staging: fsl-dpaa2/eth: Make Tx buffer alignment optional

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@nxp.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/staging/fsl-dpaa2/ethernet/dpaa2-eth.c b/drivers/staging/fsl-dpaa2/ethernet/dpaa2-eth.c
index 8edb7c10f978cd0768a71761aff7646100a1f3b4..7f3e4fae6bb9e6ac95973da7f3f4022bfb733225 100644 (file)
--- 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 4ea41d85c231803fe2f1658c7fb3759023347e05..d68ac386dd0aa54aa9ceafc87672c86bf96df4fd 100644 (file)
--- 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