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authorJohannes Berg <johannes.berg@intel.com>2011-02-25 12:24:11 +0100
committerJohn W. Linville <linville@tuxdriver.com>2011-02-25 15:33:39 -0500
commit850bedcc10377629ea88c96c07f8e1d0a99cf4ca (patch)
tree102aa7e024d291a71fc250c2b680e83f4f77e2ad
parent90b4ca9dba87bef9a3352c3d5bcab998be70fc4f (diff)
iwlagn: fix iwlagn_check_needed_chains
This function was intended to calculate the number of RX chains needed, but could only work where the AP's streams were asymmetric, i.e. 2 TX and 3 RX or similar. In the case where IEEE80211_HT_MCS_TX_RX_DIFF was not set, this function would calculate the wrong information. Additionally, mac80211 didn't pass through the required values at all, so it couldn't work anyway. Rewrite the logic in this function and add appropriate comments to make it readable. Signed-off-by: Johannes Berg <johannes.berg@intel.com> Signed-off-by: John W. Linville <linville@tuxdriver.com>
-rw-r--r--drivers/net/wireless/iwlwifi/iwl-agn-rxon.c58
1 files changed, 41 insertions, 17 deletions
diff --git a/drivers/net/wireless/iwlwifi/iwl-agn-rxon.c b/drivers/net/wireless/iwlwifi/iwl-agn-rxon.c
index 6c2adc58d654..dfdbea6e8f99 100644
--- a/drivers/net/wireless/iwlwifi/iwl-agn-rxon.c
+++ b/drivers/net/wireless/iwlwifi/iwl-agn-rxon.c
@@ -471,6 +471,7 @@ static void iwlagn_check_needed_chains(struct iwl_priv *priv,
struct iwl_rxon_context *tmp;
struct ieee80211_sta *sta;
struct iwl_ht_config *ht_conf = &priv->current_ht_config;
+ struct ieee80211_sta_ht_cap *ht_cap;
bool need_multiple;
lockdep_assert_held(&priv->mutex);
@@ -479,23 +480,7 @@ static void iwlagn_check_needed_chains(struct iwl_priv *priv,
case NL80211_IFTYPE_STATION:
rcu_read_lock();
sta = ieee80211_find_sta(vif, bss_conf->bssid);
- if (sta) {
- struct ieee80211_sta_ht_cap *ht_cap = &sta->ht_cap;
- int maxstreams;
-
- maxstreams = (ht_cap->mcs.tx_params &
- IEEE80211_HT_MCS_TX_MAX_STREAMS_MASK)
- >> IEEE80211_HT_MCS_TX_MAX_STREAMS_SHIFT;
- maxstreams += 1;
-
- need_multiple = true;
-
- if ((ht_cap->mcs.rx_mask[1] == 0) &&
- (ht_cap->mcs.rx_mask[2] == 0))
- need_multiple = false;
- if (maxstreams <= 1)
- need_multiple = false;
- } else {
+ if (!sta) {
/*
* If at all, this can only happen through a race
* when the AP disconnects us while we're still
@@ -503,7 +488,46 @@ static void iwlagn_check_needed_chains(struct iwl_priv *priv,
* will soon tell us about that.
*/
need_multiple = false;
+ rcu_read_unlock();
+ break;
+ }
+
+ ht_cap = &sta->ht_cap;
+
+ need_multiple = true;
+
+ /*
+ * If the peer advertises no support for receiving 2 and 3
+ * stream MCS rates, it can't be transmitting them either.
+ */
+ if (ht_cap->mcs.rx_mask[1] == 0 &&
+ ht_cap->mcs.rx_mask[2] == 0) {
+ need_multiple = false;
+ } else if (!(ht_cap->mcs.tx_params &
+ IEEE80211_HT_MCS_TX_DEFINED)) {
+ /* If it can't TX MCS at all ... */
+ need_multiple = false;
+ } else if (ht_cap->mcs.tx_params &
+ IEEE80211_HT_MCS_TX_RX_DIFF) {
+ int maxstreams;
+
+ /*
+ * But if it can receive them, it might still not
+ * be able to transmit them, which is what we need
+ * to check here -- so check the number of streams
+ * it advertises for TX (if different from RX).
+ */
+
+ maxstreams = (ht_cap->mcs.tx_params &
+ IEEE80211_HT_MCS_TX_MAX_STREAMS_MASK);
+ maxstreams >>=
+ IEEE80211_HT_MCS_TX_MAX_STREAMS_SHIFT;
+ maxstreams += 1;
+
+ if (maxstreams <= 1)
+ need_multiple = false;
}
+
rcu_read_unlock();
break;
case NL80211_IFTYPE_ADHOC: