Re: CTS timeout issue with AR9285

[Felix Fietkau <nbd@openwrt.org>]

On 2012-02-02 5:25 AM, Seth Forshee wrote:
> I recently updated a machine with AR9285 wireless from kernel version
> 3.0 to 3.2 and saw that wireless had become slow and unreliable. It
> seems that the problem is extremely frequent CTS timeouts, which began
> happening with commit adb5066 (ath9k_hw: do not apply the 2.4 ghz ack
> timeout workaround to cts). Restoring the CTS timeout to the value prior
> to this commit on top of 3.2 gets performance back to what it was with
> 3.0.
> 
> I don't have any other ath9k cards lying around, but various other cards
> are working fine with this router. Any ideas what's wrong here?
Please try this patch:

--- a/drivers/net/wireless/ath/ath9k/hw.c
+++ b/drivers/net/wireless/ath/ath9k/hw.c
@@ -1061,13 +1061,16 @@ void ath9k_hw_init_global_settings(struc
 
 	/*
 	 * Workaround for early ACK timeouts, add an offset to match the
-	 * initval's 64us ack timeout value.
+	 * initval's 64us ack timeout value. Use 48us for the CTS timeout.
 	 * This was initially only meant to work around an issue with delayed
 	 * BA frames in some implementations, but it has been found to fix ACK
 	 * timeout issues in other cases as well.
 	 */
-	if (conf->channel && conf->channel->band == IEEE80211_BAND_2GHZ)
+	if (conf->channel && conf->channel->band == IEEE80211_BAND_2GHZ) {
 		acktimeout += 64 - sifstime - ah->slottime;
+		ctstimeout += 48 - sifstime - ah->slottime;
+	}
+
 
 	ath9k_hw_set_sifs_time(ah, sifstime);
 	ath9k_hw_setslottime(ah, slottime);