From: Johannes Berg <johannes.berg@xxxxxxxxx>
Some firmware versions don't behave properly when
passive scanning is requested on radar channels
without enabling active scanning on receiving a
good frame. Work around that issue by asking the
firmware to only enable the active scanning after
receiving a huge number of good frames, a number
that can never be reached during our dwell time.
Signed-off-by: Johannes Berg <johannes.berg@xxxxxxxxx>
Signed-off-by: Reinette Chatre <reinette.chatre@xxxxxxxxx>
---
This patch is also available from wireless-2.6 branch on
git://git.kernel.org/pub/scm/linux/kernel/git/iwlwifi/iwlwifi-2.6.git
drivers/net/wireless/iwlwifi/iwl-commands.h | 4 +++-
drivers/net/wireless/iwlwifi/iwl-scan.c | 23 ++++++++++++++++++-----
drivers/net/wireless/iwlwifi/iwl3945-base.c | 3 ++-
3 files changed, 23 insertions(+), 7 deletions(-)
diff --git a/drivers/net/wireless/iwlwifi/iwl-commands.h b/drivers/net/wireless/iwlwifi/iwl-commands.h
index 6383d9f..f4e59ae 100644
--- a/drivers/net/wireless/iwlwifi/iwl-commands.h
+++ b/drivers/net/wireless/iwlwifi/iwl-commands.h
@@ -2621,7 +2621,9 @@ struct iwl_ssid_ie {
#define PROBE_OPTION_MAX_3945 4
#define PROBE_OPTION_MAX 20
#define TX_CMD_LIFE_TIME_INFINITE cpu_to_le32(0xFFFFFFFF)
-#define IWL_GOOD_CRC_TH cpu_to_le16(1)
+#define IWL_GOOD_CRC_TH_DISABLED 0
+#define IWL_GOOD_CRC_TH_DEFAULT cpu_to_le16(1)
+#define IWL_GOOD_CRC_TH_NEVER cpu_to_le16(0xffff)
#define IWL_MAX_SCAN_SIZE 1024
#define IWL_MAX_CMD_SIZE 4096
#define IWL_MAX_PROBE_REQUEST 200
diff --git a/drivers/net/wireless/iwlwifi/iwl-scan.c b/drivers/net/wireless/iwlwifi/iwl-scan.c
index 5062f4e..2367286 100644
--- a/drivers/net/wireless/iwlwifi/iwl-scan.c
+++ b/drivers/net/wireless/iwlwifi/iwl-scan.c
@@ -812,16 +812,29 @@ static void iwl_bg_request_scan(struct work_struct *data)
rate = IWL_RATE_1M_PLCP;
rate_flags = RATE_MCS_CCK_MSK;
}
- scan->good_CRC_th = 0;
+ scan->good_CRC_th = IWL_GOOD_CRC_TH_DISABLED;
} else if (priv->scan_bands & BIT(IEEE80211_BAND_5GHZ)) {
band = IEEE80211_BAND_5GHZ;
rate = IWL_RATE_6M_PLCP;
/*
- * If active scaning is requested but a certain channel
- * is marked passive, we can do active scanning if we
- * detect transmissions.
+ * If active scanning is requested but a certain channel is
+ * marked passive, we can do active scanning if we detect
+ * transmissions.
+ *
+ * There is an issue with some firmware versions that triggers
+ * a sysassert on a "good CRC threshold" of zero (== disabled),
+ * on a radar channel even though this means that we should NOT
+ * send probes.
+ *
+ * The "good CRC threshold" is the number of frames that we
+ * need to receive during our dwell time on a channel before
+ * sending out probes -- setting this to a huge value will
+ * mean we never reach it, but at the same time work around
+ * the aforementioned issue. Thus use IWL_GOOD_CRC_TH_NEVER
+ * here instead of IWL_GOOD_CRC_TH_DISABLED.
*/
- scan->good_CRC_th = is_active ? IWL_GOOD_CRC_TH : 0;
+ scan->good_CRC_th = is_active ? IWL_GOOD_CRC_TH_DEFAULT :
+ IWL_GOOD_CRC_TH_NEVER;
/* Force use of chains B and C (0x6) for scan Rx for 4965
* Avoid A (0x1) because of its off-channel reception on A-band.
diff --git a/drivers/net/wireless/iwlwifi/iwl3945-base.c b/drivers/net/wireless/iwlwifi/iwl3945-base.c
index e276f2a..2f47d93 100644
--- a/drivers/net/wireless/iwlwifi/iwl3945-base.c
+++ b/drivers/net/wireless/iwlwifi/iwl3945-base.c
@@ -2966,7 +2966,8 @@ static void iwl3945_bg_request_scan(struct work_struct *data)
* is marked passive, we can do active scanning if we
* detect transmissions.
*/
- scan->good_CRC_th = is_active ? IWL_GOOD_CRC_TH : 0;
+ scan->good_CRC_th = is_active ? IWL_GOOD_CRC_TH_DEFAULT :
+ IWL_GOOD_CRC_TH_DISABLED;
band = IEEE80211_BAND_5GHZ;
} else {
IWL_WARN(priv, "Invalid scan band count\n");
--
1.6.3.3
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