From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752873AbaBLI3j (ORCPT ); Wed, 12 Feb 2014 03:29:39 -0500 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:50194 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752064AbaBLIOC (ORCPT ); Wed, 12 Feb 2014 03:14:02 -0500 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, "Peter Korsgaard" , "Joseph Chang" , "David S. Miller" Date: Wed, 12 Feb 2014 08:10:12 +0000 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.2 55/79] dm9601: work around tx fifo sync issue on dm962x In-Reply-To: X-SA-Exim-Connect-IP: 91.84.160.45 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.2.55-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Peter Korsgaard 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 Signed-off-by: Peter Korsgaard Signed-off-by: David S. Miller Signed-off-by: Ben Hutchings --- drivers/net/usb/dm9601.c | 27 +++++++++++++++++++-------- 1 file changed, 19 insertions(+), 8 deletions(-) --- a/drivers/net/usb/dm9601.c +++ b/drivers/net/usb/dm9601.c @@ -536,7 +536,7 @@ static int dm9601_rx_fixup(struct usbnet 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 @@ -544,12 +544,23 @@ static struct sk_buff *dm9601_tx_fixup(s 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) @@ -558,10 +569,10 @@ static struct sk_buff *dm9601_tx_fixup(s __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;