From: Rajkumar Manoharan <rmanohar@qca.qualcomm.com>
Date: Thu, 15 Mar 2012 00:38:04 +0000 (+0530)
Subject: ath9k: fix max noise floor threshold
X-Git-Url: http://git.alex.org.uk

ath9k: fix max noise floor threshold

BugLink: http://bugs.launchpad.net/bugs/987337

commit 2ee0a07028d2cde6e131b73f029dae2b93c50f3a upstream.

Currently the maximum noise floor limit is set as too high (-60dB). The
assumption of having a higher threshold limit is that it would help
de-sensitize the receiver (reduce phy errors) from continuous
interference. But when we have a bursty interference where there are
collisions and then free air time and if the receiver is desensitized too
much, it will miss the normal packets too. Lets make use of chips
specific min, nom and max limits always. This patch helps to improve the
connection stability in congested networks.

Cc: Paul Stewart <pstew@google.com>
Tested-by: Gary Morain <gmorain@google.com>
Signed-off-by: Madhan Jaganathan <madhanj@qca.qualcomm.com>
Signed-off-by: Rajkumar Manoharan <rmanohar@qca.qualcomm.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
[bwh: Backported to 3.0/3.2: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Tim Gardner <tim.gardner@canonical.com>
---

diff --git a/drivers/net/wireless/ath/ath9k/calib.c b/drivers/net/wireless/ath/ath9k/calib.c
index 8ddef3e..d771de5 100644
--- a/drivers/net/wireless/ath/ath9k/calib.c
+++ b/drivers/net/wireless/ath/ath9k/calib.c
@@ -20,7 +20,6 @@
 
 /* Common calibration code */
 
-#define ATH9K_NF_TOO_HIGH	-60
 
 static int16_t ath9k_hw_get_nf_hist_mid(int16_t *nfCalBuffer)
 {
@@ -348,10 +347,10 @@ static void ath9k_hw_nf_sanitize(struct ath_hw *ah, s16 *nf)
 			"NF calibrated [%s] [chain %d] is %d\n",
 			(i >= 3 ? "ext" : "ctl"), i % 3, nf[i]);
 
-		if (nf[i] > ATH9K_NF_TOO_HIGH) {
+		if (nf[i] > limit->max) {
 			ath_dbg(common, ATH_DBG_CALIBRATE,
 				"NF[%d] (%d) > MAX (%d), correcting to MAX\n",
-				i, nf[i], ATH9K_NF_TOO_HIGH);
+				i, nf[i], limit->max);
 			nf[i] = limit->max;
 		} else if (nf[i] < limit->min) {
 			ath_dbg(common, ATH_DBG_CALIBRATE,