| Message ID | 20100120204559.177544514@vyatta.com |
|---|---|
| State | Rejected, archived |
| Delegated to: | David Miller |
| Headers | show |
On Wed, Jan 20, 2010 at 12:45:05PM -0800, Stephen Hemminger wrote: > The DMA api requires that the full mapping be sync'd when > copying frame. First found by Jarek on sky2. Are you referring to the example code in Documentation/PCI/PCI-DMA-mapping.txt? I don't see any "Use the full mapping" statement otherwise. Is there a DMA HW implementation that requires the syncing full buffer? I think it would be interesting to point that out in the commit comments since other NIC drivers are likely to also have this issue as well. I have no objection to this patch. Just want to be clear why it's being pushed. Please added Acked-by: Grant Grundler <grundler@parisc-linux.org> thanks, grant > > Signed-off-by: Stephen Hemminger <shemminger@vyatta.com> > > --- a/drivers/net/tulip/de2104x.c 2010-01-20 11:41:20.878138314 -0800 > +++ b/drivers/net/tulip/de2104x.c 2010-01-20 11:41:59.858847380 -0800 > @@ -456,11 +456,13 @@ static void de_rx (struct de_private *de > buflen, PCI_DMA_FROMDEVICE); > de->rx_skb[rx_tail].skb = copy_skb; > } else { > - pci_dma_sync_single_for_cpu(de->pdev, mapping, len, PCI_DMA_FROMDEVICE); > + pci_dma_sync_single_for_cpu(de->pdev, mapping, > + buflen, PCI_DMA_FROMDEVICE); > skb_reserve(copy_skb, RX_OFFSET); > skb_copy_from_linear_data(skb, skb_put(copy_skb, len), > len); > - pci_dma_sync_single_for_device(de->pdev, mapping, len, PCI_DMA_FROMDEVICE); > + pci_dma_sync_single_for_device(de->pdev, mapping, > + buflen, PCI_DMA_FROMDEVICE); > > /* We'll reuse the original ring buffer. */ > skb = copy_skb; > > -- -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Thu, 21 Jan 2010 18:02:44 -0700 Grant Grundler <grundler@parisc-linux.org> wrote: > On Wed, Jan 20, 2010 at 12:45:05PM -0800, Stephen Hemminger wrote: > > The DMA api requires that the full mapping be sync'd when > > copying frame. First found by Jarek on sky2. > > Are you referring to the example code in Documentation/PCI/PCI-DMA-mapping.txt? > > I don't see any "Use the full mapping" statement otherwise. > > Is there a DMA HW implementation that requires the syncing full buffer? > > I think it would be interesting to point that out in the commit comments > since other NIC drivers are likely to also have this issue as well. > > I have no objection to this patch. Just want to be clear why > it's being pushed. > > Please added Acked-by: Grant Grundler <grundler@parisc-linux.org> The documentation was in DMA-API.txt and it was wrong. The DMA debug library was enforcing a bogus restriction. Dave correctly dropped the patch. -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
--- a/drivers/net/tulip/de2104x.c 2010-01-20 11:41:20.878138314 -0800 +++ b/drivers/net/tulip/de2104x.c 2010-01-20 11:41:59.858847380 -0800 @@ -456,11 +456,13 @@ static void de_rx (struct de_private *de buflen, PCI_DMA_FROMDEVICE); de->rx_skb[rx_tail].skb = copy_skb; } else { - pci_dma_sync_single_for_cpu(de->pdev, mapping, len, PCI_DMA_FROMDEVICE); + pci_dma_sync_single_for_cpu(de->pdev, mapping, + buflen, PCI_DMA_FROMDEVICE); skb_reserve(copy_skb, RX_OFFSET); skb_copy_from_linear_data(skb, skb_put(copy_skb, len), len); - pci_dma_sync_single_for_device(de->pdev, mapping, len, PCI_DMA_FROMDEVICE); + pci_dma_sync_single_for_device(de->pdev, mapping, + buflen, PCI_DMA_FROMDEVICE); /* We'll reuse the original ring buffer. */ skb = copy_skb;
The DMA api requires that the full mapping be sync'd when copying frame. First found by Jarek on sky2. Signed-off-by: Stephen Hemminger <shemminger@vyatta.com>