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Message-ID: <20071025185706.29496.qmail@farnsworth.org>
Date: 25 Oct 2007 11:57:06 -0700
From: "Dale Farnsworth" <dale@...nsworth.org>
To: domen.puncer@...argo.com
Cc: netdev@...r.kernel.org, linuxppc-dev@...abs.org
Subject: Re: [PATCH v4] FEC - fast ethernet controller for mpc52xx
Domen wrote:
> > use your platform's dma mapping functions, rather than virt_to_phys()
> >
> > it might be the exact same implementation, inside the platform
> > internals, but drivers should not be using this directly.
>
> I've replaced this with dma_map_single(), unmatched with
> dma_unmap_single(), since bestcomm doesn't have a way to do that
> and it's blank on ppc32 anyway.
>
> Is this OK? PPC guys?
Even though dma_unmap_single() may be a no-op, calls to
dma_map_single() must be matched with calls to dma_unmap_single().
Perhaps with the additions below:
> +static void mpc52xx_fec_free_rx_buffers(struct bcom_task *s)
> +{
> + struct sk_buff *skb;
> +
> + while (!bcom_queue_empty(s)) {
> + skb = bcom_retrieve_buffer(s, NULL, NULL);
dma_unmap_single(&skb->dev->dev, skb-data,
FEC_RX_BUFFER_SIZE, DMA_FROM_DEVICE);
> + kfree_skb(skb);
> + }
> +}
> +
> +static int mpc52xx_fec_alloc_rx_buffers(struct net_device *dev, struct
> bcom_task *rxtsk)
> +{
> + while (!bcom_queue_full(rxtsk)) {
> + struct sk_buff *skb;
> + struct bcom_fec_bd *bd;
> +
> + skb = dev_alloc_skb(FEC_RX_BUFFER_SIZE);
> + if (skb == NULL)
> + return -EAGAIN;
skb->dev = dev;
> +
> + /* zero out the initial receive buffers to aid debugging */
> + memset(skb->data, 0, FEC_RX_BUFFER_SIZE);
> +
> + bd = (struct bcom_fec_bd *)bcom_prepare_next_buffer(rxtsk);
> +
> + bd->status = FEC_RX_BUFFER_SIZE;
> + bd->skb_pa = dma_map_single(&dev->dev, skb->data,
> + FEC_RX_BUFFER_SIZE, DMA_FROM_DEVICE);
> +
> + bcom_submit_next_buffer(rxtsk, skb);
> + }
> +
> + return 0;
> +}
[...]
> +static int mpc52xx_fec_hard_start_xmit(struct sk_buff *skb, struct
> net_device *dev)
> +{
> + struct mpc52xx_fec_priv *priv = netdev_priv(dev);
> + struct bcom_fec_bd *bd;
> +
> + if (bcom_queue_full(priv->tx_dmatsk)) {
> + if (net_ratelimit())
> + dev_err(&dev->dev, "transmit queue overrun\n");
> + return 1;
> + }
> +
> + spin_lock_irq(&priv->lock);
> + dev->trans_start = jiffies;
> +
> + bd = (struct bcom_fec_bd *)
> + bcom_prepare_next_buffer(priv->tx_dmatsk);
> +
> + bd->status = skb->len | BCOM_FEC_TX_BD_TFD | BCOM_FEC_TX_BD_TC;
> + bd->skb_pa = dma_map_single(&dev->dev, skb->data, skb->len, DMA_TO_DEVICE);
> +
> + bcom_submit_next_buffer(priv->tx_dmatsk, skb);
> +
> + if (bcom_queue_full(priv->tx_dmatsk)) {
> + netif_stop_queue(dev);
> + }
> +
> + spin_unlock_irq(&priv->lock);
> +
> + return 0;
> +}
> +
> +/* This handles BestComm transmit task interrupts
> + */
> +static irqreturn_t mpc52xx_fec_tx_interrupt(int irq, void *dev_id)
> +{
> + struct net_device *dev = dev_id;
> + struct mpc52xx_fec_priv *priv = netdev_priv(dev);
> +
> + spin_lock(&priv->lock);
> +
> + while (bcom_buffer_done(priv->tx_dmatsk)) {
> + struct sk_buff *skb;
> + skb = bcom_retrieve_buffer(priv->tx_dmatsk, NULL, NULL);
> + /* Here (and in rx routines) would be a good place for
> + * dma_unmap_single(), but bcom doesn't return bcom_bd of the
> + * finished transfer, and _unmap is empty on this platfrom.
> + */
Replace the above comment with:
dma_unmap_single(&dev->dev, skb->data,
skb->len, DMA_TO_DEVICE);
> +
> + dev_kfree_skb_irq(skb);
> + }
> +
> + netif_wake_queue(dev);
> +
> + spin_unlock(&priv->lock);
> +
> + return IRQ_HANDLED;
> +}
> +
> +static irqreturn_t mpc52xx_fec_rx_interrupt(int irq, void *dev_id)
> +{
> + struct net_device *dev = dev_id;
> + struct mpc52xx_fec_priv *priv = netdev_priv(dev);
> +
> + while (bcom_buffer_done(priv->rx_dmatsk)) {
> + struct sk_buff *skb;
> + struct sk_buff *rskb;
> + struct bcom_fec_bd *bd;
> + u32 status;
> +
> + rskb = bcom_retrieve_buffer(priv->rx_dmatsk, &status, NULL);
dma_unmap_single(&dev->dev, rskb->data,
FEC_RX_BUFFER_SIZE, DMA_FROM_DEVICE);
> +
> + /* Test for errors in received frame */
> + if (status & BCOM_FEC_RX_BD_ERRORS) {
> + /* Drop packet and reuse the buffer */
> + bd = (struct bcom_fec_bd *)
> + bcom_prepare_next_buffer(priv->rx_dmatsk);
> +
> + bd->status = FEC_RX_BUFFER_SIZE;
> + bd->skb_pa = dma_map_single(&dev->dev, rskb->data,
> + FEC_RX_BUFFER_SIZE, DMA_FROM_DEVICE);
> +
> + bcom_submit_next_buffer(priv->rx_dmatsk, rskb);
> +
> + dev->stats.rx_dropped++;
> +
> + continue;
> + }
> +
> + /* skbs are allocated on open, so now we allocate a new one,
> + * and remove the old (with the packet) */
> + skb = dev_alloc_skb(FEC_RX_BUFFER_SIZE);
> + if (skb) {
> + /* Process the received skb */
> + int length = status & BCOM_FEC_RX_BD_LEN_MASK;
skb->dev = dev;
> +
> + skb_put(rskb, length - 4); /* length without CRC32 */
> +
> + rskb->dev = dev;
Above line is no longer needed since we set rskb->dev on skb allocation.
> + rskb->protocol = eth_type_trans(rskb, dev);
> +
> + netif_rx(rskb);
> + dev->last_rx = jiffies;
> + } else {
> + /* Can't get a new one : reuse the same & drop pkt */
> + dev_notice(&dev->dev, "Memory squeeze, dropping packet.\n");
> + dev->stats.rx_dropped++;
> +
> + skb = rskb;
> + }
> +
> + bd = (struct bcom_fec_bd *)
> + bcom_prepare_next_buffer(priv->rx_dmatsk);
> +
> + bd->status = FEC_RX_BUFFER_SIZE;
> + bd->skb_pa = dma_map_single(&dev->dev, rskb->data,
> + FEC_RX_BUFFER_SIZE, DMA_FROM_DEVICE);
> +
> + bcom_submit_next_buffer(priv->rx_dmatsk, skb);
> + }
> +
> + return IRQ_HANDLED;
> +}
-Dale Farnsworth
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