mac80211: Support ht-cap over-rides.

This implements ht-cap over-rides for mac80211 drivers.
HT may be disabled, making an /a/b/g/n station act like an
a/b/g station.  HT40 may be disabled forcing the station to
be HT20 even if the AP and local hardware support HT40.

MAX-AMSDU may be disabled.
AMPDU-Density may be increased.
AMPDU-Factor may be decreased.

This has been successfully tested with ath9k using patched
wpa_supplicant and iw.

Signed-off-by: Ben Greear <greearb@candelatech.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

1 files changed, 12 insertions, 4 deletions

diff --git a/net/mac80211/work.c b/net/mac80211/work.c
index 3dd5a89e99a7..6884a2d986dc 100644
--- a/net/mac80211/work.c
+++ b/net/mac80211/work.c
@@ -94,7 +94,8 @@ static int ieee80211_compatible_rates(const u8 *supp_rates, int supp_rates_len,
 
 /* frame sending functions */
 
-static void ieee80211_add_ht_ie(struct sk_buff *skb, const u8 *ht_info_ie,
+static void ieee80211_add_ht_ie(struct ieee80211_sub_if_data *sdata,
+                                struct sk_buff *skb, const u8 *ht_info_ie,
                                 struct ieee80211_supported_band *sband,
                                 struct ieee80211_channel *channel,
                                 enum ieee80211_smps_mode smps)
@@ -102,7 +103,10 @@ static void ieee80211_add_ht_ie(struct sk_buff *skb, const u8 *ht_info_ie,
         struct ieee80211_ht_info *ht_info;
         u8 *pos;
         u32 flags = channel->flags;
-        u16 cap = sband->ht_cap.cap;
+        u16 cap;
+        struct ieee80211_sta_ht_cap ht_cap;
+
+        BUILD_BUG_ON(sizeof(ht_cap) != sizeof(sband->ht_cap));
 
         if (!sband->ht_cap.ht_supported)
                 return;
@@ -113,9 +117,13 @@ static void ieee80211_add_ht_ie(struct sk_buff *skb, const u8 *ht_info_ie,
         if (ht_info_ie[1] < sizeof(struct ieee80211_ht_info))
                 return;
 
+        memcpy(&ht_cap, &sband->ht_cap, sizeof(ht_cap));
+        ieee80211_apply_htcap_overrides(sdata, &ht_cap);
+
         ht_info = (struct ieee80211_ht_info *)(ht_info_ie + 2);
 
         /* determine capability flags */
+        cap = ht_cap.cap;
 
         switch (ht_info->ht_param & IEEE80211_HT_PARAM_CHA_SEC_OFFSET) {
         case IEEE80211_HT_PARAM_CHA_SEC_ABOVE:
@@ -154,7 +162,7 @@ static void ieee80211_add_ht_ie(struct sk_buff *skb, const u8 *ht_info_ie,
 
         /* reserve and fill IE */
         pos = skb_put(skb, sizeof(struct ieee80211_ht_cap) + 2);
-        ieee80211_ie_build_ht_cap(pos, sband, cap);
+        ieee80211_ie_build_ht_cap(pos, &ht_cap, cap);
 }
 
 static void ieee80211_send_assoc(struct ieee80211_sub_if_data *sdata,
@@ -329,7 +337,7 @@ static void ieee80211_send_assoc(struct ieee80211_sub_if_data *sdata,
 
         if (wk->assoc.use_11n && wk->assoc.wmm_used &&
             local->hw.queues >= 4)
-                ieee80211_add_ht_ie(skb, wk->assoc.ht_information_ie,
+                ieee80211_add_ht_ie(sdata, skb, wk->assoc.ht_information_ie,
                                     sband, wk->chan, wk->assoc.smps);
 
         /* if present, add any custom non-vendor IEs that go after HT */