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dm9601: work around tx fifo sync issue on dm962x

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Certain dm962x revisions contain an bug, where if a USB bulk transfer retry
(E.G. if bulk crc mismatch) happens right after a transfer with odd or
maxpacket length, the internal tx hardware fifo gets out of sync causing
the interface to stop working.

Work around it by adding up to 3 bytes of padding to ensure this situation
cannot trigger.

This workaround also means we never pass multiple-of-maxpacket size skb's
to usbnet, so the length adjustment to handle usbnet's padding of those can
be removed.

Cc: <stable@vger.kernel.org>
Reported-by: Joseph Chang <joseph_chang@davicom.com.tw>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Peter Korsgaard 2013-12-16 11:35:35 +01:00 committed by David S. Miller
parent cabd0e3a38
commit 4263c86dca
1 changed files with 19 additions and 8 deletions
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27
drivers/net/usb/dm9601.c
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@ -473,7 +473,7 @@ static int dm9601_rx_fixup(struct usbnet *dev, struct sk_buff *skb)
static struct sk_buff *dm9601_tx_fixup(struct usbnet *dev, struct sk_buff *skb,
gfp_t flags)
{
int len;
int len, pad;
/* format:
b1: packet length low
@ -481,12 +481,23 @@ static struct sk_buff *dm9601_tx_fixup(struct usbnet *dev, struct sk_buff *skb,
b3..n: packet data
*/
len = skb->len;
len = skb->len + DM_TX_OVERHEAD;
if (skb_headroom(skb) < DM_TX_OVERHEAD) {
/* workaround for dm962x errata with tx fifo getting out of
* sync if a USB bulk transfer retry happens right after a
* packet with odd / maxpacket length by adding up to 3 bytes
* padding.
*/
while ((len & 1) || !(len % dev->maxpacket))
len++;
len -= DM_TX_OVERHEAD; /* hw header doesn't count as part of length */
pad = len - skb->len;
if (skb_headroom(skb) < DM_TX_OVERHEAD || skb_tailroom(skb) < pad) {
struct sk_buff *skb2;
skb2 = skb_copy_expand(skb, DM_TX_OVERHEAD, 0, flags);
skb2 = skb_copy_expand(skb, DM_TX_OVERHEAD, pad, flags);
dev_kfree_skb_any(skb);
skb = skb2;
if (!skb)
@ -495,10 +506,10 @@ static struct sk_buff *dm9601_tx_fixup(struct usbnet *dev, struct sk_buff *skb,
__skb_push(skb, DM_TX_OVERHEAD);
/* usbnet adds padding if length is a multiple of packet size
if so, adjust length value in header */
if ((skb->len % dev->maxpacket) == 0)
len++;
if (pad) {
memset(skb->data + skb->len, 0, pad);
__skb_put(skb, pad);
}
skb->data[0] = len;
skb->data[1] = len >> 8;