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net/macb: memory barriers cleanup 

Remove a couple of unneeded barriers and document the remaining ones.

Signed-off-by: Havard Skinnemoen <havard@skinnemoen.net>
[nicolas.ferre@atmel.com: split patch in topics]
Signed-off-by: Nicolas Ferre <nicolas.ferre@atmel.com>
Tested-by: Joachim Eastwood <manabian@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Havard Skinnemoen 2012-10-31 06:04:51 +00:00 committed by David S. Miller
parent 140b7552fd
commit 03dbe05fe4
1 changed files with 14 additions and 4 deletions
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18
drivers/net/ethernet/cadence/macb.c
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@ -373,7 +373,9 @@ static void macb_tx(struct macb *bp)
BUG_ON(skb == NULL);
/* Make hw descriptor updates visible to CPU */
rmb();
bufstat = bp->tx_ring[tail].ctrl;
if (!(bufstat & MACB_BIT(TX_USED)))
@ -416,7 +418,10 @@ static int macb_rx_frame(struct macb *bp, unsigned int first_frag,
if (frag == last_frag)
break;
}
/* Make descriptor updates visible to hardware */
wmb();
return 1;
}
@ -437,12 +442,14 @@ static int macb_rx_frame(struct macb *bp, unsigned int first_frag,
frag_len);
offset += RX_BUFFER_SIZE;
bp->rx_ring[frag].addr &= ~MACB_BIT(RX_USED);
wmb();
if (frag == last_frag)
break;
}
/* Make descriptor updates visible to hardware */
wmb();
skb->protocol = eth_type_trans(skb, bp->dev);
bp->stats.rx_packets++;
@ -462,6 +469,8 @@ static void discard_partial_frame(struct macb *bp, unsigned int begin,
for (frag = begin; frag != end; frag = NEXT_RX(frag))
bp->rx_ring[frag].addr &= ~MACB_BIT(RX_USED);
/* Make descriptor updates visible to hardware */
wmb();
/*
@ -480,7 +489,9 @@ static int macb_rx(struct macb *bp, int budget)
for (; budget > 0; tail = NEXT_RX(tail)) {
u32 addr, ctrl;
/* Make hw descriptor updates visible to CPU */
rmb();
addr = bp->rx_ring[tail].addr;
ctrl = bp->rx_ring[tail].ctrl;
@ -675,6 +686,8 @@ static int macb_start_xmit(struct sk_buff *skb, struct net_device *dev)
bp->tx_ring[entry].addr = mapping;
bp->tx_ring[entry].ctrl = ctrl;
/* Make newly initialized descriptor visible to hardware */
wmb();
entry = NEXT_TX(entry);
@ -783,9 +796,6 @@ static void macb_init_rings(struct macb *bp)
static void macb_reset_hw(struct macb *bp)
{
/* Make sure we have the write buffer for ourselves */
wmb();
/*
* Disable RX and TX (XXX: Should we halt the transmission
* more gracefully?)