From: Shiraz Hashim <shiraz.hashim@st.com>
Date: Sun, 17 Jul 2011 20:54:08 +0000 (+0000)
Subject: stmmac: add memory barriers at appropriate places
X-Git-Tag: accepted/tizen/common/20141203.182822~6771^2~105
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=eb0dc4bb2e22c04964d6e9545e86f629f117108b;p=platform%2Fkernel%2Flinux-arm64.git

stmmac: add memory barriers at appropriate places

This patch, provided by ST SPEAr developers,
has fixed a problem raised on ARM CA9 where
happened that the dma_transmission was enabled before
the dma descriptors were properly filled. To guarantee this
data memory barriers have been explicity used in the driver.

Signed-off-by: Shiraz Hashim <shiraz.hashim@st.com>
Signed-off-by: Giuseppe Cavallaro <peppe.cavallaro@st.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
---

diff --git a/drivers/net/stmmac/stmmac_main.c b/drivers/net/stmmac/stmmac_main.c
index d4adc80..c8c9e5b 100644
--- a/drivers/net/stmmac/stmmac_main.c
+++ b/drivers/net/stmmac/stmmac_main.c
@@ -1045,6 +1045,7 @@ static netdev_tx_t stmmac_xmit(struct sk_buff *skb, struct net_device *dev)
 					  len, DMA_TO_DEVICE);
 		priv->tx_skbuff[entry] = NULL;
 		priv->hw->desc->prepare_tx_desc(desc, 0, len, csum_insertion);
+		wmb();
 		priv->hw->desc->set_tx_owner(desc);
 	}
 
@@ -1056,6 +1057,9 @@ static netdev_tx_t stmmac_xmit(struct sk_buff *skb, struct net_device *dev)
 	if (likely(priv->tm->enable))
 		priv->hw->desc->clear_tx_ic(desc);
 #endif
+
+	wmb();
+
 	/* To avoid raise condition */
 	priv->hw->desc->set_tx_owner(first);
 
@@ -1118,6 +1122,7 @@ static inline void stmmac_rx_refill(struct stmmac_priv *priv)
 			}
 			RX_DBG(KERN_INFO "\trefill entry #%d\n", entry);
 		}
+		wmb();
 		priv->hw->desc->set_rx_owner(p + entry);
 	}
 }