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dpaa2-eth: increase the needed headroom to account for alignment

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[ Upstream commit f422abe3f23d483cf01f386819f26fb3fe0dbb2b ]

Increase the needed headroom to account for a 64 byte alignment
restriction which, with this patch, we make mandatory on the Tx path.
The case in which the amount of headroom needed is not available is
already handled by the driver which instead sends a S/G frame with the
first buffer only holding the SW and HW annotation areas.

Without this patch, we can empirically see data corruption happening
between Tx and Tx confirmation which sometimes leads to the SW
annotation area being overwritten.

Since this is an old IP where the hardware team cannot help to
understand the underlying behavior, we make the Tx alignment mandatory
for all frames to avoid the crash on Tx conf. Also, remove the comment
that suggested that this is just an optimization.

This patch also sets the needed_headroom net device field to the usual
value that the driver would need on the Tx path:
	- 64 bytes for the software annotation area
	- 64 bytes to account for a 64 byte aligned buffer address

Fixes: 6e2387e8f19e ("staging: fsl-dpaa2/eth: Add Freescale DPAA2 Ethernet driver")
Closes: https://lore.kernel.org/netdev/aa784d0c-85eb-4e5d-968b-c8f74fa86be6@gin.de/
Signed-off-by: Ioana Ciornei <ioana.ciornei@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Ioana Ciornei 2023-11-24 12:28:04 +02:00 committed by Greg Kroah-Hartman
parent 94445d9583
commit fd91b48f10
2 changed files with 5 additions and 5 deletions
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8
drivers/net/ethernet/freescale/dpaa2/dpaa2-eth.c
View File

@ -1043,14 +1043,12 @@ static int dpaa2_eth_build_single_fd(struct dpaa2_eth_priv *priv,
dma_addr_t addr;
buffer_start = skb->data - dpaa2_eth_needed_headroom(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;
else
return -ENOMEM;
/* Store a backpointer to the skb at the beginning of the buffer
* (in the private data area) such that we can release it
@ -4738,6 +4736,8 @@ static int dpaa2_eth_probe(struct fsl_mc_device *dpni_dev)
if (err)
goto err_dl_port_add;
net_dev->needed_headroom = DPAA2_ETH_SWA_SIZE + DPAA2_ETH_TX_BUF_ALIGN;
err = register_netdev(net_dev);
if (err < 0) {
dev_err(dev, "register_netdev() failed\n");

2
drivers/net/ethernet/freescale/dpaa2/dpaa2-eth.h
View File

@ -702,7 +702,7 @@ static inline bool dpaa2_eth_rx_pause_enabled(u64 link_options)
static inline unsigned int dpaa2_eth_needed_headroom(struct sk_buff *skb)
{
unsigned int headroom = DPAA2_ETH_SWA_SIZE;
unsigned int headroom = DPAA2_ETH_SWA_SIZE + DPAA2_ETH_TX_BUF_ALIGN;
/* If we don't have an skb (e.g. XDP buffer), we only need space for
* the software annotation area