[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 <ebs@ebshome.net>
Signed-off-by: Jeff Garzik <jgarzik@pobox.com>

2 files changed, 31 insertions, 9 deletions

diff --git a/drivers/net/ibm_emac/ibm_emac_core.c b/drivers/net/ibm_emac/ibm_emac_core.c
index eb7d6947871..1da8a66f91e 100644
--- a/drivers/net/ibm_emac/ibm_emac_core.c
+++ b/drivers/net/ibm_emac/ibm_emac_core.c
@@ -65,7 +65,7 @@
  */
 
 #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);
@@ -158,6 +158,14 @@ static inline void emac_report_timeout_error(struct ocp_enet_private *dev,
 #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",
@@ -222,10 +230,12 @@ static void emac_tx_disable(struct ocp_enet_private *dev)
 
         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");
         }
@@ -248,9 +258,11 @@ static void emac_rx_enable(struct ocp_enet_private *dev)
         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");
@@ -273,10 +285,12 @@ static void emac_rx_disable(struct ocp_enet_private *dev)
 
         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");
         }
@@ -395,6 +409,7 @@ static int emac_configure(struct ocp_enet_private *dev)
         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)) {
@@ -409,12 +424,16 @@ static int emac_configure(struct ocp_enet_private *dev)
                         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;
@@ -2048,6 +2067,7 @@ static int __init emac_probe(struct ocp_device *ocpdev)
         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;
diff --git a/drivers/net/ibm_emac/ibm_emac_core.h b/drivers/net/ibm_emac/ibm_emac_core.h
index e9b44d030ac..911abbaf471 100644
--- a/drivers/net/ibm_emac/ibm_emac_core.h
+++ b/drivers/net/ibm_emac/ibm_emac_core.h
@@ -189,6 +189,8 @@ struct ocp_enet_private {
         struct timer_list               link_timer;
         int                             reset_failed;
 
+        int                             stop_timeout;   /* in us */
+
         struct ibm_emac_error_stats     estats;
         struct net_device_stats         nstats;