[PATCH 1/3] ath9k: fix signal strength of received packets

[PATCH 1/3] ath9k: fix signal strength of received packets

[Felix Fietkau]

The reported RSSI values are relative to the calibrated noise floor, not
relative to a hardcoded value of -95.

Signed-off-by: Felix Fietkau <nbd@openwrt.org>
---
 drivers/net/wireless/ath/ath9k/recv.c |   11 ++++++++++-
 1 files changed, 10 insertions(+), 1 deletions(-)

diff --git a/drivers/net/wireless/ath/ath9k/recv.c b/drivers/net/wireless/ath/ath9k/recv.c
index a9c3f46..87d96c5 100644
--- a/drivers/net/wireless/ath/ath9k/recv.c
+++ b/drivers/net/wireless/ath/ath9k/recv.c
@@ -959,6 +959,9 @@ static int ath9k_rx_skb_preprocess(struct ath_common *common,
 				   struct ieee80211_rx_status *rx_status,
 				   bool *decrypt_error)
 {
+	struct ath_hw *ah = common->ah;
+	int noise;
+
 	memset(rx_status, 0, sizeof(struct ieee80211_rx_status));
 
 	/*
@@ -979,7 +982,13 @@ static int ath9k_rx_skb_preprocess(struct ath_common *common,
 
 	rx_status->band = hw->conf.channel->band;
 	rx_status->freq = hw->conf.channel->center_freq;
-	rx_status->signal = ATH_DEFAULT_NOISE_FLOOR + rx_stats->rs_rssi;
+
+	if (ah->curchan)
+		noise = ah->curchan->noisefloor;
+	else
+		noise = ATH_DEFAULT_NOISE_FLOOR;
+
+	rx_status->signal = noise + rx_stats->rs_rssi;
 	rx_status->antenna = rx_stats->rs_antenna;
 	rx_status->flag |= RX_FLAG_MACTIME_MPDU;
 
-- 
1.7.3.2

[PATCH 2/3] ath9k: fix beacon slot processing in ad-hoc mode

[Felix Fietkau]

The recent cleanups in the beacon code fixed SWBA backoff calculation,
however it did not remove a line of code that worked around the issues
from the earlier version of the code.
After the cleanup, the initial TSF based slot calculation now always
returns 0 instead of ATH_BCBUF-1, so the previous hack that reversed the
slot order needs to be removed, as ad-hoc mode does not use staggered
beacons.

Signed-off-by: Felix Fietkau <nbd@openwrt.org>
---
 drivers/net/wireless/ath/ath9k/beacon.c |    8 --------
 1 files changed, 0 insertions(+), 8 deletions(-)

diff --git a/drivers/net/wireless/ath/ath9k/beacon.c b/drivers/net/wireless/ath/ath9k/beacon.c
index 74f33bc..24861b2 100644
--- a/drivers/net/wireless/ath/ath9k/beacon.c
+++ b/drivers/net/wireless/ath/ath9k/beacon.c
@@ -392,14 +392,6 @@ void ath_beacon_tasklet(unsigned long data)
 	tsf += TU_TO_USEC(ah->config.sw_beacon_response_time);
 	tsftu = TSF_TO_TU((tsf * ATH_BCBUF) >>32, tsf * ATH_BCBUF);
 	slot = (tsftu % (intval * ATH_BCBUF)) / intval;
-	/*
-	 * Reverse the slot order to get slot 0 on the TBTT offset that does
-	 * not require TSF adjustment and other slots adding
-	 * slot/ATH_BCBUF * beacon_int to timestamp. For example, with
-	 * ATH_BCBUF = 4, we process beacon slots as follows: 3 2 1 0 3 2 1 ..
-	 * and slot 0 is at correct offset to TBTT.
-	 */
-	slot = ATH_BCBUF - slot - 1;
 	vif = sc->beacon.bslot[slot];
 
 	ath_dbg(common, ATH_DBG_BEACON,
-- 
1.7.3.2

[PATCH 3/3] ath9k: use the hw opmode to select the beacon timer mode

[Felix Fietkau]

Since the beacon timers are global, the individual vif type should not
be used to determine the beacon timer configuration mode, use the
global opmode instead.

Signed-off-by: Felix Fietkau <nbd@openwrt.org>
---
 drivers/net/wireless/ath/ath9k/beacon.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/drivers/net/wireless/ath/ath9k/beacon.c b/drivers/net/wireless/ath/ath9k/beacon.c
index 24861b2..f688527 100644
--- a/drivers/net/wireless/ath/ath9k/beacon.c
+++ b/drivers/net/wireless/ath/ath9k/beacon.c
@@ -700,7 +700,7 @@ void ath_beacon_config(struct ath_softc *sc, struct ieee80211_vif *vif)
 	if (cur_conf->dtim_period == 0)
 		cur_conf->dtim_period = 1;
 
-	switch (iftype) {
+	switch (sc->sc_ah->opmode) {
 	case NL80211_IFTYPE_AP:
 		ath_beacon_config_ap(sc, cur_conf);
 		break;
-- 
1.7.3.2

Re: [PATCH 1/3] ath9k: fix signal strength of received packets

[Senthil Balasubramanian]

On Sat, Apr 02, 2011 at 03:39:46AM +0200, Felix Fietkau wrote:
> The reported RSSI values are relative to the calibrated noise floor, not
> relative to a hardcoded value of -95.
> 
> Signed-off-by: Felix Fietkau <nbd@openwrt.org>
> ---
>  drivers/net/wireless/ath/ath9k/recv.c |   11 ++++++++++-
>  1 files changed, 10 insertions(+), 1 deletions(-)
> 
> diff --git a/drivers/net/wireless/ath/ath9k/recv.c b/drivers/net/wireless/ath/ath9k/recv.c
> index a9c3f46..87d96c5 100644
> --- a/drivers/net/wireless/ath/ath9k/recv.c
> +++ b/drivers/net/wireless/ath/ath9k/recv.c
> @@ -959,6 +959,9 @@ static int ath9k_rx_skb_preprocess(struct ath_common *common,
>  				   struct ieee80211_rx_status *rx_status,
>  				   bool *decrypt_error)
>  {
> +	struct ath_hw *ah = common->ah;
> +	int noise;
> +
>  	memset(rx_status, 0, sizeof(struct ieee80211_rx_status));
>  
>  	/*
> @@ -979,7 +982,13 @@ static int ath9k_rx_skb_preprocess(struct ath_common *common,
>  
>  	rx_status->band = hw->conf.channel->band;
>  	rx_status->freq = hw->conf.channel->center_freq;
> -	rx_status->signal = ATH_DEFAULT_NOISE_FLOOR + rx_stats->rs_rssi;
In some cases noisefloor values were not reliable and so using
default works for most of the cases. Please refer to our earlier
commit a59b5a5e684652eec035c869ab8911a1689c8f53. Let me see if i
can get more information.
> +
> +	if (ah->curchan)
> +		noise = ah->curchan->noisefloor;
Even otherwise, noisefloor can be zero sometimes and so it can
return incorrect signal strengths.. Please refer to some samples.

BSS 00:10:18:90:3a:9e (on wlan56)
        TSF: 110532917222 usec (1d, 06:42:12)
        freq: 2462
        beacon interval: 100
        capability: ESS (0x0001)
        signal: 50.00 dBm
        last seen: 20 ms ago
        SSID: Broadcom
        Supported rates: 1.0* 2.0* 5.5* 11.0* 18.0 24.0 36.0 54.0
        DS Parameter set: channel 11
        ERP: NonERP_Present Use_Protection Barker_Preamble_Mode
        Extended supported rates: 6.0 9.0 12.0 48.0
        HT capabilities:

SS 00:03:7f:0b:a6:1b (on wlan56)
        TSF: 4376472960 usec (0d, 01:12:56)
        freq: 2462
        beacon interval: 100
        capability: ESS Privacy ShortPreamble (0x0031)
        signal: 60.00 dBm
        last seen: 8 ms ago
        SSID: STRESS-HB125

> +	else
> +		noise = ATH_DEFAULT_NOISE_FLOOR;
> +
> +	rx_status->signal = noise + rx_stats->rs_rssi;
>  	rx_status->antenna = rx_stats->rs_antenna;
>  	rx_status->flag |= RX_FLAG_MACTIME_MPDU;
>  
> -- 
> 1.7.3.2
> 
> --
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Re: [PATCH 1/3] ath9k: fix signal strength of received packets

[Felix Fietkau]

On 2011-04-05 8:07 PM, Senthil Balasubramanian wrote:
> On Sat, Apr 02, 2011 at 03:39:46AM +0200, Felix Fietkau wrote:
>>  The reported RSSI values are relative to the calibrated noise floor, not
>>  relative to a hardcoded value of -95.
>>
>>  Signed-off-by: Felix Fietkau<nbd@openwrt.org>
>>  ---
>>   drivers/net/wireless/ath/ath9k/recv.c |   11 ++++++++++-
>>   1 files changed, 10 insertions(+), 1 deletions(-)
>>
>>  diff --git a/drivers/net/wireless/ath/ath9k/recv.c b/drivers/net/wireless/ath/ath9k/recv.c
>>  index a9c3f46..87d96c5 100644
>>  --- a/drivers/net/wireless/ath/ath9k/recv.c
>>  +++ b/drivers/net/wireless/ath/ath9k/recv.c
>>  @@ -959,6 +959,9 @@ static int ath9k_rx_skb_preprocess(struct ath_common *common,
>>   				struct ieee80211_rx_status *rx_status,
>>   				bool *decrypt_error)
>>   {
>>  +	struct ath_hw *ah = common->ah;
>>  +	int noise;
>>  +
>>   	memset(rx_status, 0, sizeof(struct ieee80211_rx_status));
>>
>>   	/*
>>  @@ -979,7 +982,13 @@ static int ath9k_rx_skb_preprocess(struct ath_common *common,
>>
>>   	rx_status->band = hw->conf.channel->band;
>>   	rx_status->freq = hw->conf.channel->center_freq;
>>  -	rx_status->signal = ATH_DEFAULT_NOISE_FLOOR + rx_stats->rs_rssi;
> In some cases noisefloor values were not reliable and so using
> default works for most of the cases. Please refer to our earlier
> commit a59b5a5e684652eec035c869ab8911a1689c8f53. Let me see if i
> can get more information.
Well, if the average noise floor is at -110 (which is not uncommon with 
AR9280 chipsets) then that means the signal strength is off by at least 
15 dBm as well.

>>  +
>>  +	if (ah->curchan)
>>  +		noise = ah->curchan->noisefloor;
> Even otherwise, noisefloor can be zero sometimes and so it can
> return incorrect signal strengths.. Please refer to some samples.
OK, that's easy to fix, we only need to initialize the channel 
noisefloor when we switch to the channel. I'll make a patch to fix it 
the noisefloor values and then resend this one.

John, please drop this patch but apply the other two in the series.

- Felix