net: axienet: increase reset timeout

The previous timeout of 1ms was too short to handle some cases where the
core is reset just after the input clocks were started, which will
be introduced in an upcoming patch. Increase the timeout to 50ms. Also
simplify the reset timeout checking to use read_poll_timeout.

Fixes: 8a3b7a25 ("drivers/net/ethernet/xilinx: added Xilinx AXI Ethernet driver")
Signed-off-by: Robert Hancock <robert.hancock@calian.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/xilinx/xilinx_axienet_main.c

@@ -496,7 +496,8 @@ static void axienet_setoptions(struct net_device *ndev, u32 options)
 
 static int __axienet_device_reset(struct axienet_local *lp)
 {
-	u32 timeout;
+	u32 value;
+	int ret;
 
 	/* Reset Axi DMA. This would reset Axi Ethernet core as well. The reset
 	 * process of Axi DMA takes a while to complete as all pending
@@ -506,15 +507,13 @@ static int __axienet_device_reset(struct axienet_local *lp)
 	 * they both reset the entire DMA core, so only one needs to be used.
 	 */
 	axienet_dma_out32(lp, XAXIDMA_TX_CR_OFFSET, XAXIDMA_CR_RESET_MASK);
-	timeout = DELAY_OF_ONE_MILLISEC;
-	while (axienet_dma_in32(lp, XAXIDMA_TX_CR_OFFSET) &
-				XAXIDMA_CR_RESET_MASK) {
-		udelay(1);
-		if (--timeout == 0) {
-			netdev_err(lp->ndev, "%s: DMA reset timeout!\n",
-				   __func__);
-			return -ETIMEDOUT;
-		}
+	ret = read_poll_timeout(axienet_dma_in32, value,
+				!(value & XAXIDMA_CR_RESET_MASK),
+				DELAY_OF_ONE_MILLISEC, 50000, false, lp,
+				XAXIDMA_TX_CR_OFFSET);
+	if (ret) {
+		dev_err(lp->dev, "%s: DMA reset timeout!\n", __func__);
+		return ret;
 	}
 
 	return 0;