mac80211: introduce capability flags for VHT EXT NSS support

Depending on whether or not rate control supports selecting
rates depending on the bandwidth, we can use VHT extended
NSS support. In essence, this is dot11VHTExtendedNSSBWCapable
from the spec, since depending on that we'll need to parse
the bandwidth.

If needed, also set/clear the VHT Capability Element bit for
this capability so that we don't advertise it erroneously or
don't advertise it when we actually use it.

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

1 files changed, 22 insertions, 0 deletions

diff --git a/include/net/mac80211.h b/include/net/mac80211.h
index 03e1dfd311f7..00e2e9909d45 100644
--- a/include/net/mac80211.h
+++ b/include/net/mac80211.h
@@ -2137,6 +2137,12 @@ struct ieee80211_txq {
  * @IEEE80211_HW_BUFF_MMPDU_TXQ: use the TXQ for bufferable MMPDUs, this of
  *	course requires the driver to use TXQs to start with.
  *
+ * @IEEE80211_HW_SUPPORTS_VHT_EXT_NSS_BW: (Hardware) rate control supports VHT
+ *	extended NSS BW (dot11VHTExtendedNSSBWCapable). This flag will be set if
+ *	the selected rate control algorithm sets %RATE_CTRL_CAPA_VHT_EXT_NSS_BW
+ *	but if the rate control is built-in then it must be set by the driver.
+ *	See also the documentation for that flag.
+ *
  * @NUM_IEEE80211_HW_FLAGS: number of hardware flags, used for sizing arrays
  */
 enum ieee80211_hw_flags {
@@ -2183,6 +2189,7 @@ enum ieee80211_hw_flags {
 	IEEE80211_HW_DEAUTH_NEED_MGD_TX_PREP,
 	IEEE80211_HW_DOESNT_SUPPORT_QOS_NDP,
 	IEEE80211_HW_BUFF_MMPDU_TXQ,
+	IEEE80211_HW_SUPPORTS_VHT_EXT_NSS_BW,
 
 	/* keep last, obviously */
 	NUM_IEEE80211_HW_FLAGS
@@ -5655,7 +5662,22 @@ struct ieee80211_tx_rate_control {
 	bool bss;
 };
 
+/**
+ * enum rate_control_capabilities - rate control capabilities
+ */
+enum rate_control_capabilities {
+	/**
+	 * @RATE_CTRL_CAPA_VHT_EXT_NSS_BW:
+	 * Support for extended NSS BW support (dot11VHTExtendedNSSCapable)
+	 * Note that this is only looked at if the minimum number of chains
+	 * that the AP uses is < the number of TX chains the hardware has,
+	 * otherwise the NSS difference doesn't bother us.
+	 */
+	RATE_CTRL_CAPA_VHT_EXT_NSS_BW = BIT(0),
+};
+
 struct rate_control_ops {
+	unsigned long capa;
 	const char *name;
 	void *(*alloc)(struct ieee80211_hw *hw, struct dentry *debugfsdir);
 	void (*free)(void *priv);