From: Havard Skinnemoen <hav...@skinnemoen.net>
Remove a couple of unneeded barriers and document the remaining ones.
Signed-off-by: Havard Skinnemoen <hav...@skinnemoen.net>
[nicolas.fe...@atmel.com: split patch in topics]
Signed-off-by: Nicolas Ferre <nicolas.fe...@atmel.com>
---
drivers/net/ethernet/cadence/macb.c | 18 ++++++++++++++----
1 file changed, 14 insertions(+), 4 deletions(-)
diff --git a/drivers/net/ethernet/cadence/macb.c
b/drivers/net/ethernet/cadence/macb.c
index 0931cb7..e7f554d 100644
--- a/drivers/net/ethernet/cadence/macb.c
+++ b/drivers/net/ethernet/cadence/macb.c
@@ -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?)
--
1.8.0
--
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