linux-kernel - [PATCH net-next-2.6 v6 04/20] can: EG20T PCH: Add Tx Flow Control

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Message-ID: <4CF47B2C.4010507@dsn.okisemi.com>
Date:	Tue, 30 Nov 2010 13:18:52 +0900
From:	Tomoya MORINAGA <tomoya-linux@....okisemi.com>
To:	Wolfgang Grandegger <wg@...ndegger.com>,
	Wolfram Sang <w.sang@...gutronix.de>,
	Christian Pellegrin <chripell@...e.org>,
	Barry Song <21cnbao@...il.com>,
	Samuel Ortiz <sameo@...ux.intel.com>,
	socketcan-core@...ts.berlios.de, netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	"David S. Miller" <davem@...emloft.net>
CC:	qi.wang@...el.com, yong.y.wang@...el.com,
	andrew.chih.howe.khor@...el.com, joel.clark@...el.com,
	kok.howg.ewe@...el.com, margie.foster@...el.com
Subject: [PATCH net-next-2.6 v6 04/20] can: EG20T PCH: Add Tx Flow Control

Currently, there is no flow control processing.
Thus, Add flow control processing as
when there is no empty of tx buffer,
netif_stop_queue is called.
When there is empty buffer, netif_wake_queue is called.

Signed-off-by: Tomoya MORINAGA <tomoya-linux@....okisemi.com>
---
 drivers/net/can/pch_can.c |   27 ++++++++-------------------
 1 files changed, 8 insertions(+), 19 deletions(-)

diff --git a/drivers/net/can/pch_can.c b/drivers/net/can/pch_can.c
index 2d4ab0f..8686d93 100644
--- a/drivers/net/can/pch_can.c
+++ b/drivers/net/can/pch_can.c
@@ -899,6 +899,8 @@ MSG_OBJ:
 			dlc = 8;
 		stats->tx_bytes += dlc;
 		stats->tx_packets++;
+		if (int_stat == PCH_TX_OBJ_END)
+			netif_wake_queue(ndev);
 	}
 
 	int_stat = pch_can_int_pending(priv);
@@ -1037,18 +1039,6 @@ static int pch_close(struct net_device *ndev)
 	return 0;
 }
 
-static int pch_get_msg_obj_sts(struct net_device *ndev, u32 obj_id)
-{
-	u32 buffer_status = 0;
-	struct pch_can_priv *priv = netdev_priv(ndev);
-
-	/* Getting the message object status. */
-	buffer_status = (u32) pch_can_get_buffer_status(priv);
-
-	return buffer_status & obj_id;
-}
-
-
 static netdev_tx_t pch_xmit(struct sk_buff *skb, struct net_device *ndev)
 {
 	int i, j;
@@ -1060,17 +1050,16 @@ static netdev_tx_t pch_xmit(struct sk_buff *skb, struct net_device *ndev)
 	if (can_dropped_invalid_skb(ndev, skb))
 		return NETDEV_TX_OK;
 
-	if (priv->tx_obj == PCH_TX_OBJ_END) { /* Point tail Obj */
-		while (pch_get_msg_obj_sts(ndev, (((1 << PCH_TX_OBJ_NUM)-1) <<
-					   PCH_RX_OBJ_NUM)))
-			udelay(500);
+	if (priv->tx_obj == PCH_TX_OBJ_END) {
+		if (ioread32(&priv->regs->treq2) & 0xfc00)
+			netif_stop_queue(ndev);
 
-		priv->tx_obj = PCH_TX_OBJ_START; /* Point head of Tx Obj ID */
-		tx_buffer_avail = priv->tx_obj; /* Point Tail of Tx Obj */
+		tx_buffer_avail = priv->tx_obj;
+		priv->tx_obj = PCH_TX_OBJ_START;
 	} else {
 		tx_buffer_avail = priv->tx_obj;
+		priv->tx_obj++;
 	}
-	priv->tx_obj++;
 
 	/* Attaining the lock. */
 	spin_lock_irqsave(&priv->msgif_reg_lock, flags);
-- 
1.6.0.6
--
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