Aligning the Tx buffers at 64B is a performance optimization
recommendation, not a hard requirement.
Make optional the alignment of Tx FD buffers, without enforcing
a reallocation in case there is not enough headroom for it.
On Rx, we keep allocating buffers with enough headroom to allow
Tx alignment of forwarded frames.
Signed-off-by: Ioana Radulescu <ruxandra.radulescu@xxxxxxx>
---
drivers/staging/fsl-dpaa2/ethernet/dpaa2-eth.c | 14 ++++++++++----
drivers/staging/fsl-dpaa2/ethernet/dpaa2-eth.h | 2 +-
2 files changed, 11 insertions(+), 5 deletions(-)
diff --git a/drivers/staging/fsl-dpaa2/ethernet/dpaa2-eth.c b/drivers/staging/fsl-dpaa2/ethernet/dpaa2-eth.c
index 8edb7c1..7f3e4fa 100644
--- a/drivers/staging/fsl-dpaa2/ethernet/dpaa2-eth.c
+++ b/drivers/staging/fsl-dpaa2/ethernet/dpaa2-eth.c
@@ -433,13 +433,19 @@ static int build_single_fd(struct dpaa2_eth_priv *priv,
struct dpaa2_fd *fd)
{
struct device *dev = priv->net_dev->dev.parent;
- u8 *buffer_start;
+ u8 *buffer_start, *aligned_start;
struct sk_buff **skbh;
dma_addr_t addr;
- buffer_start = PTR_ALIGN(skb->data -
- dpaa2_eth_needed_headroom(priv, skb),
- DPAA2_ETH_TX_BUF_ALIGN);
+ buffer_start = skb->data - dpaa2_eth_needed_headroom(priv, skb);
+
+ /* If there's enough room to align the FD address, do it.
+ * It will help hardware optimize accesses.
+ */
+ aligned_start = PTR_ALIGN(buffer_start - DPAA2_ETH_TX_BUF_ALIGN,
+ DPAA2_ETH_TX_BUF_ALIGN);
+ if (aligned_start >= skb->head)
+ buffer_start = aligned_start;
/* Store a backpointer to the skb at the beginning of the buffer
* (in the private data area) such that we can release it
diff --git a/drivers/staging/fsl-dpaa2/ethernet/dpaa2-eth.h b/drivers/staging/fsl-dpaa2/ethernet/dpaa2-eth.h
index 4ea41d8..d68ac38 100644
--- a/drivers/staging/fsl-dpaa2/ethernet/dpaa2-eth.h
+++ b/drivers/staging/fsl-dpaa2/ethernet/dpaa2-eth.h
@@ -370,7 +370,7 @@ unsigned int dpaa2_eth_needed_headroom(struct dpaa2_eth_priv *priv,
if (skb_is_nonlinear(skb))
return 0;
- return DPAA2_ETH_SWA_SIZE + DPAA2_ETH_TX_BUF_ALIGN;
+ return DPAA2_ETH_SWA_SIZE;
}
/* Extra headroom space requested to hardware, in order to make sure there's
--
2.7.4
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