--- /dev/null
+From b251412db99ccd4495ce372fec7daee27bf06923 Mon Sep 17 00:00:00 2001
+From: "Iestyn C. Elfick" <isedev@gmail.com>
+Date: Wed, 20 Mar 2013 14:02:31 -0500
+Subject: b43: A fix for DMA transmission sequence errors
+
+From: "Iestyn C. Elfick" <isedev@gmail.com>
+
+commit b251412db99ccd4495ce372fec7daee27bf06923 upstream.
+
+Intermittently, b43 will report "Out of order TX status report on DMA ring".
+When this happens, the driver must be reset before communication can resume.
+The cause of the problem is believed to be an error in the closed-source
+firmware; however, all versions of the firmware are affected.
+
+This change uses the observation that the expected status is always 2 less
+than the observed value, and supplies a fake status report to skip one
+header/data pair.
+
+Not all devices suffer from this problem, but it can occur several times
+per second under heavy load. As each occurence kills the unmodified driver,
+this patch makes if possible for the affected devices to function. The patch
+logs only the first instance of the reset operation to prevent spamming
+the logs.
+
+Tested-by: Chris Vine <chris@cvine.freeserve.co.uk>
+Signed-off-by: Larry Finger <Larry.Finger@lwfinger.net>
+Signed-off-by: John W. Linville <linville@tuxdriver.com>
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+
+---
+ drivers/net/wireless/b43/dma.c | 65 +++++++++++++++++++++++++++++++++--------
+ 1 file changed, 53 insertions(+), 12 deletions(-)
+
+--- a/drivers/net/wireless/b43/dma.c
++++ b/drivers/net/wireless/b43/dma.c
+@@ -1390,8 +1390,12 @@ void b43_dma_handle_txstatus(struct b43_
+ struct b43_dmaring *ring;
+ struct b43_dmadesc_generic *desc;
+ struct b43_dmadesc_meta *meta;
++ static const struct b43_txstatus fake; /* filled with 0 */
++ const struct b43_txstatus *txstat;
+ int slot, firstused;
+ bool frame_succeed;
++ int skip;
++ static u8 err_out1, err_out2;
+
+ ring = parse_cookie(dev, status->cookie, &slot);
+ if (unlikely(!ring))
+@@ -1404,13 +1408,36 @@ void b43_dma_handle_txstatus(struct b43_
+ firstused = ring->current_slot - ring->used_slots + 1;
+ if (firstused < 0)
+ firstused = ring->nr_slots + firstused;
++
++ skip = 0;
+ if (unlikely(slot != firstused)) {
+ /* This possibly is a firmware bug and will result in
+- * malfunction, memory leaks and/or stall of DMA functionality. */
+- b43dbg(dev->wl, "Out of order TX status report on DMA ring %d. "
+- "Expected %d, but got %d\n",
+- ring->index, firstused, slot);
+- return;
++ * malfunction, memory leaks and/or stall of DMA functionality.
++ */
++ if (slot == next_slot(ring, next_slot(ring, firstused))) {
++ /* If a single header/data pair was missed, skip over
++ * the first two slots in an attempt to recover.
++ */
++ slot = firstused;
++ skip = 2;
++ if (!err_out1) {
++ /* Report the error once. */
++ b43dbg(dev->wl,
++ "Skip on DMA ring %d slot %d.\n",
++ ring->index, slot);
++ err_out1 = 1;
++ }
++ } else {
++ /* More than a single header/data pair were missed.
++ * Report this error once.
++ */
++ if (!err_out2)
++ b43dbg(dev->wl,
++ "Out of order TX status report on DMA ring %d. Expected %d, but got %d\n",
++ ring->index, firstused, slot);
++ err_out2 = 1;
++ return;
++ }
+ }
+
+ ops = ring->ops;
+@@ -1424,11 +1451,13 @@ void b43_dma_handle_txstatus(struct b43_
+ slot, firstused, ring->index);
+ break;
+ }
++
+ if (meta->skb) {
+ struct b43_private_tx_info *priv_info =
+- b43_get_priv_tx_info(IEEE80211_SKB_CB(meta->skb));
++ b43_get_priv_tx_info(IEEE80211_SKB_CB(meta->skb));
+
+- unmap_descbuffer(ring, meta->dmaaddr, meta->skb->len, 1);
++ unmap_descbuffer(ring, meta->dmaaddr,
++ meta->skb->len, 1);
+ kfree(priv_info->bouncebuffer);
+ priv_info->bouncebuffer = NULL;
+ } else {
+@@ -1440,8 +1469,9 @@ void b43_dma_handle_txstatus(struct b43_
+ struct ieee80211_tx_info *info;
+
+ if (unlikely(!meta->skb)) {
+- /* This is a scatter-gather fragment of a frame, so
+- * the skb pointer must not be NULL. */
++ /* This is a scatter-gather fragment of a frame,
++ * so the skb pointer must not be NULL.
++ */
+ b43dbg(dev->wl, "TX status unexpected NULL skb "
+ "at slot %d (first=%d) on ring %d\n",
+ slot, firstused, ring->index);
+@@ -1452,9 +1482,18 @@ void b43_dma_handle_txstatus(struct b43_
+
+ /*
+ * Call back to inform the ieee80211 subsystem about
+- * the status of the transmission.
++ * the status of the transmission. When skipping over
++ * a missed TX status report, use a status structure
++ * filled with zeros to indicate that the frame was not
++ * sent (frame_count 0) and not acknowledged
+ */
+- frame_succeed = b43_fill_txstatus_report(dev, info, status);
++ if (unlikely(skip))
++ txstat = &fake;
++ else
++ txstat = status;
++
++ frame_succeed = b43_fill_txstatus_report(dev, info,
++ txstat);
+ #ifdef CONFIG_B43_DEBUG
+ if (frame_succeed)
+ ring->nr_succeed_tx_packets++;
+@@ -1482,12 +1521,14 @@ void b43_dma_handle_txstatus(struct b43_
+ /* Everything unmapped and free'd. So it's not used anymore. */
+ ring->used_slots--;
+
+- if (meta->is_last_fragment) {
++ if (meta->is_last_fragment && !skip) {
+ /* This is the last scatter-gather
+ * fragment of the frame. We are done. */
+ break;
+ }
+ slot = next_slot(ring, slot);
++ if (skip > 0)
++ --skip;
+ }
+ if (ring->stopped) {
+ B43_WARN_ON(free_slots(ring) < TX_SLOTS_PER_FRAME);
projects / thirdparty / kernel / stable-queue.git / commitdiff
