Subject: Re: [PATCH 11/12] FEC Buffer rework

From: Greg Ungerer <[email-masked]>
Date: Fri, 17 Apr 2009 20:07:26 +1000

Hi Sascha,

Sascha Hauer wrote:
> Allocate buffers in fec_open and free them again in fec_close. This makes
> it possible to use this driver as a module.
> 
> Signed-off-by: Sascha Hauer <[email-masked]>

This is the only one that doesn't work for ColdFire. There is no
dma_map_single() or dma_unmap_single() currently. I will fix that,
so I am fine with this anyways.

With all the other patches applied it still basically works on ColdFire
(at least on initial testing on a 5208). I have seen a few spurious
interrupts though with these changes applied, that didn't happen
before. I will investigate further when get a few minutes.

Regards
Greg

> ---
>  drivers/net/fec.c |  139 +++++++++++++++++++++++++++++++++-------------------
>  1 files changed, 88 insertions(+), 51 deletions(-)
> 
> diff --git a/drivers/net/fec.c b/drivers/net/fec.c
> index f4afbe9..0e1d268 100644
> --- a/drivers/net/fec.c
> +++ b/drivers/net/fec.c
> @@ -172,6 +172,7 @@ struct fec_enet_private {
>  	/* The saved address of a sent-in-place packet/buffer, for skfree(). */
>  	unsigned char *tx_bounce[TX_RING_SIZE];
>  	struct	sk_buff* tx_skbuff[TX_RING_SIZE];
> +	struct	sk_buff* rx_skbuff[RX_RING_SIZE];
>  	ushort	skb_cur;
>  	ushort	skb_dirty;
>  
> @@ -335,8 +336,8 @@ fec_enet_start_xmit(struct sk_buff *skb, struct net_device *dev)
>  	/* Push the data cache so the CPM does not get stale memory
>  	 * data.
>  	 */
> -	dma_sync_single(NULL, bdp->cbd_bufaddr,
> -			bdp->cbd_datlen, DMA_TO_DEVICE);
> +	bdp->cbd_bufaddr = dma_map_single(&dev->dev, skb->data,
> +			FEC_ENET_TX_FRSIZE, DMA_TO_DEVICE);
>  
>  	/* Send it on its way.  Tell FEC it's ready, interrupt when done,
>  	 * it's the last BD of the frame, and to put the CRC on the end.
> @@ -429,7 +430,11 @@ fec_enet_tx(struct net_device *dev)
>  	bdp = fep->dirty_tx;
>  
>  	while (((status = bdp->cbd_sc) & BD_ENET_TX_READY) == 0) {
> -		if (bdp == fep->cur_tx && fep->tx_full == 0) break;
> +		if (bdp == fep->cur_tx && fep->tx_full == 0)
> +			break;
> +
> +		dma_unmap_single(&dev->dev, bdp->cbd_bufaddr, FEC_ENET_TX_FRSIZE, DMA_TO_DEVICE);
> +		bdp->cbd_bufaddr = 0;
>  
>  		skb = fep->tx_skbuff[fep->skb_dirty];
>  		/* Check for errors. */
> @@ -553,8 +558,8 @@ fec_enet_rx(struct net_device *dev)
>  		dev->stats.rx_bytes += pkt_len;
>  		data = (__u8*)__va(bdp->cbd_bufaddr);
>  
> -		dma_sync_single(NULL, (unsigned long)__pa(data),
> -			pkt_len - 4, DMA_FROM_DEVICE);
> +	        dma_unmap_single(NULL, bdp->cbd_bufaddr, bdp->cbd_datlen,
> +        			DMA_FROM_DEVICE);
>  
>  		/* This does 16 byte alignment, exactly what we need.
>  		 * The packet length includes FCS, but we don't want to
> @@ -574,6 +579,9 @@ fec_enet_rx(struct net_device *dev)
>  			skb->protocol = eth_type_trans(skb, dev);
>  			netif_rx(skb);
>  		}
> +
> +        	bdp->cbd_bufaddr = dma_map_single(NULL, data, bdp->cbd_datlen,
> +			DMA_FROM_DEVICE);
>  rx_processing_done:
>  		/* Clear the status flags for this buffer */
>  		status &= ~BD_ENET_RX_STATS;
> @@ -1399,15 +1407,86 @@ mii_link_interrupt(int irq, void * dev_id)
>  }
>  #endif
>  
> +static void fec_enet_free_buffers(struct net_device *dev)
> +{
> +	struct fec_enet_private *fep = netdev_priv(dev);
> +	int i;
> +	struct sk_buff *skb;
> +	struct bufdesc	*bdp;
> +
> +	bdp = fep->rx_bd_base;
> +	for (i = 0; i < RX_RING_SIZE; i++) {
> +		skb = fep->rx_skbuff[i];
> +
> +		if (bdp->cbd_bufaddr)
> +			dma_unmap_single(&dev->dev, bdp->cbd_bufaddr,
> +					FEC_ENET_RX_FRSIZE, DMA_FROM_DEVICE);
> +		if (skb)
> +			dev_kfree_skb(skb);
> +		bdp++;
> +	}
> +
> +	bdp = fep->tx_bd_base;
> +	for (i = 0; i < TX_RING_SIZE; i++)
> +		kfree(fep->tx_bounce[i]);
> +}
> +
> +static int fec_enet_alloc_buffers(struct net_device *dev)
> +{
> +	struct fec_enet_private *fep = netdev_priv(dev);
> +	int i;
> +	struct sk_buff *skb;
> +	struct bufdesc	*bdp;
> +
> +	bdp = fep->rx_bd_base;
> +	for (i = 0; i < RX_RING_SIZE; i++) {
> +		skb = dev_alloc_skb(FEC_ENET_RX_FRSIZE);
> +		if (!skb) {
> +			fec_enet_free_buffers(dev);
> +			return -ENOMEM;
> +		}
> +		fep->rx_skbuff[i] = skb;
> +
> +		bdp->cbd_bufaddr = dma_map_single(&dev->dev, skb->data,
> +				FEC_ENET_RX_FRSIZE, DMA_FROM_DEVICE);
> +		bdp->cbd_sc = BD_ENET_RX_EMPTY;
> +		bdp++;
> +	}
> +
> +	/* Set the last buffer to wrap. */
> +	bdp--;
> +	bdp->cbd_sc |= BD_SC_WRAP;
> +
> +	bdp = fep->tx_bd_base;
> +	for (i = 0; i < TX_RING_SIZE; i++) {
> +		fep->tx_bounce[i] = kmalloc(FEC_ENET_TX_FRSIZE, GFP_KERNEL);
> +
> +		bdp->cbd_sc = 0;
> +		bdp->cbd_bufaddr = 0;
> +		bdp++;
> +	}
> +
> +	/* Set the last buffer to wrap. */
> +	bdp--;
> +	bdp->cbd_sc |= BD_SC_WRAP;
> +
> +	return 0;
> +}
> +
>  static int
>  fec_enet_open(struct net_device *dev)
>  {
>  	struct fec_enet_private *fep = netdev_priv(dev);
> +	int ret;
>  
>  	/* I should reset the ring buffers here, but I don't yet know
>  	 * a simple way to do that.
>  	 */
>  
> +	ret = fec_enet_alloc_buffers(dev);
> +	if (ret)
> +		return ret;
> +
>  	fep->sequence_done = 0;
>  	fep->link = 0;
>  
> @@ -1454,6 +1533,8 @@ fec_enet_close(struct net_device *dev)
>  	netif_stop_queue(dev);
>  	fec_stop(dev);
>  
> +        fec_enet_free_buffers(dev);
> +
>  	return 0;
>  }
>  
> @@ -1576,9 +1657,8 @@ static const struct net_device_ops fec_netdev_ops = {
>  int __init fec_enet_init(struct net_device *dev, int index)
>  {
>  	struct fec_enet_private *fep = netdev_priv(dev);
> -	unsigned long	mem_addr;
> -	struct bufdesc *bdp, *cbd_base;
> -	int 		i, j;
> +	struct bufdesc *cbd_base;
> +	int i;
>  
>  	/* Allocate memory for buffer descriptors. */
>  	cbd_base = dma_alloc_coherent(NULL, PAGE_SIZE, &fep->bd_dma,
> @@ -1616,49 +1696,6 @@ int __init fec_enet_init(struct net_device *dev, int index)
>  	fep->rx_bd_base = cbd_base;
>  	fep->tx_bd_base = cbd_base + RX_RING_SIZE;
>  
> -	/* Initialize the receive buffer descriptors. */
> -	bdp = fep->rx_bd_base;
> -	for (i=0; i<FEC_ENET_RX_PAGES; i++) {
> -
> -		/* Allocate a page */
> -		mem_addr = __get_free_page(GFP_KERNEL);
> -		/* XXX: missing check for allocation failure */
> -
> -		/* Initialize the BD for every fragment in the page */
> -		for (j=0; j<FEC_ENET_RX_FRPPG; j++) {
> -			bdp->cbd_sc = BD_ENET_RX_EMPTY;
> -			bdp->cbd_bufaddr = __pa(mem_addr);
> -			mem_addr += FEC_ENET_RX_FRSIZE;
> -			bdp++;
> -		}
> -	}
> -
> -	/* Set the last buffer to wrap */
> -	bdp--;
> -	bdp->cbd_sc |= BD_SC_WRAP;
> -
> -	/* ...and the same for transmit */
> -	bdp = fep->tx_bd_base;
> -	for (i=0, j=FEC_ENET_TX_FRPPG; i<TX_RING_SIZE; i++) {
> -		if (j >= FEC_ENET_TX_FRPPG) {
> -			mem_addr = __get_free_page(GFP_KERNEL);
> -			j = 1;
> -		} else {
> -			mem_addr += FEC_ENET_TX_FRSIZE;
> -			j++;
> -		}
> -		fep->tx_bounce[i] = (unsigned char *) mem_addr;
> -
> -		/* Initialize the BD for every fragment in the page */
> -		bdp->cbd_sc = 0;
> -		bdp->cbd_bufaddr = 0;
> -		bdp++;
> -	}
> -
> -	/* Set the last buffer to wrap */
> -	bdp--;
> -	bdp->cbd_sc |= BD_SC_WRAP;
> -
>  #ifdef HAVE_mii_link_interrupt
>  	fec_request_mii_intr(dev);
>  #endif

-- 
------------------------------------------------------------------------
Greg Ungerer  --  Principal Engineer        EMAIL:     [email-masked]
SnapGear Group, McAfee                      PHONE:       +61 7 3435 2888
825 Stanley St,                             FAX:         +61 7 3891 3630
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