From c0131dea850b37b2488354ffec6f7072fac9ec2d Mon Sep 17 00:00:00 2001
From: Linas Vepstas <linas@austin.ibm.com>
Date: Tue, 10 Oct 2006 16:11:33 -0500
Subject: [PATCH] --- yaml --- r: 39422 b: refs/heads/master c:
 204e5fa17c7ba45a89989f8da6dfe8e54d64b79b h: refs/heads/master v: v3

---
 [refs]                         |  2 +-
 trunk/drivers/net/spider_net.c | 43 ++++++++++++++++++++++++++++++++++
 trunk/drivers/net/spider_net.h |  8 +++----
 3 files changed, 48 insertions(+), 5 deletions(-)

diff --git a/[refs] b/[refs]
index 1811bc3aaa3e..22298a0b894d 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: b21606a773faffc2b3ec326325c433bdf37ecbdf
+refs/heads/master: 204e5fa17c7ba45a89989f8da6dfe8e54d64b79b
diff --git a/trunk/drivers/net/spider_net.c b/trunk/drivers/net/spider_net.c
index d779a0b9d456..96b5d00c21da 100644
--- a/trunk/drivers/net/spider_net.c
+++ b/trunk/drivers/net/spider_net.c
@@ -684,6 +684,7 @@ spider_net_prepare_tx_descr(struct spider_net_card *card,
 			break;
 		}
 
+	/* Chain the bus address, so that the DMA engine finds this descr. */
 	descr->prev->next_descr_addr = descr->bus_addr;
 
 	card->netdev->trans_start = jiffies; /* set netdev watchdog timer */
@@ -717,6 +718,41 @@ spider_net_release_tx_descr(struct spider_net_card *card)
 	dev_kfree_skb_any(skb);
 }
 
+static void
+spider_net_set_low_watermark(struct spider_net_card *card)
+{
+	int status;
+	int cnt=0;
+	int i;
+	struct spider_net_descr *descr = card->tx_chain.tail;
+
+	/* Measure the length of the queue. */
+	while (descr != card->tx_chain.head) {
+		status = descr->dmac_cmd_status & SPIDER_NET_DESCR_NOT_IN_USE;
+		if (status == SPIDER_NET_DESCR_NOT_IN_USE)
+			break;
+		descr = descr->next;
+		cnt++;
+	}
+
+	/* If TX queue is short, don't even bother with interrupts */
+	if (cnt < card->tx_desc/4)
+		return;
+
+	/* Set low-watermark 3/4th's of the way into the queue. */
+	descr = card->tx_chain.tail;
+	cnt = (cnt*3)/4;
+	for (i=0;i<cnt; i++)
+		descr = descr->next;
+
+	/* Set the new watermark, clear the old watermark */
+	descr->dmac_cmd_status |= SPIDER_NET_DESCR_TXDESFLG;
+	if (card->low_watermark && card->low_watermark != descr)
+		card->low_watermark->dmac_cmd_status =
+		     card->low_watermark->dmac_cmd_status & ~SPIDER_NET_DESCR_TXDESFLG;
+	card->low_watermark = descr;
+}
+
 /**
  * spider_net_release_tx_chain - processes sent tx descriptors
  * @card: adapter structure
@@ -838,6 +874,7 @@ spider_net_xmit(struct sk_buff *skb, struct net_device *netdev)
 		return NETDEV_TX_BUSY;
 	}
 
+	spider_net_set_low_watermark(card);
 	spider_net_kick_tx_dma(card);
 	card->tx_chain.head = card->tx_chain.head->next;
 	spin_unlock_irqrestore(&chain->lock, flags);
@@ -1467,6 +1504,10 @@ spider_net_interrupt(int irq, void *ptr)
 		spider_net_rx_irq_off(card);
 		netif_rx_schedule(netdev);
 	}
+	if (status_reg & SPIDER_NET_TXINT ) {
+		spider_net_cleanup_tx_ring(card);
+		netif_wake_queue(netdev);
+	}
 
 	if (status_reg & SPIDER_NET_ERRINT )
 		spider_net_handle_error_irq(card, status_reg);
@@ -1629,6 +1670,8 @@ spider_net_open(struct net_device *netdev)
 			PCI_DMA_TODEVICE, card->tx_desc))
 		goto alloc_tx_failed;
 
+	card->low_watermark = NULL;
+
 	/* rx_chain is after tx_chain, so offset is descr + tx_count */
 	if (spider_net_init_chain(card, &card->rx_chain,
 			card->descr + card->tx_desc,
diff --git a/trunk/drivers/net/spider_net.h b/trunk/drivers/net/spider_net.h
index 6c9d7ce7f731..1f5c9dc806a0 100644
--- a/trunk/drivers/net/spider_net.h
+++ b/trunk/drivers/net/spider_net.h
@@ -49,7 +49,7 @@ extern char spider_net_driver_name[];
 #define SPIDER_NET_TX_DESCRIPTORS_MIN		16
 #define SPIDER_NET_TX_DESCRIPTORS_MAX		512
 
-#define SPIDER_NET_TX_TIMER			20
+#define SPIDER_NET_TX_TIMER			(HZ/5)
 
 #define SPIDER_NET_RX_CSUM_DEFAULT		1
 
@@ -328,9 +328,7 @@ enum spider_net_int2_status {
 	SPIDER_NET_GRISPDNGINT
 };
 
-#define SPIDER_NET_TXINT	( (1 << SPIDER_NET_GTTEDINT) | \
-				  (1 << SPIDER_NET_GDTDCEINT) | \
-				  (1 << SPIDER_NET_GDTFDCINT) )
+#define SPIDER_NET_TXINT	( (1 << SPIDER_NET_GDTFDCINT) )
 
 /* We rely on flagged descriptor interrupts */
 #define SPIDER_NET_RXINT	( (1 << SPIDER_NET_GDAFDCINT) )
@@ -356,6 +354,7 @@ enum spider_net_int2_status {
 #define SPIDER_NET_DESCR_FORCE_END		0x50000000 /* used in rx and tx */
 #define SPIDER_NET_DESCR_CARDOWNED		0xA0000000 /* used in rx and tx */
 #define SPIDER_NET_DESCR_NOT_IN_USE		0xF0000000
+#define SPIDER_NET_DESCR_TXDESFLG		0x00800000
 
 struct spider_net_descr {
 	/* as defined by the hardware */
@@ -440,6 +439,7 @@ struct spider_net_card {
 
 	struct spider_net_descr_chain tx_chain;
 	struct spider_net_descr_chain rx_chain;
+	struct spider_net_descr *low_watermark;
 
 	struct net_device_stats netdev_stats;