Re: [PATCH net-next v5 13/14] xsc: Add eth reception data path

[Joe Damato <jdamato@fastly.com>]

On Tue, Feb 25, 2025 at 01:24:44AM +0800, Xin Tian wrote:
> rx data path:

[...]

> diff --git a/drivers/net/ethernet/yunsilicon/xsc/net/xsc_eth_rx.c b/drivers/net/ethernet/yunsilicon/xsc/net/xsc_eth_rx.c
> index 72f33bb53..b87105c26 100644
> --- a/drivers/net/ethernet/yunsilicon/xsc/net/xsc_eth_rx.c
> +++ b/drivers/net/ethernet/yunsilicon/xsc/net/xsc_eth_rx.c
> @@ -5,44 +5,594 @@

[...]

>  struct sk_buff *xsc_skb_from_cqe_linear(struct xsc_rq *rq,
>  					struct xsc_wqe_frag_info *wi,
>  					u32 cqe_bcnt, u8 has_pph)
>  {
> -	// TBD
> -	return NULL;
> +	int pph_len = has_pph ? XSC_PPH_HEAD_LEN : 0;
> +	u16 rx_headroom = rq->buff.headroom;
> +	struct xsc_dma_info *di = wi->di;
> +	struct sk_buff *skb;
> +	void *va, *data;
> +	u32 frag_size;
> +
> +	va = page_address(di->page) + wi->offset;
> +	data = va + rx_headroom + pph_len;
> +	frag_size = XSC_SKB_FRAG_SZ(rx_headroom + cqe_bcnt);
> +
> +	dma_sync_single_range_for_cpu(rq->cq.xdev->device, di->addr, wi->offset,
> +				      frag_size, DMA_FROM_DEVICE);
> +	prefetchw(va); /* xdp_frame data area */
> +	prefetch(data);

net_prefetchw and net_prefetch, possibly?

[...]

>  struct sk_buff *xsc_skb_from_cqe_nonlinear(struct xsc_rq *rq,
>  					   struct xsc_wqe_frag_info *wi,
>  					   u32 cqe_bcnt, u8 has_pph)
>  {
> -	// TBD
> -	return NULL;
> +	struct xsc_rq_frag_info *frag_info = &rq->wqe.info.arr[0];
> +	u16 headlen  = min_t(u32, XSC_RX_MAX_HEAD, cqe_bcnt);
> +	struct xsc_wqe_frag_info *head_wi = wi;
> +	struct xsc_wqe_frag_info *rx_wi = wi;
> +	u16 head_offset = head_wi->offset;
> +	u16 byte_cnt = cqe_bcnt - headlen;
> +	u16 frag_consumed_bytes = 0;
> +	u16 frag_headlen = headlen;
> +	struct net_device *netdev;
> +	struct xsc_channel *c;
> +	struct sk_buff *skb;
> +	struct device *dev;
> +	u8 fragcnt = 0;
> +	int i = 0;
> +
> +	c = rq->cq.channel;
> +	dev = c->adapter->dev;
> +	netdev = c->adapter->netdev;
> +
> +	skb = napi_alloc_skb(rq->cq.napi, ALIGN(XSC_RX_MAX_HEAD, sizeof(long)));
> +	if (unlikely(!skb))
> +		return NULL;
> +
> +	prefetchw(skb->data);

Same as above: net_prefetchw ?