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ath9k_hw: Fix signal strength / channel noise reporting 

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@openwrt.org>
Cc: stable@vger.kernel.org
Signed-off-by: John W. Linville <linville@tuxdriver.com>
This commit is contained in:
Felix Fietkau 2012-12-10 14:03:17 +01:00 committed by John W. Linville
parent cbbc0138ef
commit b7c0c23889
2 changed files with 4 additions and 0 deletions
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1
drivers/net/wireless/ath/ath9k/calib.c
View File

@ -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;

3
drivers/net/wireless/ath/ath9k/calib.h
View File

@ -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