Re: [Bug #14057] Strange network timeouts w/ e100

Rafael J. Wysocki
2009-08-26T22:23:51Z

On Thursday 27 August 2009, David Miller wrote:
> From: "Rafael J. Wysocki" <rjw-KKrjLPT3xs0@public.gmane.org>
> Date: Wed, 26 Aug 2009 23:12:03 +0200
>
> >> Krzysztof has a patch which has corrected this issue for me. Thanks,
> >
> > Thanks for the update.
> >
> > Do you have a pointer to the patch, please?
>
> commit 6ff9c2e7fa8ca63a575792534b63c5092099c286
> Author: Krzysztof Hałasa <khc-9GfyWEdoJtJmR6Xm/wNWPw@public.gmane.org>
> Date: Sun Aug 23 19:02:13 2009 -0700
>
> E100: fix interaction with swiotlb on X86.
>
> E100 places it's RX packet descriptors inside skb->data and uses them
> with bidirectional streaming DMA mapping. Data in descriptors is
> accessed simultaneously by the chip (writing status and size when
> a packet is received) and CPU (reading to check if the packet was
> received). This isn't a valid usage of PCI DMA API, which requires use
> of the coherent (consistent) memory for such purpose. Unfortunately e100
> chips working in "simplified" RX mode have to store received data
> directly after the descriptor. Fixing the driver to conform to the API
> would require using unsupported "flexible" RX mode or receiving data
> into a coherent memory and using CPU to copy it to network buffers.
>
> This patch, while not yet making the driver conform to the PCI DMA API,
> allows it to work correctly on X86 with swiotlb (while not breaking
> other architectures).
>
> Signed-off-by: Krzysztof Hałasa <khc-9GfyWEdoJtJmR6Xm/wNWPw@public.gmane.org>
> Signed-off-by: David S. Miller <davem-fT/PcQaiUtIeIZ0/mPfg9Q@public.gmane.org>
>
> diff --git a/drivers/net/e100.c b/drivers/net/e100.c
> index 41b648a..3a6735d 100644
> --- a/drivers/net/e100.c
> +++ b/drivers/net/e100.c
> @@ -1899,7 +1899,7 @@ static int e100_rx_indicate(struct nic *nic, struct rx *rx,
> nic->ru_running = RU_SUSPENDED;
> pci_dma_sync_single_for_device(nic->pdev, rx->dma_addr,
> sizeof(struct rfd),
> - PCI_DMA_BIDIRECTIONAL);
> + PCI_DMA_FROMDEVICE);
> return -ENODATA;
> }

Thanks a lot, bug closed.

Rafael