mac80211: track number of spatial streams

With VHT, a station can change the number of spatial
streams it can receive on the fly, not unlike spatial
multiplexing in HT. Prepare for that by tracking the
maximum number of spatial streams it can receive when
the connection is established.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>

1 files changed, 41 insertions, 0 deletions

diff --git a/net/mac80211/vht.c b/net/mac80211/vht.c
index 0fc9a2fb8d53..67436e3efbbd 100644
--- a/net/mac80211/vht.c
+++ b/net/mac80211/vht.c
@@ -74,3 +74,44 @@ enum ieee80211_sta_rx_bandwidth ieee80211_sta_cur_vht_bw(struct sta_info *sta)
                 return IEEE80211_STA_RX_BW_80;
         }
 }
+
+void ieee80211_sta_set_rx_nss(struct sta_info *sta)
+{
+        u8 ht_rx_nss = 0, vht_rx_nss = 0;
+
+        /* if we received a notification already don't overwrite it */
+        if (sta->sta.rx_nss)
+                return;
+
+        if (sta->sta.ht_cap.ht_supported) {
+                if (sta->sta.ht_cap.mcs.rx_mask[0])
+                        ht_rx_nss++;
+                if (sta->sta.ht_cap.mcs.rx_mask[1])
+                        ht_rx_nss++;
+                if (sta->sta.ht_cap.mcs.rx_mask[2])
+                        ht_rx_nss++;
+                if (sta->sta.ht_cap.mcs.rx_mask[3])
+                        ht_rx_nss++;
+                /* FIXME: consider rx_highest? */
+        }
+
+        if (sta->sta.vht_cap.vht_supported) {
+                int i;
+                u16 rx_mcs_map;
+
+                rx_mcs_map = le16_to_cpu(sta->sta.vht_cap.vht_mcs.rx_mcs_map);
+
+                for (i = 7; i >= 0; i--) {
+                        u8 mcs = (rx_mcs_map >> (2 * i)) & 3;
+
+                        if (mcs != IEEE80211_VHT_MCS_NOT_SUPPORTED) {
+                                vht_rx_nss = i + 1;
+                                break;
+                        }
+                }
+                /* FIXME: consider rx_highest? */
+        }
+
+        ht_rx_nss = max(ht_rx_nss, vht_rx_nss);
+        sta->sta.rx_nss = max_t(u8, 1, ht_rx_nss);
+}