Do not ask iwx(4) firmware to send probe requests on passive channels.

This seems to fix a problem where firmware becomes unresponsive after
association and eventually raises a fatal error. iwx(4) already has a
workaround in place for this: We always ask firmware to perform a
passive scan, on any channel.
This change is a better fix from iwm(4) CVS commit jJFMeXcos9GOqFQz.
However, the current workaround will stay in place for now, until we
have evidence that active scanning is working on iwx(4) devices.
I will try to organize an out-of-tree round of testing for this.

diff --git a/sys/dev/pci/if_iwx.c b/sys/dev/pci/if_iwx.c
index b8aa252..785509e 100644 (file)
--- a/sys/dev/pci/if_iwx.c
+++ b/sys/dev/pci/if_iwx.c
@@ -1,4 +1,4 @@
-/*     $OpenBSD: if_iwx.c,v 1.68 2021/07/18 12:39:16 stsp Exp $        */
+/*     $OpenBSD: if_iwx.c,v 1.69 2021/07/18 13:07:13 stsp Exp $        */
 
 /*
  * Copyright (c) 2014, 2016 genua gmbh <info@genua.de>
@@ -5334,7 +5334,12 @@ iwx_umac_scan_fill_channels(struct iwx_softc *sc,
                        chan->v1.iter_count = 1;
                        chan->v1.iter_interval = htole16(0);
                }
-               if (n_ssids != 0 && !bgscan)
+               /*
+                * Firmware may become unresponsive when asked to send
+                * a directed probe request on a passive channel.
+                */
+               if (n_ssids != 0 && !bgscan &&
+                   (c->ic_flags & IEEE80211_CHAN_PASSIVE) == 0)
                        chan->flags = htole32(1 << 0); /* select SSID 0 */
                chan++;
                nchan++;