[LEDE-DEV] [PATCH] ag71xx: Add some unlikely calls + rearange some stuff in hard_start_xmit.

[Felix Fietkau]

On 2018-02-13 23:53, Rosen Penev wrote:
> Based on Qualcomm driver. Improves iperf3 throughput by ~20mbps on transmit on Archer C7v4.
> 
> Signed-off-by: Rosen Penev <rosenp at gmail.com>
> ---
>  .../drivers/net/ethernet/atheros/ag71xx/ag71xx_main.c      | 14 +++++++-------
>  1 file changed, 7 insertions(+), 7 deletions(-)
> 
> diff --git a/target/linux/ar71xx/files/drivers/net/ethernet/atheros/ag71xx/ag71xx_main.c b/target/linux/ar71xx/files/drivers/net/ethernet/atheros/ag71xx/ag71xx_main.c
> index 95682b7641..d32f220178 100644
> --- a/target/linux/ar71xx/files/drivers/net/ethernet/atheros/ag71xx/ag71xx_main.c
> +++ b/target/linux/ar71xx/files/drivers/net/ethernet/atheros/ag71xx/ag71xx_main.c
> @@ -797,11 +797,14 @@ static netdev_tx_t ag71xx_hard_start_xmit(struct sk_buff *skb,
>  	if (ag71xx_has_ar8216(ag))
>  		ag71xx_add_ar8216_header(ag, skb);
>  
> -	if (skb->len <= 4) {
> +	dma_cache_sync (NULL, skb->data, skb->len, DMA_TO_DEVICE);
The use of dma_cache_sync here makes no sense, since it's the wrong API.
Also, effectively it results in the same kind of cache flush as the one
that's done by the DMA mapping done later.

- Felix