[kernel/f19] Fix rt2800usb polling timeouts and throughput issues (rhbz 984696)

[Josh Boyer]

commit f3dc8d3b717c968e909e4b318809d51fe468d546
Author: Josh Boyer <jwboyer at fedoraproject.org>
Date:   Thu Oct 17 08:12:25 2013 -0400

    Fix rt2800usb polling timeouts and throughput issues (rhbz 984696)

 kernel.spec                                 |    9 +++++
 rt2800usb-slow-down-TX-status-polling.patch |   53 +++++++++++++++++++++++++++
 2 files changed, 62 insertions(+), 0 deletions(-)
---
diff --git a/kernel.spec b/kernel.spec
index 57b9ed9..413ce88 100644
--- a/kernel.spec
+++ b/kernel.spec
@@ -770,6 +770,9 @@ Patch25130: fix-radeon-sound.patch
 #rhbz 1011714
 Patch25131: btrfs-relocate-csums-properly-with-prealloc-ext.patch
 
+#rhbz 984696
+Patch25132: rt2800usb-slow-down-TX-status-polling.patch
+
 # END OF PATCH DEFINITIONS
 
 %endif
@@ -1488,6 +1491,9 @@ ApplyPatch fix-radeon-sound.patch
 #rhbz 1011714
 ApplyPatch btrfs-relocate-csums-properly-with-prealloc-ext.patch
 
+#rhbz 984696
+ApplyPatch rt2800usb-slow-down-TX-status-polling.patch
+
 # END OF PATCH APPLICATIONS
 
 %endif
@@ -2300,6 +2306,9 @@ fi
 # and build.
 
 %changelog
+* Thu Oct 17 2013 Josh Boyer <jwboyer at fedoraproject.org>
+- Fix rt2800usb polling timeouts and throughput issues (rhbz 984696)
+
 * Wed Oct 16 2013 Josh Boyer <jwboyer at fedoraproject.org> 
 - Fix btrfs balance/scrub issue (rhbz 1011714)
 
diff --git a/rt2800usb-slow-down-TX-status-polling.patch b/rt2800usb-slow-down-TX-status-polling.patch
new file mode 100644
index 0000000..a76f9b8
--- /dev/null
+++ b/rt2800usb-slow-down-TX-status-polling.patch
@@ -0,0 +1,53 @@
+Polling TX statuses too frequently has two negative effects. First is
+randomly peek CPU usage, causing overall system functioning delays.
+Second bad effect is that device is not able to fill TX statuses in
+H/W register on some workloads and we get lot of timeouts like below:
+
+ieee80211 phy4: rt2800usb_entry_txstatus_timeout: Warning - TX status timeout for entry 7 in queue 2
+ieee80211 phy4: rt2800usb_entry_txstatus_timeout: Warning - TX status timeout for entry 7 in queue 2
+ieee80211 phy4: rt2800usb_txdone: Warning - Got TX status for an empty queue 2, dropping
+
+This not only cause flood of messages in dmesg, but also bad throughput,
+since rate scaling algorithm can not work optimally.
+
+In the future, we should probably make polling interval be adjusted
+automatically, but for now just increase values, this make mentioned
+problems gone.
+
+Resolve:
+https://bugzilla.kernel.org/show_bug.cgi?id=62781
+
+Cc: stable at vger.kernel.org
+Signed-off-by: Stanislaw Gruszka <sgruszka at redhat.com>
+---
+ drivers/net/wireless/rt2x00/rt2800usb.c | 8 ++++----
+ 1 file changed, 4 insertions(+), 4 deletions(-)
+
+diff --git a/drivers/net/wireless/rt2x00/rt2800usb.c b/drivers/net/wireless/rt2x00/rt2800usb.c
+index 96677ce5..e095e61 100644
+--- a/drivers/net/wireless/rt2x00/rt2800usb.c
++++ b/drivers/net/wireless/rt2x00/rt2800usb.c
+@@ -176,8 +176,8 @@ static bool rt2800usb_tx_sta_fifo_read_completed(struct rt2x00_dev *rt2x00dev,
+ 		queue_work(rt2x00dev->workqueue, &rt2x00dev->txdone_work);
+ 
+ 	if (rt2800usb_txstatus_pending(rt2x00dev)) {
+-		/* Read register after 250 us */
+-		hrtimer_start(&rt2x00dev->txstatus_timer, ktime_set(0, 250000),
++		/* Read register after 1 ms */
++		hrtimer_start(&rt2x00dev->txstatus_timer, ktime_set(0, 1000000),
+ 			      HRTIMER_MODE_REL);
+ 		return false;
+ 	}
+@@ -202,8 +202,8 @@ static void rt2800usb_async_read_tx_status(struct rt2x00_dev *rt2x00dev)
+ 	if (test_and_set_bit(TX_STATUS_READING, &rt2x00dev->flags))
+ 		return;
+ 
+-	/* Read TX_STA_FIFO register after 500 us */
+-	hrtimer_start(&rt2x00dev->txstatus_timer, ktime_set(0, 500000),
++	/* Read TX_STA_FIFO register after 2 ms */
++	hrtimer_start(&rt2x00dev->txstatus_timer, ktime_set(0, 2000000),
+ 		      HRTIMER_MODE_REL);
+ }
+ 
+-- 
+1.8.3.1