+ * @tx_sync: Called before a frame is sent to an AP/GO. In the GO case, the
+ * driver should sync with the GO's powersaving so the device doesn't
+ * transmit the frame while the GO is asleep. In the regular AP case
+ * it may be used by drivers for devices implementing other restrictions
+ * on talking to APs, e.g. due to regulatory enforcement or just HW
+ * restrictions.
+ * This function is called for every authentication, association and
+ * action frame separately since applications might attempt to auth
+ * with multiple APs before chosing one to associate to. If it returns
+ * an error, the corresponding authentication, association or frame
+ * transmission is aborted and reported as having failed. It is always
+ * called after tuning to the correct channel.
+ * The callback might be called multiple times before @finish_tx_sync
+ * (but @finish_tx_sync will be called once for each) but in practice
+ * this is unlikely to happen. It can also refuse in that case if the
+ * driver cannot handle that situation.
+ * This callback can sleep.
+ * @finish_tx_sync: Called as a counterpart to @tx_sync, unless that returned
+ * an error. This callback can sleep.
+ *