stmmac: add length field to dma data

Currently, the code pulls out the length field when
unmapping a buffer directly from the descriptor. This will result
in an uncached read to a dma_alloc_coherent() region. There is no
need to do this, so this patch simply puts the value directly into
a data structure which will hit the cache.

Signed-off-by: Fabrice Gasnier <fabrice.gasnier@st.com>
Signed-off-by: Giuseppe Cavallaro <peppe.cavallaro@st.com>
Signed-off-by: Alexandre TORGUE <alexandre.torgue@st.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/stmicro/stmmac/chain_mode.c

@@ -49,6 +49,7 @@ static int stmmac_jumbo_frm(void *p, struct sk_buff *skb, int csum)
 	if (dma_mapping_error(priv->device, desc->des2))
 		return -1;
 	priv->tx_skbuff_dma[entry].buf = desc->des2;
+	priv->tx_skbuff_dma[entry].len = bmax;
 	priv->hw->desc->prepare_tx_desc(desc, 1, bmax, csum, STMMAC_CHAIN_MODE);
 
 	while (len != 0) {
@@ -63,6 +64,7 @@ static int stmmac_jumbo_frm(void *p, struct sk_buff *skb, int csum)
 			if (dma_mapping_error(priv->device, desc->des2))
 				return -1;
 			priv->tx_skbuff_dma[entry].buf = desc->des2;
+			priv->tx_skbuff_dma[entry].len = bmax;
 			priv->hw->desc->prepare_tx_desc(desc, 0, bmax, csum,
 							STMMAC_CHAIN_MODE);
 			priv->hw->desc->set_tx_owner(desc);
@@ -75,6 +77,7 @@ static int stmmac_jumbo_frm(void *p, struct sk_buff *skb, int csum)
 			if (dma_mapping_error(priv->device, desc->des2))
 				return -1;
 			priv->tx_skbuff_dma[entry].buf = desc->des2;
+			priv->tx_skbuff_dma[entry].len = len;
 			priv->hw->desc->prepare_tx_desc(desc, 0, len, csum,
 							STMMAC_CHAIN_MODE);
 			priv->hw->desc->set_tx_owner(desc);

drivers/net/ethernet/stmicro/stmmac/ring_mode.c

@@ -56,6 +56,8 @@ static int stmmac_jumbo_frm(void *p, struct sk_buff *skb, int csum)
 			return -1;
 
 		priv->tx_skbuff_dma[entry].buf = desc->des2;
+		priv->tx_skbuff_dma[entry].len = bmax;
+
 		desc->des3 = desc->des2 + BUF_SIZE_4KiB;
 		priv->hw->desc->prepare_tx_desc(desc, 1, bmax, csum,
 						STMMAC_RING_MODE);
@@ -73,6 +75,8 @@ static int stmmac_jumbo_frm(void *p, struct sk_buff *skb, int csum)
 		if (dma_mapping_error(priv->device, desc->des2))
 			return -1;
 		priv->tx_skbuff_dma[entry].buf = desc->des2;
+		priv->tx_skbuff_dma[entry].len = len;
+
 		desc->des3 = desc->des2 + BUF_SIZE_4KiB;
 		priv->hw->desc->prepare_tx_desc(desc, 0, len, csum,
 						STMMAC_RING_MODE);
@@ -84,6 +88,7 @@ static int stmmac_jumbo_frm(void *p, struct sk_buff *skb, int csum)
 		if (dma_mapping_error(priv->device, desc->des2))
 			return -1;
 		priv->tx_skbuff_dma[entry].buf = desc->des2;
+		priv->tx_skbuff_dma[entry].len = nopaged_len;
 		desc->des3 = desc->des2 + BUF_SIZE_4KiB;
 		priv->hw->desc->prepare_tx_desc(desc, 1, nopaged_len, csum,
 						STMMAC_RING_MODE);

drivers/net/ethernet/stmicro/stmmac/stmmac.h

@@ -45,6 +45,7 @@ struct stmmac_resources {
 struct stmmac_tx_info {
 	dma_addr_t buf;
 	bool map_as_page;
+	unsigned len;
 };
 
 struct stmmac_priv {

drivers/net/ethernet/stmicro/stmmac/stmmac_main.c

@@ -1093,6 +1093,7 @@ static int init_dma_desc_rings(struct net_device *dev, gfp_t flags)
 		p->des2 = 0;
 		priv->tx_skbuff_dma[i].buf = 0;
 		priv->tx_skbuff_dma[i].map_as_page = false;
+		priv->tx_skbuff_dma[i].len = 0;
 		priv->tx_skbuff[i] = NULL;
 	}
 
@@ -1136,12 +1137,12 @@ static void dma_free_tx_skbufs(struct stmmac_priv *priv)
 			if (priv->tx_skbuff_dma[i].map_as_page)
 				dma_unmap_page(priv->device,
 					       priv->tx_skbuff_dma[i].buf,
-					       priv->hw->desc->get_tx_len(p),
+					       priv->tx_skbuff_dma[i].len,
 					       DMA_TO_DEVICE);
 			else
 				dma_unmap_single(priv->device,
 						 priv->tx_skbuff_dma[i].buf,
-						 priv->hw->desc->get_tx_len(p),
+						 priv->tx_skbuff_dma[i].len,
 						 DMA_TO_DEVICE);
 		}
 
@@ -1347,12 +1348,12 @@ static void stmmac_tx_clean(struct stmmac_priv *priv)
 			if (priv->tx_skbuff_dma[entry].map_as_page)
 				dma_unmap_page(priv->device,
 					       priv->tx_skbuff_dma[entry].buf,
-					       priv->hw->desc->get_tx_len(p),
+					       priv->tx_skbuff_dma[entry].len,
 					       DMA_TO_DEVICE);
 			else
 				dma_unmap_single(priv->device,
 						 priv->tx_skbuff_dma[entry].buf,
-						 priv->hw->desc->get_tx_len(p),
+						 priv->tx_skbuff_dma[entry].len,
 						 DMA_TO_DEVICE);
 			priv->tx_skbuff_dma[entry].buf = 0;
 			priv->tx_skbuff_dma[entry].map_as_page = false;
@@ -1986,6 +1987,7 @@ static netdev_tx_t stmmac_xmit(struct sk_buff *skb, struct net_device *dev)
 		if (dma_mapping_error(priv->device, desc->des2))
 			goto dma_map_err;
 		priv->tx_skbuff_dma[entry].buf = desc->des2;
+		priv->tx_skbuff_dma[entry].len = nopaged_len;
 		priv->hw->desc->prepare_tx_desc(desc, 1, nopaged_len,
 						csum_insertion, priv->mode);
 	} else {
@@ -2014,6 +2016,7 @@ static netdev_tx_t stmmac_xmit(struct sk_buff *skb, struct net_device *dev)
 
 		priv->tx_skbuff_dma[entry].buf = desc->des2;
 		priv->tx_skbuff_dma[entry].map_as_page = true;
+		priv->tx_skbuff_dma[entry].len = len;
 		priv->hw->desc->prepare_tx_desc(desc, 0, len, csum_insertion,
 						priv->mode);
 		wmb();