linux-kernel - [PATCH 5/9] net: mediatek: fix stop and wakeup of queue

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Message-Id: <1460051876-53135-5-git-send-email-blogic@openwrt.org>
Date:	Thu,  7 Apr 2016 19:57:52 +0200
From:	John Crispin <blogic@...nwrt.org>
To:	"David S. Miller" <davem@...emloft.net>
Cc:	Felix Fietkau <nbd@...nwrt.org>,
	Matthias Brugger <matthias.bgg@...il.com>,
	Sean Wang (王志亘) 
	<sean.wang@...iatek.com>, netdev@...r.kernel.org,
	linux-mediatek@...ts.infradead.org, linux-kernel@...r.kernel.org,
	John Crispin <blogic@...nwrt.org>
Subject: [PATCH 5/9] net: mediatek: fix stop and wakeup of queue

The driver supports 2 MACs. Both run on the same DMA ring. If we go
above/below the TX rings threshold value, we always need to wake/stop
the queue of both devices. Not doing to can cause TX stalls and packet
drops on one of the devices.

Signed-off-by: John Crispin <blogic@...nwrt.org>
---
 drivers/net/ethernet/mediatek/mtk_eth_soc.c |   37 +++++++++++++++++++--------
 1 file changed, 27 insertions(+), 10 deletions(-)

diff --git a/drivers/net/ethernet/mediatek/mtk_eth_soc.c b/drivers/net/ethernet/mediatek/mtk_eth_soc.c
index a4982e4..4ebc42e 100644
--- a/drivers/net/ethernet/mediatek/mtk_eth_soc.c
+++ b/drivers/net/ethernet/mediatek/mtk_eth_soc.c
@@ -684,6 +684,28 @@ static inline int mtk_cal_txd_req(struct sk_buff *skb)
 	return nfrags;
 }
 
+static void mtk_wake_queue(struct mtk_eth *eth)
+{
+	int i;
+
+	for (i = 0; i < MTK_MAC_COUNT; i++) {
+		if (!eth->netdev[i])
+			continue;
+		netif_wake_queue(eth->netdev[i]);
+	}
+}
+
+static void mtk_stop_queue(struct mtk_eth *eth)
+{
+	int i;
+
+	for (i = 0; i < MTK_MAC_COUNT; i++) {
+		if (!eth->netdev[i])
+			continue;
+		netif_stop_queue(eth->netdev[i]);
+	}
+}
+
 static int mtk_start_xmit(struct sk_buff *skb, struct net_device *dev)
 {
 	struct mtk_mac *mac = netdev_priv(dev);
@@ -695,7 +717,7 @@ static int mtk_start_xmit(struct sk_buff *skb, struct net_device *dev)
 
 	tx_num = mtk_cal_txd_req(skb);
 	if (unlikely(atomic_read(&ring->free_count) <= tx_num)) {
-		netif_stop_queue(dev);
+		mtk_stop_queue(eth);
 		netif_err(eth, tx_queued, dev,
 			  "Tx Ring full when queue awake!\n");
 		return NETDEV_TX_BUSY;
@@ -720,10 +742,10 @@ static int mtk_start_xmit(struct sk_buff *skb, struct net_device *dev)
 		goto drop;
 
 	if (unlikely(atomic_read(&ring->free_count) <= ring->thresh)) {
-		netif_stop_queue(dev);
+		mtk_stop_queue(eth);
 		if (unlikely(atomic_read(&ring->free_count) >
 			     ring->thresh))
-			netif_wake_queue(dev);
+			mtk_wake_queue(eth);
 	}
 
 	return NETDEV_TX_OK;
@@ -897,13 +919,8 @@ static int mtk_poll_tx(struct mtk_eth *eth, int budget, bool *tx_again)
 	if (!total)
 		return 0;
 
-	for (i = 0; i < MTK_MAC_COUNT; i++) {
-		if (!eth->netdev[i] ||
-		    unlikely(!netif_queue_stopped(eth->netdev[i])))
-			continue;
-		if (atomic_read(&ring->free_count) > ring->thresh)
-			netif_wake_queue(eth->netdev[i]);
-	}
+	if (atomic_read(&ring->free_count) > ring->thresh)
+		mtk_wake_queue(eth);
 
 	return total;
 }
-- 
1.7.10.4