			netif_stop_queue(dev);
++		else
++			netif_wake_queue(dev);
++	}
++}
++
++static void eth_complete_tx(struct sw *sw)
+ {
+ 	struct _tx_ring *tx_ring = sw->tx_ring;
+ 	struct tx_desc *desc;
+@@ -555,9 +584,6 @@ static void clear_tx_desc(struct sw *sw)
+ 	int num_used = tx_ring->num_used;
+ 	struct sk_buff *skb;
+ 
+-	if (num_used < (TX_DESCS >> 1))
+-		return;
+-
+ 	index = tx_ring->free_index;
+ 	desc = &(tx_ring)->desc[index];
+ 	for (i = 0; i < num_used; i++) {
+@@ -580,6 +606,7 @@ static void clear_tx_desc(struct sw *sw)
+ 	}
+ 	tx_ring->free_index = index;
+ 	tx_ring->num_used -= i;
++	eth_check_num_used(tx_ring);
+ }
+ 
+ static int eth_poll(struct napi_struct *napi, int budget)
+@@ -688,6 +715,10 @@ static int eth_poll(struct napi_struct *
+ 
+ 	enable_rx_dma(sw);
+ 
++	spin_lock_bh(&tx_lock);
++	eth_complete_tx(sw);
++	spin_unlock_bh(&tx_lock);
++
+ 	return received;
+ }
+ 
+@@ -732,21 +763,19 @@ static int eth_xmit(struct sk_buff *skb,
+ 	skb_walk_frags(skb, skb1)
+ 		nr_desc++;
+ 
+-	spin_lock(&tx_lock);
++	spin_lock_bh(&tx_lock);
+ 
++	eth_complete_tx(sw);
+ 	if ((tx_ring->num_used + nr_desc + 1) >= TX_DESCS) {
+-		clear_tx_desc(sw);
+-		if ((tx_ring->num_used + nr_desc + 1) >= TX_DESCS) {
+-			spin_unlock(&tx_lock);
+-			return NETDEV_TX_BUSY;
+-		}
++		spin_unlock_bh(&tx_lock);
++		return NETDEV_TX_BUSY;
+ 	}
+ 
+ 	index = index0 = tx_ring->cur_index;
+ 	index_last = (index0 + nr_desc) % TX_DESCS;
+ 	tx_ring->cur_index = (index_last + 1) % TX_DESCS;
+ 
+-	spin_unlock(&tx_lock);
++	spin_unlock_bh(&tx_lock);
+ 
+ 	config0 = FORCE_ROUTE;
+ 	if (skb->ip_summed == CHECKSUM_PARTIAL)
-- 
2.30.2