cxgb4: halt chip before flashing PHY firmware image

When using firmware-assisted PHY firmware image write to flash,
halt the chip before beginning the flash write operation to allow
the running firmware to store the image persistently. Otherwise,
the running firmware will only store the PHY image in local on-chip
RAM, which will be lost after next reset.

Fixes: 4ee339e1 ("cxgb4: add support to flash PHY image")
Signed-off-by: Rahul Lakkireddy <rahul.lakkireddy@chelsio.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/chelsio/cxgb4/cxgb4_ethtool.c

@@ -1337,11 +1337,27 @@ static int cxgb4_ethtool_flash_phy(struct net_device *netdev,
 		return ret;
 	}
 
+	/* We have to RESET the chip/firmware because we need the
+	 * chip in uninitialized state for loading new PHY image.
+	 * Otherwise, the running firmware will only store the PHY
+	 * image in local RAM which will be lost after next reset.
+	 */
+	ret = t4_fw_reset(adap, adap->mbox, PIORSTMODE_F | PIORST_F);
+	if (ret < 0) {
+		dev_err(adap->pdev_dev,
+			"Set FW to RESET for flashing PHY FW failed. ret: %d\n",
+			ret);
+		return ret;
+	}
+
 	ret = t4_load_phy_fw(adap, MEMWIN_NIC, NULL, data, size);
-	if (ret)
-		dev_err(adap->pdev_dev, "Failed to load PHY FW\n");
+	if (ret < 0) {
+		dev_err(adap->pdev_dev, "Failed to load PHY FW. ret: %d\n",
+			ret);
+		return ret;
+	}
 
-	return ret;
+	return 0;
 }
 
 static int cxgb4_ethtool_flash_fw(struct net_device *netdev,