From: Madalin Bucur <madalin.bucur@nxp.com>
Date: Thu, 31 Oct 2019 16:37:49 +0200
Subject: dpaa_eth: perform DMA unmapping before read
References: bsc#1175407

Git-commit: c70fd3182caef014e6c628b412f81aa57a3ef9e4
Patch-mainline: v5.5-rc1

DMA unmapping is required before accessing the HW provided timestamping
information.

Fixes: 4664856e9ca2 ("dpaa_eth: add support for hardware timestamping")
Signed-off-by: Madalin Bucur <madalin.bucur@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Mian Yousaf Kaukab <ykaukab@suse.de>
---
 drivers/net/ethernet/freescale/dpaa/dpaa_eth.c |   31 +++++++++++++------------
 1 file changed, 17 insertions(+), 14 deletions(-)

--- a/drivers/net/ethernet/freescale/dpaa/dpaa_eth.c
+++ b/drivers/net/ethernet/freescale/dpaa/dpaa_eth.c
@@ -1591,18 +1591,6 @@ static struct sk_buff *dpaa_cleanup_tx_f
 	skbh = (struct sk_buff **)phys_to_virt(addr);
 	skb = *skbh;
 
-	if (priv->tx_tstamp && skb_shinfo(skb)->tx_flags & SKBTX_HW_TSTAMP) {
-		memset(&shhwtstamps, 0, sizeof(shhwtstamps));
-
-		if (!fman_port_get_tstamp(priv->mac_dev->port[TX], (void *)skbh,
-					  &ns)) {
-			shhwtstamps.hwtstamp = ns_to_ktime(ns);
-			skb_tstamp_tx(skb, &shhwtstamps);
-		} else {
-			dev_warn(dev, "fman_port_get_tstamp failed!\n");
-		}
-	}
-
 	if (unlikely(qm_fd_get_format(fd) == qm_fd_sg)) {
 		nr_frags = skb_shinfo(skb)->nr_frags;
 		dma_unmap_single(priv->tx_dma_dev, addr,
@@ -1626,13 +1614,28 @@ static struct sk_buff *dpaa_cleanup_tx_f
 				       qm_sg_entry_get_len(&sgt[i]), dma_dir);
 		}
 
-		/* Free the page frag that we allocated on Tx */
-		skb_free_frag(phys_to_virt(addr));
 	} else {
 		dma_unmap_single(priv->tx_dma_dev, addr,
 				 skb_tail_pointer(skb) - (u8 *)skbh, dma_dir);
 	}
 
+	/* DMA unmapping is required before accessing the HW provided info */
+	if (priv->tx_tstamp && skb_shinfo(skb)->tx_flags & SKBTX_HW_TSTAMP) {
+		memset(&shhwtstamps, 0, sizeof(shhwtstamps));
+
+		if (!fman_port_get_tstamp(priv->mac_dev->port[TX], (void *)skbh,
+					  &ns)) {
+			shhwtstamps.hwtstamp = ns_to_ktime(ns);
+			skb_tstamp_tx(skb, &shhwtstamps);
+		} else {
+			dev_warn(dev, "fman_port_get_tstamp failed!\n");
+		}
+	}
+
+	if (qm_fd_get_format(fd) == qm_fd_sg)
+		/* Free the page frag that we allocated on Tx */
+		skb_free_frag(phys_to_virt(addr));
+
 	return skb;
 }