Subject: Re: [PATCH v4] FEC - fast ethernet controller for mpc52xx

From: Domen Puncer <[email-masked]>
Date: Thu, 25 Oct 2007 21:41:14 +0200

On 25/10/07 11:57 -0700, Dale Farnsworth wrote:
> 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);

It looks to me like dma_unmap_single takes the mapped address
(what dma_map_single returned), and not the address we're mapping
(skb->data).

	Domen