From 96ff56419504ac6a610ff1af42330e0423242e16 Mon Sep 17 00:00:00 2001 From: Johannes Berg Date: Fri, 30 Apr 2010 14:42:15 -0700 Subject: [PATCH] iwlwifi: work around passive scan issue 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 Signed-off-by: Reinette Chatre --- 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 6383d9f8c9b3..f4e59ae07f8e 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 5062f4ebb6a9..2367286eb74d 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 e276f2a4e835..2f47d9332bfc 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"); -- 2.20.1