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Commit 4263c86d authored by Peter Korsgaard's avatar Peter Korsgaard Committed by David S. Miller
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dm9601: work around tx fifo sync issue on dm962x 



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: default avatarJoseph Chang <joseph_chang@davicom.com.tw>
Signed-off-by: default avatarPeter Korsgaard <peter@korsgaard.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent cabd0e3a

drivers/net/usb/dm9601.c

+19 −8
Original line number Diff line number Diff line
@@ -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;