lkml.org 
[lkml]   [2012]   [Apr]   [4]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    Date
    From
    SubjectRe: [PATCH v2] marvell sky2 driver: fix so it works without unaligned accesses
    On Wed, 4 Apr 2012 10:13:32 -0400
    Chris Metcalf <cmetcalf@tilera.com> wrote:

    > The driver uses a receive_new() routine that ends up requiring unaligned
    > accesses in IP header processing. If the architecture doesn't support
    > efficient unaligned accesses, and SKY2_HW_RAM_BUFFER is set,
    > just copy all ingress packets to the bounce buffers instead.
    > Thanks to Eric Dumazet for pointing out the SKY2_HW_RAM_BUFFER issue.
    >
    > This allows the driver to be used on the Tilera TILEmpower-Gx, since
    > the tile architecture doesn't currently handle kernel unaligned accesses,
    > just userspace.
    >
    > Signed-off-by: Chris Metcalf <cmetcalf@tilera.com>
    > ---
    > drivers/net/ethernet/marvell/sky2.c | 6 +++++-
    > 1 files changed, 5 insertions(+), 1 deletions(-)

    What about the following (compile tested only)
    --- a/drivers/net/ethernet/marvell/sky2.c 2012-04-04 08:49:05.954853108 -0700
    +++ b/drivers/net/ethernet/marvell/sky2.c 2012-04-04 11:30:54.201432707 -0700
    @@ -2468,6 +2468,17 @@ static int sky2_change_mtu(struct net_de
    return err;
    }

    +static inline bool needs_copy(const struct rx_ring_info *re,
    + unsigned length)
    +{
    +#ifndef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
    + /* Some architectures need the IP header to be aligned */
    + if (!IS_ALIGNED(re->data_addr + ETH_HLEN, sizeof(u32)))
    + return 1;
    +#endif
    + return length < copybreak;
    +}
    +
    /* For small just reuse existing skb for next receive */
    static struct sk_buff *receive_copy(struct sky2_port *sky2,
    const struct rx_ring_info *re,
    @@ -2605,7 +2616,7 @@ static struct sk_buff *sky2_receive(stru
    goto error;

    okay:
    - if (length < copybreak)
    + if (needs_copy(re, length))
    skb = receive_copy(sky2, re, length);
    else
    skb = receive_new(sky2, re, length);

    \
     
     \ /
      Last update: 2012-04-04 20:45    [W:0.024 / U:0.124 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site