netdev - Re: [PATCH v8] bfin_mac: convert bfin Ethernet driver to NAPI framework

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Message-ID: <1406193211.3363.69.camel@edumazet-glaptop2.roam.corp.google.com>
Date:	Thu, 24 Jul 2014 11:13:31 +0200
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	Sonic Zhang <sonic.adi@...il.com>
Cc:	"David S. Miller" <davem@...emloft.net>, netdev@...r.kernel.org,
	Francois Romieu <romieu@...zoreil.com>,
	adi-buildroot-devel@...ts.sourceforge.net,
	Sonic Zhang <sonic.zhang@...log.com>
Subject: Re: [PATCH v8] bfin_mac: convert bfin Ethernet driver to NAPI
 framework

On Thu, 2014-07-24 at 16:39 +0800, Sonic Zhang wrote:
> From: Sonic Zhang <sonic.zhang@...log.com>
> 
> Ethernet RX DMA buffers are polled in NAPI work queue other than received
> directly in DMA RX interrupt handler.
> 


> ---
>  drivers/net/ethernet/adi/bfin_mac.c | 79 +++++++++++++++++++++++--------------
>  drivers/net/ethernet/adi/bfin_mac.h |  3 ++
>  2 files changed, 52 insertions(+), 30 deletions(-)
> 
> diff --git a/drivers/net/ethernet/adi/bfin_mac.c b/drivers/net/ethernet/adi/bfin_mac.c
> index 7ae74d4..c1f04aa 100644
> --- a/drivers/net/ethernet/adi/bfin_mac.c
> +++ b/drivers/net/ethernet/adi/bfin_mac.c
> @@ -1218,11 +1218,11 @@ out:
>  #define RX_ERROR_MASK (RX_LONG | RX_ALIGN | RX_CRC | RX_LEN | \
>  	RX_FRAG | RX_ADDR | RX_DMAO | RX_PHY | RX_LATE | RX_RANGE)
>  
> -static void bfin_mac_rx(struct net_device *dev)
> +static void bfin_mac_rx(struct bfin_mac_local *lp, int budget)

budget is not used in this function. (I already mentioned this)

>  {
> +	struct net_device *dev = lp->ndev;
>  	struct sk_buff *skb, *new_skb;
>  	unsigned short len;
> -	struct bfin_mac_local *lp __maybe_unused = netdev_priv(dev);
>  #if defined(BFIN_MAC_CSUM_OFFLOAD)
>  	unsigned int i;
>  	unsigned char fcs[ETH_FCS_LEN + 1];
> @@ -1256,7 +1256,7 @@ static void bfin_mac_rx(struct net_device *dev)
>  	current_rx_ptr->skb = new_skb;
>  	current_rx_ptr->desc_a.start_addr = (unsigned long)new_skb->data - 2;
>  
> -	len = (unsigned short)((current_rx_ptr->status.status_word) & RX_FRLEN);
> +	len = (unsigned short)(current_rx_ptr->status.status_word & RX_FRLEN);
>  	/* Deduce Ethernet FCS length from Ethernet payload length */
>  	len -= ETH_FCS_LEN;
>  	skb_put(skb, len);
> @@ -1294,7 +1294,8 @@ static void bfin_mac_rx(struct net_device *dev)
>  	}
>  #endif
>  
> -	netif_rx(skb);
> +	napi_gro_receive(&lp->napi, skb);
> +
>  	dev->stats.rx_packets++;
>  	dev->stats.rx_bytes += len;
>  out:
> @@ -1302,41 +1303,52 @@ out:
>  	current_rx_ptr = current_rx_ptr->next;
>  }


> +	if ((status & DMA_DONE)) {
> +		disable_irq_nosync(IRQ_MAC_RX);
> +		set_bit(BFIN_MAC_RX_IRQ_DISABLED, &lp->flags);
> +		napi_schedule(&lp->napi);
>  	}

	No need for extra ()

	if (status & DMA_DONE) {
		...



>+       netif_napi_add(ndev, &lp->napi, bfin_mac_poll, CONFIG_BFIN_RX_DESC_NUM);


I already gave a feedback on this. Could you address it ?

Have you checked kernel log ?

You should have hit :

        if (weight > NAPI_POLL_WEIGHT)
                pr_err_once("netif_napi_add() called with weight %d on device %s\n",
                            weight, dev->name);

This is because CONFIG_BFIN_RX_DESC_NUM is 100, while NAPI_POLL_WEIGHT is 64.



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