netdev - Re: [PATCH net-next 3/3] net: stmmac: Introducing support for Page Pool

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Date:   Thu, 4 Jul 2019 11:48:04 +0200
From:   Jesper Dangaard Brouer <brouer@...hat.com>
To:     Jose Abreu <Jose.Abreu@...opsys.com>
Cc:     brouer@...hat.com, linux-kernel@...r.kernel.org,
        netdev@...r.kernel.org, linux-stm32@...md-mailman.stormreply.com,
        linux-arm-kernel@...ts.infradead.org,
        Joao Pinto <Joao.Pinto@...opsys.com>,
        "David S . Miller" <davem@...emloft.net>,
        Giuseppe Cavallaro <peppe.cavallaro@...com>,
        Alexandre Torgue <alexandre.torgue@...com>,
        Maxime Coquelin <mcoquelin.stm32@...il.com>,
        Maxime Ripard <maxime.ripard@...tlin.com>,
        Chen-Yu Tsai <wens@...e.org>,
        Ilias Apalodimas <ilias.apalodimas@...aro.org>
Subject: Re: [PATCH net-next 3/3] net: stmmac: Introducing support for Page
 Pool

On Wed,  3 Jul 2019 12:37:50 +0200
Jose Abreu <Jose.Abreu@...opsys.com> wrote:

> --- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
> +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
> @@ -1197,26 +1197,14 @@ static int stmmac_init_rx_buffers(struct stmmac_priv *priv, struct dma_desc *p,
>  				  int i, gfp_t flags, u32 queue)
>  {
>  	struct stmmac_rx_queue *rx_q = &priv->rx_queue[queue];
> -	struct sk_buff *skb;
> +	struct stmmac_rx_buffer *buf = &rx_q->buf_pool[i];
>  
> -	skb = __netdev_alloc_skb_ip_align(priv->dev, priv->dma_buf_sz, flags);
> -	if (!skb) {
> -		netdev_err(priv->dev,
> -			   "%s: Rx init fails; skb is NULL\n", __func__);
> +	buf->page = page_pool_dev_alloc_pages(rx_q->page_pool);
> +	if (!buf->page)
>  		return -ENOMEM;
> -	}
> -	rx_q->rx_skbuff[i] = skb;
> -	rx_q->rx_skbuff_dma[i] = dma_map_single(priv->device, skb->data,
> -						priv->dma_buf_sz,
> -						DMA_FROM_DEVICE);
> -	if (dma_mapping_error(priv->device, rx_q->rx_skbuff_dma[i])) {
> -		netdev_err(priv->dev, "%s: DMA mapping error\n", __func__);
> -		dev_kfree_skb_any(skb);
> -		return -EINVAL;
> -	}
> -
> -	stmmac_set_desc_addr(priv, p, rx_q->rx_skbuff_dma[i]);
>  
> +	buf->addr = buf->page->dma_addr;

We/Ilias added a wrapper/helper function for accessing dma_addr, as it
will help us later identifying users.

 page_pool_get_dma_addr(page)

> +	stmmac_set_desc_addr(priv, p, buf->addr);
>  	if (priv->dma_buf_sz == BUF_SIZE_16KiB)
>  		stmmac_init_desc3(priv, p);
>  


-- 
Best regards,
  Jesper Dangaard Brouer
  MSc.CS, Principal Kernel Engineer at Red Hat
  LinkedIn: http://www.linkedin.com/in/brouer