On Fri, Apr 25, 2014 at 6:13 AM, Mark Salter <msalter@xxxxxxxxxx> wrote:
> On Wed, 2014-04-16 at 19:39 -0700, Iyappan Subramanian wrote:
>> +static int xgene_enet_refill_bufpool(struct xgene_enet_desc_ring *buf_pool,
>> + u32 nbuf)
>> +{
>> + struct sk_buff *skb;
>> + struct xgene_enet_desc16 *desc;
>> + struct net_device *ndev;
>> + struct device *dev;
>> + dma_addr_t dma_addr;
>> + u32 tail = buf_pool->tail;
>> + u32 slots = buf_pool->slots - 1;
>> + int i, ret = 0;
>> + u16 bufdatalen = BUF_LEN_CODE_2K | (SKB_BUFFER_SIZE & GENMASK(11, 0));
>> +
>> + ndev = buf_pool->ndev;
>> + dev = ndev_to_dev(buf_pool->ndev);
>> +
>> + for (i = 0; i < nbuf; i++) {
>> + desc = &buf_pool->desc16[tail];
>> +
>> + skb = netdev_alloc_skb_ip_align(ndev, XGENE_ENET_MAX_MTU);
>> + if (unlikely(!skb)) {
>> + netdev_err(ndev, "Could not allocate skb");
>> + ret = -ENOMEM;
>> + goto out;
>> + }
>> + buf_pool->rx_skb[tail] = skb;
>> +
>> + dma_addr = dma_map_single(dev, skb->data, skb->len,
>> + DMA_TO_DEVICE);
>
> Shouldn't this be:
>
> dma_addr = dma_map_single(dev, skb->data, XGENE_ENET_MAX_MTU,
> DMA_TO_DEVICE);
>
> You just allocated the skb and nothing is in it, so ->len is zero.
Thanks Mark. I will fix the code.
>
>> +
>> +static int xgene_enet_rx_frame(struct xgene_enet_desc_ring *rx_ring,
>> + struct xgene_enet_desc *desc)
>> +{
>> + struct net_device *ndev = rx_ring->ndev;
>> + struct device *dev = ndev_to_dev(rx_ring->ndev);
>> + struct xgene_enet_desc_ring *buf_pool = rx_ring->buf_pool;
>> + u32 datalen, skb_index;
>> + struct sk_buff *skb;
>> + dma_addr_t pa;
>> + size_t len;
>> + int ret = 0;
>> +
>> + skb_index = get_desc(desc, USERINFO);
>> + skb = buf_pool->rx_skb[skb_index];
>> + prefetch(skb->data - NET_IP_ALIGN);
>> +
>> + /* Strip off CRC as HW isn't doing this */
>> + datalen = get_desc(desc, BUFDATALEN);
>> + datalen -= 4;
>> + skb_put(skb, datalen);
>> +
>> + pa = (dma_addr_t)get_desc(desc, DATAADDR);
>> + len = get_desc(desc, BUFDATALEN);
>> + dma_unmap_single(dev, pa, len, DMA_TO_DEVICE);
>> +
>
> And here, should be:
>
> dma_unmap_single(dev, pa, XGENE_ENET_MAX_MTU, DMA_TO_DEVICE);
>
> You want to unmap the whole buffer, not just the part actually used.
>
> The underlying code works with pages, so the existing code may work by
> chance, but you get err_printks is you turn on dma debug.
I will fix the code. DMA_API_DEBUG option is very handy. Thanks.
>
> --Mark
>
>
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