ibm_newemac: Workaround reset timeout when no link

With some PHYs, when the link goes away, the EMAC reset fails due
to the loss of the RX clock I believe.

The old EMAC driver worked around that using some internal chip-specific
clock force bits that are different on various 44x implementations.

This is an attempt at doing it differently, by avoiding the reset when
there is no link, but forcing loopback mode instead. It seems to work
on my Taishan 440GX based board so far.
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Acked-by: Stefan Roese <sr@denx.de>
Signed-off-by: Jeff Garzik <jeff@garzik.org>

drivers/net/ibm_newemac/core.c

@@ -464,26 +464,34 @@ static int emac_configure(struct emac_instance *dev)
 {
 	struct emac_regs __iomem *p = dev->emacp;
 	struct net_device *ndev = dev->ndev;
-	int tx_size, rx_size;
+	int tx_size, rx_size, link = netif_carrier_ok(dev->ndev);
 	u32 r, mr1 = 0;
 
 	DBG(dev, "configure" NL);
 
-	if (emac_reset(dev) < 0)
+	if (!link) {
+		out_be32(&p->mr1, in_be32(&p->mr1)
+			 | EMAC_MR1_FDE | EMAC_MR1_ILE);
+		udelay(100);
+	} else if (emac_reset(dev) < 0)
 		return -ETIMEDOUT;
 
 	if (emac_has_feature(dev, EMAC_FTR_HAS_TAH))
 		tah_reset(dev->tah_dev);
 
-	DBG(dev, " duplex = %d, pause = %d, asym_pause = %d\n",
-	    dev->phy.duplex, dev->phy.pause, dev->phy.asym_pause);
+	DBG(dev, " link = %d duplex = %d, pause = %d, asym_pause = %d\n",
+	    link, dev->phy.duplex, dev->phy.pause, dev->phy.asym_pause);
 
 	/* Default fifo sizes */
 	tx_size = dev->tx_fifo_size;
 	rx_size = dev->rx_fifo_size;
 
+	/* No link, force loopback */
+	if (!link)
+		mr1 = EMAC_MR1_FDE | EMAC_MR1_ILE;
+
 	/* Check for full duplex */
-	if (dev->phy.duplex == DUPLEX_FULL)
+	else if (dev->phy.duplex == DUPLEX_FULL)
 		mr1 |= EMAC_MR1_FDE | EMAC_MR1_MWSW_001;
 
 	/* Adjust fifo sizes, mr1 and timeouts based on link speed */
@@ -1165,9 +1173,9 @@ static void emac_link_timer(struct work_struct *work)
 		link_poll_interval = PHY_POLL_LINK_ON;
 	} else {
 		if (netif_carrier_ok(dev->ndev)) {
-			emac_reinitialize(dev);
 			netif_carrier_off(dev->ndev);
 			netif_tx_disable(dev->ndev);
+			emac_reinitialize(dev);
 			emac_print_link_status(dev);
 		}
 		link_poll_interval = PHY_POLL_LINK_OFF;