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authorPeter Korsgaard <peter@korsgaard.com>2013-12-16 11:35:35 +0100
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2014-01-09 12:24:22 -0800
commit5fd93067a1e7bc8ce6a889816d2b4c2d19a2e970 (patch)
tree2bfddfeb1ff90283ca3d869ae88cca18ce4f2312 /drivers/net
parent1552c3d8e10d1113d55237f3dd0d65c0a3501632 (diff)
downloadlinaro-lsk-5fd93067a1e7bc8ce6a889816d2b4c2d19a2e970.tar.gz
dm9601: work around tx fifo sync issue on dm962x
commit 4263c86dca5198da6bd3ad826d0b2304fbe25776 upstream. 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. 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> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/net')
-rw-r--r--drivers/net/usb/dm9601.c27
1 files changed, 19 insertions, 8 deletions
diff --git a/drivers/net/usb/dm9601.c b/drivers/net/usb/dm9601.c
index 732a926e3f5..c0bfc818c70 100644
--- a/drivers/net/usb/dm9601.c
+++ b/drivers/net/usb/dm9601.c
@@ -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;
+
+ /* 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++;
- if (skb_headroom(skb) < DM_TX_OVERHEAD) {
+ 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;