[ 3.5.y.z extended stable ] Patch "ath9k_hw: Fix signal strength / channel noise reporting" has been added to staging queue

[Herton Ronaldo Krzesinski]

This is a note to let you know that I have just added a patch titled

    ath9k_hw: Fix signal strength / channel noise reporting

to the linux-3.5.y-queue branch of the 3.5.y.z extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.5.y-queue

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.5.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Herton

------

>From 3f9493fc489c2c599edb2834157c51b36c7ba30f Mon Sep 17 00:00:00 2001
From: Felix Fietkau <nbd at openwrt.org>
Date: Mon, 10 Dec 2012 14:03:17 +0100
Subject: [PATCH] ath9k_hw: Fix signal strength / channel noise reporting

commit b7c0c238898d200e80487516e2b67aba2a522cc0 upstream.

While AR_PHY_CCA_NOM_VAL_* does contain the expected internal noise floor
for a chip measured in clean air, it refers to the lowest expected reading.

Depending on the frequency, this measurement can vary by about 6db, thus
causing a higher reported channel noise and signal strength.

Factor in the 6db offset when converting internal noisefloor to channel noise.

This patch makes the reported values more accurate for all chips without
affecting NF calibration behavior.

Signed-off-by: Felix Fietkau <nbd at openwrt.org>
Signed-off-by: John W. Linville <linville at tuxdriver.com>
Signed-off-by: Herton Ronaldo Krzesinski <herton.krzesinski at canonical.com>
---
 drivers/net/wireless/ath/ath9k/calib.c |    1 +
 drivers/net/wireless/ath/ath9k/calib.h |    3 +++
 2 files changed, 4 insertions(+)

diff --git a/drivers/net/wireless/ath/ath9k/calib.c b/drivers/net/wireless/ath/ath9k/calib.c
index e5cceb0..bbd249d 100644
--- a/drivers/net/wireless/ath/ath9k/calib.c
+++ b/drivers/net/wireless/ath/ath9k/calib.c
@@ -69,6 +69,7 @@ s16 ath9k_hw_getchan_noise(struct ath_hw *ah, struct ath9k_channel *chan)

 	if (chan && chan->noisefloor) {
 		s8 delta = chan->noisefloor -
+			   ATH9K_NF_CAL_NOISE_THRESH -
 			   ath9k_hw_get_default_nf(ah, chan);
 		if (delta > 0)
 			noise += delta;
diff --git a/drivers/net/wireless/ath/ath9k/calib.h b/drivers/net/wireless/ath/ath9k/calib.h
index 3b33996d..1f2e01a 100644
--- a/drivers/net/wireless/ath/ath9k/calib.h
+++ b/drivers/net/wireless/ath/ath9k/calib.h
@@ -21,6 +21,9 @@

 #define AR_PHY_CCA_FILTERWINDOW_LENGTH          5

+/* Internal noise floor can vary by about 6db depending on the frequency */
+#define ATH9K_NF_CAL_NOISE_THRESH		6
+
 #define NUM_NF_READINGS       6
 #define ATH9K_NF_CAL_HIST_MAX 5

--
1.7.9.5