mac80211: allow the driver to advertise A-MSDU within A-MPDU Rx support

Drivers may be interested in receiving A-MSDU within A-MDPU.
Not all the devices may be able to do so, make it configurable.

Signed-off-by: Emmanuel Grumbach <[e-mail]>
Signed-off-by: Johannes Berg <[e-mail]>

include/net/mac80211.h

···
  * @IEEE80211_HW_TDLS_WIDER_BW: The device/driver supports wider bandwidth
  *	than then BSS bandwidth for a TDLS link on the base channel.
  *
+ * @IEEE80211_HW_SUPPORTS_AMSDU_IN_AMPDU: The driver supports receiving A-MSDUs
+ *	within A-MPDU.
+ *
  * @NUM_IEEE80211_HW_FLAGS: number of hardware flags, used for sizing arrays
  */
 enum ieee80211_hw_flags {
···
 	IEEE80211_HW_SUPPORTS_CLONED_SKBS,
 	IEEE80211_HW_SINGLE_SCAN_ON_ALL_BANDS,
 	IEEE80211_HW_TDLS_WIDER_BW,
+	IEEE80211_HW_SUPPORTS_AMSDU_IN_AMPDU,
 
 	/* keep last, obviously */
 	NUM_IEEE80211_HW_FLAGS

net/mac80211/agg-rx.c

···
 	struct ieee80211_local *local = sdata->local;
 	struct sk_buff *skb;
 	struct ieee80211_mgmt *mgmt;
+	bool amsdu = ieee80211_hw_check(&local->hw, SUPPORTS_AMSDU_IN_AMPDU);
 	u16 capab;
 
 	skb = dev_alloc_skb(sizeof(*mgmt) + local->hw.extra_tx_headroom);
···
 	mgmt->u.action.u.addba_resp.action_code = WLAN_ACTION_ADDBA_RESP;
 	mgmt->u.action.u.addba_resp.dialog_token = dialog_token;
 
-	capab = (u16)(policy << 1);	/* bit 1 aggregation policy */
+	capab = (u16)(amsdu << 0);	/* bit 0 A-MSDU support */
+	capab |= (u16)(policy << 1);	/* bit 1 aggregation policy */
 	capab |= (u16)(tid << 2); 	/* bit 5:2 TID number */
 	capab |= (u16)(buf_size << 6);	/* bit 15:6 max size of aggregation */
 

net/mac80211/debugfs.c

···
 	FLAG(SUPPORTS_CLONED_SKBS),
 	FLAG(SINGLE_SCAN_ON_ALL_BANDS),
 	FLAG(TDLS_WIDER_BW),
+	FLAG(SUPPORTS_AMSDU_IN_AMPDU),
 
 	/* keep last for the build bug below */
 	(void *)0x1