ath9k returns a wrong RSSI value for frames received in a 30ms time
window after a channel change. The correct value is typically 10dB
below the returned value.
This was found with a Atheros AR9300 Rev:3 chip (WLE350NX / JWX6083
cards), during offchannel scans.
Mark the signal value as invalid in this case.
Signed-off-by: Jean Pierre TOSONI <jp.tosoni@xxxxxxxxx>
---
V2: replace LEDE patch with due kernel patch (with excuses to Kalle Valo)
drivers/net/wireless/ath/ath9k/ani.c | 1 +
drivers/net/wireless/ath/ath9k/common.c | 10 ++++++++++
drivers/net/wireless/ath/ath9k/hw.h | 1 +
3 files changed, 12 insertions(+), 0 deletions(-)
diff --git a/drivers/net/wireless/ath/ath9k/ani.c b/drivers/net/wireless/ath/ath9k/ani.c
index 5214dd7..a7e07ed 100644
--- a/drivers/net/wireless/ath/ath9k/ani.c
+++ b/drivers/net/wireless/ath/ath9k/ani.c
@@ -317,6 +317,7 @@ void ath9k_ani_reset(struct ath_hw *ah, bool is_scanning)
return;
BUG_ON(aniState == NULL);
+ ah->chan_stable_time = jiffies + (30*HZ)/1000; /* 30ms */
ah->stats.ast_ani_reset++;
ofdm_nil = max_t(int, ATH9K_ANI_OFDM_DEF_LEVEL,
diff --git a/drivers/net/wireless/ath/ath9k/common.c b/drivers/net/wireless/ath/ath9k/common.c
index 099f3d4..7e5f7a3 100644
--- a/drivers/net/wireless/ath/ath9k/common.c
+++ b/drivers/net/wireless/ath/ath9k/common.c
@@ -221,6 +221,16 @@ void ath9k_cmn_process_rssi(struct ath_common *common,
int i, j;
/*
+ * RSSI is not available before 30ms after reset on ath9k.
+ */
+ if (time_before(jiffies, ah->chan_stable_time)) {
+ ath_dbg(common, ANY, "early frame rssi=%d\n",rx_stats->rs_rssi);
+ rxs->flag |= RX_FLAG_NO_SIGNAL_VAL;
+ return;
+ }
+ ah->chan_stable_time = jiffies; /* advance stable time to cop with jiffies wraparound */
+
+ /*
* RSSI is not available for subframes in an A-MPDU.
*/
if (rx_stats->rs_moreaggr) {
diff --git a/drivers/net/wireless/ath/ath9k/hw.h b/drivers/net/wireless/ath/ath9k/hw.h
index 9804a24..ec07da9 100644
--- a/drivers/net/wireless/ath/ath9k/hw.h
+++ b/drivers/net/wireless/ath/ath9k/hw.h
@@ -809,6 +809,7 @@ struct ath_hw {
bool reset_power_on;
bool htc_reset_init;
+ unsigned long chan_stable_time;
enum nl80211_iftype opmode;
enum ath9k_power_mode power_mode;
--
1.7.2.5
