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authorChristian Lamparter <chunkeey@googlemail.com>2012-09-11 23:18:34 +0200
committerJohn W. Linville <linville@tuxdriver.com>2012-10-29 15:18:04 -0400
commite0509d3bdd7365d06c9bf570bf9f118cae6cbd58 (patch)
treee2a5d8d6d5c8e6a5558d11662853d4cd893f30a0 /drivers/net/wireless/ath/carl9170
parente298c79efcf7b88fded994a03375589d8b726ce7 (diff)
carl9170: fix spurious transmissions in sniffer mode
Several people have complained about an unusual and undocumented feature of the AR9170 hardware: In siffer mode, the hardware generates spurious ACK frames for every received frame... even broadcasts. The reason for this malfunction is unknown: <http://marc.info/?l=linux-wireless&m=134517238506033> But there's a workaround: Instead of the special sniffer mode, the hardware will be put into station mode and all rx filters are disabled. Reported-by: Johannes Berg <johannes@sipsolutions.net> Reported-by: Marco Fonseca <marco@tampabay.rr.com> Reported-by: Janusz Dziedzic <janusz.dziedzic@gmail.com> Signed-off-by: Christian Lamparter <chunkeey@googlemail.com> Signed-off-by: John W. Linville <linville@tuxdriver.com>
Diffstat (limited to 'drivers/net/wireless/ath/carl9170')
-rw-r--r--drivers/net/wireless/ath/carl9170/mac.c21
1 files changed, 18 insertions, 3 deletions
diff --git a/drivers/net/wireless/ath/carl9170/mac.c b/drivers/net/wireless/ath/carl9170/mac.c
index e3b1b6e8776..24d75ab94f0 100644
--- a/drivers/net/wireless/ath/carl9170/mac.c
+++ b/drivers/net/wireless/ath/carl9170/mac.c
@@ -343,7 +343,24 @@ int carl9170_set_operating_mode(struct ar9170 *ar)
break;
}
} else {
- mac_addr = NULL;
+ /*
+ * Enable monitor mode
+ *
+ * rx_ctrl |= AR9170_MAC_RX_CTRL_ACK_IN_SNIFFER;
+ * sniffer |= AR9170_MAC_SNIFFER_ENABLE_PROMISC;
+ *
+ * When the hardware is in SNIFFER_PROMISC mode,
+ * it generates spurious ACKs for every incoming
+ * frame. This confuses every peer in the
+ * vicinity and the network throughput will suffer
+ * badly.
+ *
+ * Hence, the hardware will be put into station
+ * mode and just the rx filters are disabled.
+ */
+ cam_mode |= AR9170_MAC_CAM_STA;
+ rx_ctrl |= AR9170_MAC_RX_CTRL_PASS_TO_HOST;
+ mac_addr = common->macaddr;
bssid = NULL;
}
rcu_read_unlock();
@@ -355,8 +372,6 @@ int carl9170_set_operating_mode(struct ar9170 *ar)
enc_mode |= AR9170_MAC_ENCRYPTION_RX_SOFTWARE;
if (ar->sniffer_enabled) {
- rx_ctrl |= AR9170_MAC_RX_CTRL_ACK_IN_SNIFFER;
- sniffer |= AR9170_MAC_SNIFFER_ENABLE_PROMISC;
enc_mode |= AR9170_MAC_ENCRYPTION_RX_SOFTWARE;
}