The new iwm(4) firmware (see [1]) scans 2GHz and 5 GHz bands in one go.
[1] http://marc.info/?l=openbsd-tech&m=146356530605833&w=2
Our net80211 stack isn't set up to handle this correctly.
With the new firmware (and diff from [1]), you'll see no scan results
at all if you run:
ifconfig iwm0 nwid some-nwid-that-doesnt-exist-on-2ghz
ifconfig iwm0 scan
This happens because the net80211 stack clears scan results from memory
before results are returned to ifconfig, and retries on a different band.
The driver however insists that it is already done scanning everything,
and does nothing (a SCAN->SCAN transition is a no-op in the driver).
So the second scan attempt times out, and ifconfig gets no results.
This diff adds a 'scan all bands' capability which the driver can advertise
to tell the net80211 layer that it should not retry the scan on a different
band. Setting this flag in the iwm(4) driver then fixes the issue.
(Note that the comment immediately below refers to a 'next mode' instead of
'next band' because it dates from a time when a mode implied a band, as in
11b -> 2GHz and 11a -> 5 GHz. Nowadays, we have 11n mode uses both bands.)
ok?
Index: ieee80211_node.c
===================================================================
RCS file: /cvs/src/sys/net80211/ieee80211_node.c,v
retrieving revision 1.102
diff -u -p -r1.102 ieee80211_node.c
--- ieee80211_node.c 18 May 2016 08:15:28 -0000 1.102
+++ ieee80211_node.c 20 May 2016 09:05:39 -0000
@@ -581,6 +581,10 @@ ieee80211_end_scan(struct ifnet *ifp)
goto wakeup;
}
#endif
+ /* If the device scans all bands at once, we're done. */
+ if (ic->ic_caps & IEEE80211_C_SCANALLBAND)
+ goto wakeup;
+
/*
* Scan the next mode if nothing has been found. This
* is necessary if the device supports different
Index: ieee80211_var.h
===================================================================
RCS file: /cvs/src/sys/net80211/ieee80211_var.h,v
retrieving revision 1.71
diff -u -p -r1.71 ieee80211_var.h
--- ieee80211_var.h 25 Jan 2016 11:27:11 -0000 1.71
+++ ieee80211_var.h 20 May 2016 08:56:14 -0000
@@ -369,6 +369,7 @@ extern struct ieee80211com_head ieee8021
#define IEEE80211_C_RSN 0x00001000 /* CAPABILITY: RSN
avail */
#define IEEE80211_C_MFP 0x00002000 /* CAPABILITY: MFP
avail */
#define IEEE80211_C_RAWCTL 0x00004000 /* CAPABILITY: raw ctl */
+#define IEEE80211_C_SCANALLBAND 0x00008000 /* CAPABILITY: scan all
bands */
/* flags for ieee80211_fix_rate() */
#define IEEE80211_F_DOSORT 0x00000001 /* sort rate list */
