答复: [PATCH] fs_enet: fix freescale FCC ethernet dp buffer alignment

[杨勇]

Hello,
Motioned to the memory aligned, now there is such requirement:
When the driver send an packet to hardware, the skb's address passed by
stack do a dma map into hardware, the skb's dma address must be 64-byte
aligned.
My method:
 Allocate a new skb which is 64-byte aligned, then copy the passed skb to
new one
After test, the driver can work and overcome this issue.
But I eager to get a perfect solution about that, could you offer me a nice
one? Thanks so much~~

Code：
static struct sk_buff * skb_align_copy(const struct sk_buff *skb, gfp_t
gfp_mask)
{
    if((skb->len + LEN_INFO_BYTES) > 2000 ){
        atomic_inc(&proc_stat[PROC_STAT_JUMBO_CNT]);
        return NULL;
    }    

    struct sk_buff *n;
    n = alloc_skb(2048, gfp_mask);  //0 headroom
    if(!n)
        return NULL;

    atomic_inc(&proc_stat[PROC_STAT_SKB_ALLOC]);
    skb_put(n, skb->len + LEN_INFO_BYTES);

    if((skb->data - LEN_INFO_BYTES) == NULL){
        c_err("skb->data - LEN_INFO_BYTES is NULL!\n");
        return NULL;
    }    
    memcpy(n->data, skb->data - LEN_INFO_BYTES, skb->len + LEN_INFO_BYTES);
    return n;
}
static int ne_pcie_tx_map(struct ne_pcie_ring* tx_ring, struct sk_buff* skb)
{
    struct ne_pcie_buff* buff;
    struct sk_buff* align_skb;
    int i = tx_ring->next_to_use;
    int len = skb->len;
    int count = 0;

    align_skb = skb_align_copy(skb, GFP_ATOMIC);
    if(!align_skb){
        goto dma_map_error;
    }

    buff = &tx_ring->buffer[i];
    buff->length = len+LEN_INFO_BYTES;
    buff->dma = pci_map_single(tx_ring->pci_dev, align_skb->data,
            len+LEN_INFO_BYTES, PCI_DMA_TODEVICE);
    if (pci_dma_mapping_error(tx_ring->pci_dev, buff->dma)) {
        goto dma_map_error;
    }



-----邮件原件-----
发件人: netdev-owner at vger.kernel.org [mailto:netdev-owner at vger.kernel.org]
代表 Holger Brunck
发送时间: 2011年6月17日 16:31
收件人: linuxppc-dev at lists.ozlabs.org
抄送: Clive Stubbings; Holger Brunck; Pantelis Antoniou; Vitaly Bordug;
netdev at vger.kernel.org
主题: [PATCH] fs_enet: fix freescale FCC ethernet dp buffer alignment

From: Clive Stubbings <clive.stubbings at xentech.co.uk>

The RIPTR and TIPTR  (receive/transmit internal temporary data pointer),
used by microcode as a temporary buffer for data, must be 32-byte aligned
according to the RM for MPC8247.

Tested on mgcoge.

Signed-off-by: Clive Stubbings <clive.stubbings at xentech.co.uk>
Signed-off-by: Holger Brunck <holger.brunck at keymile.com>
cc: Pantelis Antoniou <pantelis.antoniou at gmail.com>
cc: Vitaly Bordug <vbordug at ru.mvista.com>
cc: netdev at vger.kernel.org
---
This fixes a kernel crash on mgcoge when using SPI on CPM2 and
ethernet over FCC. Now fixed because the fcc driver now allocates
the space he really needs.

 drivers/net/fs_enet/mac-fcc.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/drivers/net/fs_enet/mac-fcc.c b/drivers/net/fs_enet/mac-fcc.c
index 7a84e45..7583a95 100644
--- a/drivers/net/fs_enet/mac-fcc.c
+++ b/drivers/net/fs_enet/mac-fcc.c
@@ -105,7 +105,7 @@ static int do_pd_setup(struct fs_enet_private *fep)
 		goto out_ep;
 
 	fep->fcc.mem = (void __iomem *)cpm2_immr;
-	fpi->dpram_offset = cpm_dpalloc(128, 8);
+	fpi->dpram_offset = cpm_dpalloc(128, 32);
 	if (IS_ERR_VALUE(fpi->dpram_offset)) {
 		ret = fpi->dpram_offset;
 		goto out_fcccp;
-- 
1.7.1

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