stmmac: review RX/TX ring management
This patch is to rework the ring management now optimized.
The indexes into the ring buffer are always incremented, and
the entry is accessed via doing a modulo to find the "real"
position in the ring.
It is inefficient, modulo is an expensive operation.
The formula [(entry + 1) & (size - 1)] is now adopted on
a ring that is power-of-2 in size.
Then, the number of elements cannot be set by command line but
it is fixed.
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>
diff --git a/drivers/net/ethernet/stmicro/stmmac/chain_mode.c b/drivers/net/ethernet/stmicro/stmmac/chain_mode.c
index cf28dab..2763772 100644
--- a/drivers/net/ethernet/stmicro/stmmac/chain_mode.c
+++ b/drivers/net/ethernet/stmicro/stmmac/chain_mode.c
@@ -31,8 +31,7 @@
static int stmmac_jumbo_frm(void *p, struct sk_buff *skb, int csum)
{
struct stmmac_priv *priv = (struct stmmac_priv *)p;
- unsigned int txsize = priv->dma_tx_size;
- unsigned int entry = priv->cur_tx % txsize;
+ unsigned int entry = priv->cur_tx;
struct dma_desc *desc = priv->dma_tx + entry;
unsigned int nopaged_len = skb_headlen(skb);
unsigned int bmax;
@@ -54,7 +53,7 @@
while (len != 0) {
priv->tx_skbuff[entry] = NULL;
- entry = (++priv->cur_tx) % txsize;
+ entry = STMMAC_GET_ENTRY(entry, DMA_TX_SIZE);
desc = priv->dma_tx + entry;
if (len > bmax) {
@@ -82,6 +81,9 @@
len = 0;
}
}
+
+ priv->cur_tx = entry;
+
return entry;
}
@@ -138,7 +140,7 @@
*/
p->des3 = (unsigned int)(priv->dma_rx_phy +
(((priv->dirty_rx) + 1) %
- priv->dma_rx_size) *
+ DMA_RX_SIZE) *
sizeof(struct dma_desc));
}
@@ -151,10 +153,9 @@
* 1588-2002 time stamping is enabled, hence reinitialize it
* to keep explicit chaining in the descriptor.
*/
- p->des3 = (unsigned int)(priv->dma_tx_phy +
- (((priv->dirty_tx + 1) %
- priv->dma_tx_size) *
- sizeof(struct dma_desc)));
+ p->des3 = (unsigned int)((priv->dma_tx_phy +
+ ((priv->dirty_tx + 1) % DMA_TX_SIZE))
+ * sizeof(struct dma_desc));
}
const struct stmmac_mode_ops chain_mode_ops = {