net: ftgmac100: access hardware register after clock ready

AST2600 MAC register 0x58 is writable only when the MAC clock is
enabled.  Usually, the MAC clock is enabled by the bootloader so
register 0x58 is set normally when the bootloader is involved.  To make
ast2600 ftgmac100 work without the bootloader, postpone the register
write until the clock is ready.

Fixes: 137d23c ("net: ftgmac100: Fix Aspeed ast2600 TX hang issue")
Signed-off-by: Dylan Hung <dylan_hung@aspeedtech.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Author: aspeeddylan

drivers/net/ethernet/faraday/ftgmac100.c

@@ -1835,11 +1835,6 @@ static int ftgmac100_probe(struct platform_device *pdev)
 		priv->rxdes0_edorr_mask = BIT(30);
 		priv->txdes0_edotr_mask = BIT(30);
 		priv->is_aspeed = true;
-		/* Disable ast2600 problematic HW arbitration */
-		if (of_device_is_compatible(np, "aspeed,ast2600-mac")) {
-			iowrite32(FTGMAC100_TM_DEFAULT,
-				  priv->base + FTGMAC100_OFFSET_TM);
-		}
 	} else {
 		priv->rxdes0_edorr_mask = BIT(15);
 		priv->txdes0_edotr_mask = BIT(15);
@@ -1911,6 +1906,11 @@ static int ftgmac100_probe(struct platform_device *pdev)
 		err = ftgmac100_setup_clk(priv);
 		if (err)
 			goto err_phy_connect;
+
+		/* Disable ast2600 problematic HW arbitration */
+		if (of_device_is_compatible(np, "aspeed,ast2600-mac"))
+			iowrite32(FTGMAC100_TM_DEFAULT,
+				  priv->base + FTGMAC100_OFFSET_TM);
 	}
 
 	/* Default ring sizes */