[PATCH] ibm_emac: fix graceful stop timeout handling

This patch fixes graceful stop timeout handling in PPC4xx EMAC driver.

Currently, when we stop TX/RX channels we just do some number of loops
without relying on actual spent time. This has finally bitten me on
one of our systems (heavy network traffic during start up, RX channel
is stopped several times to configure multicast list).

Graceful channel stop can take up to 1 frame time, so I've added
device specific timeout counter which depends on current link speed
and calls to udelay() to really wait required amount of time before
giving up.

Signed-off-by: Eugene Surovegin <[e-mail]>
Signed-off-by: Jeff Garzik <[e-mail]>

drivers/net/ibm_emac/ibm_emac_core.c

···
  */
 
 #define DRV_NAME        "emac"
-#define DRV_VERSION     "3.53"
+#define DRV_VERSION     "3.54"
 #define DRV_DESC        "PPC 4xx OCP EMAC driver"
 
 MODULE_DESCRIPTION(DRV_DESC);
···
 #define PHY_POLL_LINK_ON	HZ
 #define PHY_POLL_LINK_OFF	(HZ / 5)
 
+/* Graceful stop timeouts in us. 
+ * We should allow up to 1 frame time (full-duplex, ignoring collisions) 
+ */
+#define STOP_TIMEOUT_10		1230	
+#define STOP_TIMEOUT_100	124
+#define STOP_TIMEOUT_1000	13
+#define STOP_TIMEOUT_1000_JUMBO	73
+
 /* Please, keep in sync with struct ibm_emac_stats/ibm_emac_error_stats */
 static const char emac_stats_keys[EMAC_ETHTOOL_STATS_COUNT][ETH_GSTRING_LEN] = {
 	"rx_packets", "rx_bytes", "tx_packets", "tx_bytes", "rx_packets_csum",
···
 
 	r = in_be32(&p->mr0);
 	if (r & EMAC_MR0_TXE) {
-		int n = 300;
+		int n = dev->stop_timeout;
 		out_be32(&p->mr0, r & ~EMAC_MR0_TXE);
-		while (!(in_be32(&p->mr0) & EMAC_MR0_TXI) && n)
+		while (!(in_be32(&p->mr0) & EMAC_MR0_TXI) && n) {
+			udelay(1);
 			--n;
+		}	
 		if (unlikely(!n))
 			emac_report_timeout_error(dev, "TX disable timeout");
 	}
···
 	if (!(r & EMAC_MR0_RXE)) {
 		if (unlikely(!(r & EMAC_MR0_RXI))) {
 			/* Wait if previous async disable is still in progress */
-			int n = 100;
-			while (!(r = in_be32(&p->mr0) & EMAC_MR0_RXI) && n)
+			int n = dev->stop_timeout;
+			while (!(r = in_be32(&p->mr0) & EMAC_MR0_RXI) && n) {
+				udelay(1);
 				--n;
+			}	
 			if (unlikely(!n))
 				emac_report_timeout_error(dev,
 							  "RX disable timeout");
···
 
 	r = in_be32(&p->mr0);
 	if (r & EMAC_MR0_RXE) {
-		int n = 300;
+		int n = dev->stop_timeout;
 		out_be32(&p->mr0, r & ~EMAC_MR0_RXE);
-		while (!(in_be32(&p->mr0) & EMAC_MR0_RXI) && n)
+		while (!(in_be32(&p->mr0) & EMAC_MR0_RXI) && n) {
+			udelay(1);
 			--n;
+		}	
 		if (unlikely(!n))
 			emac_report_timeout_error(dev, "RX disable timeout");
 	}
···
 	r = EMAC_MR1_BASE(emac_opb_mhz()) | EMAC_MR1_VLE | EMAC_MR1_IST;
 	if (dev->phy.duplex == DUPLEX_FULL)
 		r |= EMAC_MR1_FDE;
+	dev->stop_timeout = STOP_TIMEOUT_10;
 	switch (dev->phy.speed) {
 	case SPEED_1000:
 		if (emac_phy_gpcs(dev->phy.mode)) {
···
 			r |= EMAC_MR1_MF_1000;
 		r |= EMAC_MR1_RFS_16K;
 		gige = 1;
-		
-		if (dev->ndev->mtu > ETH_DATA_LEN)
+
+		if (dev->ndev->mtu > ETH_DATA_LEN) {
 			r |= EMAC_MR1_JPSM;
+			dev->stop_timeout = STOP_TIMEOUT_1000_JUMBO;
+		} else
+			dev->stop_timeout = STOP_TIMEOUT_1000;
 		break;
 	case SPEED_100:
 		r |= EMAC_MR1_MF_100;
+		dev->stop_timeout = STOP_TIMEOUT_100;
 		/* Fall through */
 	default:
 		r |= EMAC_MR1_RFS_4K;
···
 	dev->phy.duplex = DUPLEX_FULL;
 	dev->phy.autoneg = AUTONEG_DISABLE;
 	dev->phy.pause = dev->phy.asym_pause = 0;
+	dev->stop_timeout = STOP_TIMEOUT_100;
 	init_timer(&dev->link_timer);
 	dev->link_timer.function = emac_link_timer;
 	dev->link_timer.data = (unsigned long)dev;

drivers/net/ibm_emac/ibm_emac_core.h

···
 	struct timer_list		link_timer;
 	int				reset_failed;
 
+	int				stop_timeout;	/* in us */
+
 	struct ibm_emac_error_stats	estats;
 	struct net_device_stats		nstats;