From c163685fc886037b83e27cfc1d9efffd00e7a5bf Mon Sep 17 00:00:00 2001 From: Ioana Radulescu Date: Fri, 8 Dec 2017 06:47:58 -0600 Subject: [PATCH] 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 Signed-off-by: Greg Kroah-Hartman --- 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 8edb7c10f978..7f3e4fae6bb9 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 4ea41d85c231..d68ac386dd0a 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