Change MDIO read/write to poll for completion rather than waiting
an arbitrary length of time.  Note this changes the semantics of the
MDIO_DELAY definition - it is now a maximal loop count, rather than
a time delay in microseconds.

--- linux-2.6.8-rc3/drivers/net/ibm_emac/ibm_emac_core.c	2004-08-05 14:54:56.000000000 -0400
+++ linux-2.6-devel/drivers/net/ibm_emac/ibm_emac_core.c	2004-08-05 15:08:50.000000000 -0400
@@ -367,6 +371,7 @@

 int emac_phy_read(struct net_device *dev, int mii_id, int reg)
 {
+	int count;
 	uint32_t stacr;
 	struct ocp_enet_private *fep = dev->priv;
 	emac_t *emacp = fep->emacp;
@@ -398,8 +403,11 @@

 	out_be32(&emacp->em0stacr, stacr);

-	udelay(MDIO_DELAY);
-	stacr = in_be32(&emacp->em0stacr);
+	count =  0;
+	while ((((stacr = in_be32(&emacp->em0stacr)) & EMAC_STACR_OC) == 0)
+					&& (count++ < MDIO_DELAY))
+		udelay(1);
+	MDIO_DEBUG((" (count was %d)\n", count));

 	if ((stacr & EMAC_STACR_OC) == 0) {
 		printk(KERN_WARNING "%s: PHY read timeout #2!\n", dev->name);
@@ -419,6 +427,7 @@

 void emac_phy_write(struct net_device *dev, int mii_id, int reg, int data)
 {
+	int count;
 	uint32_t stacr;
 	struct ocp_enet_private *fep = dev->priv;
 	emac_t *emacp = fep->emacp;
@@ -451,9 +460,13 @@

 	out_be32(&emacp->em0stacr, stacr);

-	udelay(MDIO_DELAY);
+	count = 0;
+	while (((stacr = in_be32(&emacp->em0stacr) & EMAC_STACR_OC) == 0)
+					&& (count++ < 5000))
+		udelay(1);
+	MDIO_DEBUG((" (count was %d)\n", count));

-	if (((stacr = in_be32(&emacp->em0stacr)) & EMAC_STACR_OC) == 0)
+	if ((stacr & EMAC_STACR_OC) == 0)
 		printk(KERN_WARNING "%s: PHY write timeout #2!\n", dev->name);

 	/* Check for a write error */