+static bool carl9170_ampdu_check(struct ar9170 *ar, u8 *buf, u8 ms)
+{
+ __le16 fc;
+
+ if ((ms & AR9170_RX_STATUS_MPDU) == AR9170_RX_STATUS_MPDU_SINGLE) {
+ /*
+ * This frame is not part of an aMPDU.
+ * Therefore it is not subjected to any
+ * of the following content restrictions.
+ */
+ return true;
+ }
+
+ /*
+ * "802.11n - 7.4a.3 A-MPDU contents" describes in which contexts
+ * certain frame types can be part of an aMPDU.
+ *
+ * In order to keep the processing cost down, I opted for a
+ * stateless filter solely based on the frame control field.
+ */
+
+ fc = ((struct ieee80211_hdr *)buf)->frame_control;
+ if (ieee80211_is_data_qos(fc) && ieee80211_is_data_present(fc))
+ return true;
+
+ if (ieee80211_is_ack(fc) || ieee80211_is_back(fc) ||
+ ieee80211_is_back_req(fc))
+ return true;
+
+ if (ieee80211_is_action(fc))
+ return true;
+
+ return false;
+}
+