ath9k: enable ANI to help with noisy environments

This enables Adaptive Noise Immunity (ANI) on ath9k.
ANI is as algorithm designed to minimize the detrimental
effects of time-varying interferences. This should
help with throughput in noisy environments. To use
ANI we re-enable the MIB interrupt. Since ANI works
on a timer and updates the noise floor we take
advantage of this and also report a non-static noise
floor now to mac80211.

Signed-off-by: Sujith Manoharan <Sujith.Manoharan@atheros.com>
Signed-off-by: Jouni Malinen <Jouni.Malinen@Atheros.com>
Signed-off-by: Luis R. Rodriguez <lrodriguez@atheros.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

1 files changed, 30 insertions, 5 deletions

diff --git a/drivers/net/wireless/ath9k/hw.c b/drivers/net/wireless/ath9k/hw.c
index 272c75816609..62e44a0ef996 100644
--- a/drivers/net/wireless/ath9k/hw.c
+++ b/drivers/net/wireless/ath9k/hw.c
@@ -329,7 +329,7 @@ static void ath9k_hw_set_defaults(struct ath_hal *ah)
         ah->ah_config.ofdm_trig_high = 500;
         ah->ah_config.cck_trig_high = 200;
         ah->ah_config.cck_trig_low = 100;
-        ah->ah_config.enable_ani = 0;
+        ah->ah_config.enable_ani = 1;
         ah->ah_config.noise_immunity_level = 4;
         ah->ah_config.ofdm_weaksignal_det = 1;
         ah->ah_config.cck_weaksignal_thr = 0;
@@ -8405,23 +8405,48 @@ u32 ath9k_hw_mhz2ieee(struct ath_hal *ah, u32 freq, u32 flags)
         }
 }
 
-int16_t
+/* We can tune this as we go by monitoring really low values */
+#define ATH9K_NF_TOO_LOW        -60
+
+/* AR5416 may return very high value (like -31 dBm), in those cases the nf
+ * is incorrect and we should use the static NF value. Later we can try to
+ * find out why they are reporting these values */
+static bool ath9k_hw_nf_in_range(struct ath_hal *ah, s16 nf)
+{
+        if (nf > ATH9K_NF_TOO_LOW) {
+                DPRINTF(ah->ah_sc, ATH_DBG_NF_CAL,
+                         "%s: noise floor value detected (%d) is "
+                        "lower than what we think is a "
+                        "reasonable value (%d)\n",
+                         __func__, nf, ATH9K_NF_TOO_LOW);
+                return false;
+        }
+        return true;
+}
+
+s16
 ath9k_hw_getchan_noise(struct ath_hal *ah, struct ath9k_channel *chan)
 {
         struct ath9k_channel *ichan;
+        s16 nf;
 
         ichan = ath9k_regd_check_channel(ah, chan);
         if (ichan == NULL) {
                 DPRINTF(ah->ah_sc, ATH_DBG_NF_CAL,
                          "%s: invalid channel %u/0x%x; no mapping\n",
                          __func__, chan->channel, chan->channelFlags);
-                return 0;
+                return ATH_DEFAULT_NOISE_FLOOR;
         }
         if (ichan->rawNoiseFloor == 0) {
                 enum wireless_mode mode = ath9k_hw_chan2wmode(ah, chan);
-                return NOISE_FLOOR[mode];
+                nf = NOISE_FLOOR[mode];
         } else
-                return ichan->rawNoiseFloor;
+                nf = ichan->rawNoiseFloor;
+
+        if (!ath9k_hw_nf_in_range(ah, nf))
+                nf = ATH_DEFAULT_NOISE_FLOOR;
+
+        return nf;
 }
 
 bool ath9k_hw_set_tsfadjust(struct ath_hal *ah, u32 setting)