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authorFelix Fietkau <nbd@openwrt.org>2010-08-02 09:53:14 -0400
committerJohn W. Linville <linville@tuxdriver.com>2010-08-16 15:26:39 -0400
commit70cf15335eb35d562a4ec6d8860611c87f775cf2 (patch)
tree174a5e11b2e4269695c0870772fbfca42be4e1bb /drivers/net/wireless/ath/ath9k/hw.h
parent2292ca6d783d3c79b58591bb3ee795bf0144e5ff (diff)
ath9k: use AP beacon miss as a trigger for fast recalibration
When beacons get stuck in AP mode, the most likely cause is interference. Such interference can often go on for a while, and too many consecutive beacon misses can lead to connected clients getting dropped. Since connected clients might not be subjected to the same interference if that happens to be very local, the AP should try to deal with it as good as it can. One way to do this is to trigger an NF calibration with automatic baseband update right after the beacon miss. In my tests with very strong interference, this allowed the AP to continue transmitting beacons after only 2-3 misses, which allows a normal client to stay connected. With some of the newer - really sensitive - chips, the maximum noise floor limit is very low, which can be problematic during very strong interference. To avoid an endless loop of stuck beacons -> nfcal -> periodic calibration -> stuck beacons, the beacon miss event also sets a flag, which allows the calibration code to bypass the chip specific maximum NF value. This flag is automatically cleared, as soon as the first NF median goes back below the limits for all chains. In my tests, this allowed an ath9k AP to survive very strong interference (measured NF: -68, or sometimes even higher) without losing connectivity to its clients. Even under these conditions, I was able to transmit several mbits/s through the interface. Signed-off-by: Felix Fietkau <nbd@openwrt.org> Signed-off-by: John W. Linville <linville@tuxdriver.com>
Diffstat (limited to 'drivers/net/wireless/ath/ath9k/hw.h')
-rw-r--r--drivers/net/wireless/ath/ath9k/hw.h1
1 files changed, 1 insertions, 0 deletions
diff --git a/drivers/net/wireless/ath/ath9k/hw.h b/drivers/net/wireless/ath/ath9k/hw.h
index 399f7c1283cd..1601dd439890 100644
--- a/drivers/net/wireless/ath/ath9k/hw.h
+++ b/drivers/net/wireless/ath/ath9k/hw.h
@@ -355,6 +355,7 @@ struct ath9k_hw_cal_data {
355 int16_t rawNoiseFloor; 355 int16_t rawNoiseFloor;
356 bool paprd_done; 356 bool paprd_done;
357 bool nfcal_pending; 357 bool nfcal_pending;
358 bool nfcal_interference;
358 u16 small_signal_gain[AR9300_MAX_CHAINS]; 359 u16 small_signal_gain[AR9300_MAX_CHAINS];
359 u32 pa_table[AR9300_MAX_CHAINS][PAPRD_TABLE_SZ]; 360 u32 pa_table[AR9300_MAX_CHAINS][PAPRD_TABLE_SZ];
360 struct ath9k_nfcal_hist nfCalHist[NUM_NF_READINGS]; 361 struct ath9k_nfcal_hist nfCalHist[NUM_NF_READINGS];