[19/22] Cyclades PC300 driver: improve DCD change detection

[19/22] Cyclades PC300 driver: improve DCD change detection

[Andrea Shepard]

The original version of this driver does not always seem to detect changes to
the DCD bit reliably.  This patch adds checks in more places in the interrupt
handler and in cpc_net_rx()/cpc_queue_xmit(), and seems to fix the problem.

Signed-off-by: Andrea Shepard <andrea@persephoneslair.org>

diff --git a/drivers/net/wan/pc300_drv.c b/drivers/net/wan/pc300_drv.c
index 6cecef5..5e50907 100644
--- a/drivers/net/wan/pc300_drv.c
+++ b/drivers/net/wan/pc300_drv.c
@@ -1960,6 +1960,7 @@ static int cpc_queue_xmit(struct sk_buff *skb, struct net_device *dev)
 	struct net_device_stats *stats = &(dev->stats);
 	int ch = chan->channel;
 	unsigned long flags;
+	uintptr_t scabase = (uintptr_t)(card->hw.scabase);
 #ifdef PC300_DEBUG_TX
 	int i;
 #endif
@@ -1969,6 +1970,36 @@ static int cpc_queue_xmit(struct sk_buff *skb, struct net_device *dev)
 			"%s: cpc_queue_xmit called wih %d bytes\n",
 			dev->name, skb->len);
 #endif
+	if (cpc_readb(scabase + M_REG(ST3, ch)) & ST3_DCD) {
+		if (netif_carrier_ok(dev)) {
+			printk(KERN_INFO
+					"%s: DCD is OFF. Going administrative down.\n",
+					dev->name);
+#ifdef CONFIG_PC300_MLPPP
+			if (chan->conf.proto != PC300_PROTO_MLPPP)
+				netif_carrier_off(dev);
+#else
+			netif_carrier_off(dev);
+#endif
+			card->chan[ch].d.line_off++;
+		}
+	} else {        /* DCD = 1 */
+		if (!netif_carrier_ok(dev)) {
+			printk(KERN_INFO
+					"%s: DCD is ON. Going administrative up.\n",
+					dev->name);
+#ifdef CONFIG_PC300_MLPPP
+			if (chan->conf.proto != PC300_PROTO_MLPPP) {
+				/* verify if driver is not TTY */
+				netif_carrier_on(dev);
+			}
+#else
+			netif_carrier_on(dev);
+#endif
+			card->chan[ch].d.line_on++;
+		}
+	}
+
 	if (chan->conf.monitor) {
 		/* In monitor mode no Tx is done: ignore packet */
 		dev_kfree_skb(skb);
@@ -2106,12 +2137,21 @@ static void cpc_net_rx(struct net_device *dev)
 #endif
 	int rxb;
 	struct sk_buff *skb;
+	uintptr_t scabase = (uintptr_t)(card->hw.scabase);
 
 	while (1) {
 		if ((rxb = dma_get_rx_frame_size(card, ch)) == -1)
 			return;
 
 		if (!netif_carrier_ok(dev)) {
+			if (!(cpc_readb(scabase + M_REG(ST3, ch)) & ST3_DCD)) {
+				printk(KERN_INFO
+						"%s: DCD ON - going up\n",
+						dev->name);
+				netif_carrier_on(dev);
+			}
+		}
+		if (!netif_carrier_ok(dev)) {
 			/* DCD must be OFF: drop packet */
 			printk(KERN_INFO
 				"%s : DCD is OFF - drop %d rx bytes\n",
@@ -3625,8 +3665,12 @@ static void cpc_closech(pc300dev_t *d)
 int cpc_open(struct net_device *dev)
 {
 	pc300dev_t *d = (pc300dev_t *) dev_to_hdlc(dev)->priv;
+	pc300ch_t *chan = (pc300ch_t *) d->chan;
+	int ch = chan->channel;
+	pc300_t *card = (pc300_t *) chan->card;
 	struct ifreq ifr;
 	int result;
+	uintptr_t scabase = (uintptr_t)(card->hw.scabase);
 
 #ifdef	PC300_DEBUG_OTHER
 	printk(KERN_DEBUG "pc300: cpc_open\n");
@@ -3645,6 +3689,11 @@ int cpc_open(struct net_device *dev)
 	printk(KERN_DEBUG "%s: starting queue for open\n", dev->name);
 #endif
 	netif_start_queue(dev);
+	if (cpc_readb(scabase + M_REG(ST3, ch)) & ST3_DCD)
+		netif_carrier_off(dev);
+	else
+		netif_carrier_on(dev);
+
 	return 0;
 
 err_out: