On Tuesday, June 04, 2013 09:30:23 PM Jouni Malinen wrote: > On Tue, Jun 04, 2013 at 07:47:20PM +0300, Vladimir Kondratiev wrote: > > I am a bit confused. I supposed that if devices A and B (not in a group yet) > > try to discover each other, it works like the following > > > > A ---- probe-req ---> B (now B knows A) > > A <--- probe-resp ---- B (now A knows B) > > This depends on what exactly you mean with "discover". Sure, it is known > that there is a P2P peer in the environment if a Probe Request frame > with P2P IE is received from it. However, that does not necessarily mean > we know enough of that peer to initiate new P2P operations. > > > But if device is discovered by probe-resp only, it mean this should be > > > > A ---- probe-req ---> B > > A <--- probe-resp ---- B (now A knows B) > > A <--- probe-req ---- B > > A ---- probe-resp ---> B (now B knows A) > > Probe Response frames include more information about the peer and that > allows wpa_supplicant to complete the peer entry. This is the point when > the peer is fully known and indicated to upper layers. The Probe Request > frame RX case is just used internally within wpa_supplicant. (For > completeness, number of other frames, i.e., P2P Action frames, can also > complete the P2P peer entry, so this does not need to be Probe > Response). Thanks for clarification. So, I see that wpa_s wants all probe responses and may want either all or selected probes, depending on the driver's capability (NL80211_FEATURE_P2P_PROBE_RESP_OFFLOAD) and its own reasons. Then, I think it would be appropriate to say following in the comment for start_p2p_find (no code changes, it is only expectations for the friver behavior): ---cut--- While performing P2P discovery, driver should report all received probe-request and probe-response frames via cfg80211_rx_mgmt, accordingly to the rx mgmt filter, as set by mgmt_frame_register(). When reporting probes, driver/firmware may do its best to filter out probes that would not be replied with probe-resp accordingly to the P2P rules for active device configuration. ---cut--- This makes possible for wpa_s to choose exact configuration, and good power saving is possible provided firmware answer probes. Comments? Thanks, Vladimir -- To unsubscribe from this list: send the line "unsubscribe linux-wireless" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
