madwifi: add an optional background scanning threshold triggered by low rssi

(useful for passing updated scan results to the wpa_supplicant ahead of
time, before losing connectivity entirely)


git-svn-id: svn://svn.openwrt.org/openwrt/trunk@11794 3c298f89-4303-0410-b956-a3cf2f4a3e73

1 files changed, 127 insertions, 0 deletions

diff --git a/package/madwifi/patches/357-bgscan_thresh.patch b/package/madwifi/patches/357-bgscan_thresh.patch
new file mode 100644
index 000000000..e0d5752b3
--- /dev/null
+++ b/package/madwifi/patches/357-bgscan_thresh.patch
@@ -0,0 +1,127 @@
+Add an optional background scanning threshold triggered by low rssi
+(useful for passing updated scan results to the supplicant ahead of
+time, before losing connectivity entirely)
+
+Signed-off-by: Felix Fietkau <nbd@openwrt.org>
+
+--- a/net80211/ieee80211_ioctl.h
++++ b/net80211/ieee80211_ioctl.h
+@@ -646,6 +646,7 @@
+ 	IEEE80211_PARAM_MINRATE			= 76,	/* Maximum rate (by table index) */
+ 	IEEE80211_PARAM_PROTMODE_RSSI		= 77,	/* RSSI Threshold for enabling protection mode */
+ 	IEEE80211_PARAM_PROTMODE_TIMEOUT	= 78,	/* Timeout for expiring protection mode */
++	IEEE80211_PARAM_BGSCAN_THRESH		= 79,	/* bg scan rssi threshold */
+ };
+ 
+ #define	SIOCG80211STATS			(SIOCDEVPRIVATE+2)
+--- a/net80211/ieee80211_var.h
++++ b/net80211/ieee80211_var.h
+@@ -92,6 +92,8 @@
+ #define	IEEE80211_BGSCAN_IDLE_MIN	100	/* min idle time (ms) */
+ #define	IEEE80211_BGSCAN_IDLE_DEFAULT	250	/* default idle time (ms) */
+ 
++#define IEEE80211_BGSCAN_TRIGGER_INTVL 20 /* min trigger interval for thresh based bgscan (secs) */
++
+ #define IEEE80211_COVERAGE_CLASS_MAX	31	/* max coverage class */
+ #define IEEE80211_REGCLASSIDS_MAX	10	/* max regclass id list */
+ 
+@@ -219,6 +221,9 @@
+ 	u_int8_t iv_nickname[IEEE80211_NWID_LEN];
+ 	u_int iv_bgscanidle;				/* bg scan idle threshold */
+ 	u_int iv_bgscanintvl;				/* bg scan min interval */
++	u_int iv_bgscanthr;					/* bg scan rssi threshold */
++	u_int iv_bgscantrintvl;				/* bg scan trigger interval */
++	unsigned long iv_bgscanthr_next;		/* last trigger for bgscan */
+ 	u_int iv_scanvalid;				/* scan cache valid threshold */
+ 	struct ieee80211_roam iv_roam;			/* sta-mode roaming state */
+ 
+@@ -608,6 +613,7 @@
+ #define IEEE80211_FEXT_SWBMISS		0x00000400	/* CONF: use software beacon timer */
+ #define IEEE80211_FEXT_DROPUNENC_EAPOL	0x00000800	/* CONF: drop unencrypted eapol frames */
+ #define IEEE80211_FEXT_APPIE_UPDATE	0x00001000	/* STATE: beacon APP IE updated */
++#define IEEE80211_FEXT_BGSCAN_THR	0x00002000	/* bgscan due to low rssi */
+ 
+ #define IEEE80211_COM_UAPSD_ENABLE(_ic)		((_ic)->ic_flags_ext |= IEEE80211_FEXT_UAPSD)
+ #define IEEE80211_COM_UAPSD_DISABLE(_ic)	((_ic)->ic_flags_ext &= ~IEEE80211_FEXT_UAPSD)
+--- a/net80211/ieee80211_wireless.c
++++ b/net80211/ieee80211_wireless.c
+@@ -2744,6 +2744,9 @@
+ 		else
+ 			retv = EINVAL;
+ 		break;
++	case IEEE80211_PARAM_BGSCAN_THRESH:
++		vap->iv_bgscanthr = value;
++		break;
+ 	case IEEE80211_PARAM_MCAST_RATE:
+ 		/* units are in KILObits per second */
+ 		if (value >= 256 && value <= 54000)
+@@ -3144,6 +3147,9 @@
+ 	case IEEE80211_PARAM_BGSCAN_INTERVAL:
+ 		param[0] = vap->iv_bgscanintvl / HZ;	/* seconds */
+ 		break;
++	case IEEE80211_PARAM_BGSCAN_THRESH:
++		param[0] = vap->iv_bgscanthr;	/* rssi */
++		break;
+ 	case IEEE80211_PARAM_MCAST_RATE:
+ 		param[0] = vap->iv_mcast_rate;	/* seconds */
+ 		break;
+@@ -5666,6 +5672,10 @@
+ 	  IW_PRIV_TYPE_INT | IW_PRIV_SIZE_FIXED | 1, 0, "bgscanintvl" },
+ 	{ IEEE80211_PARAM_BGSCAN_INTERVAL,
+ 	  0, IW_PRIV_TYPE_INT | IW_PRIV_SIZE_FIXED | 1, "get_bgscanintvl" },
++	{ IEEE80211_PARAM_BGSCAN_THRESH,
++	  IW_PRIV_TYPE_INT | IW_PRIV_SIZE_FIXED | 1, 0, "bgscanthr" },
++	{ IEEE80211_PARAM_BGSCAN_THRESH,
++	  0, IW_PRIV_TYPE_INT | IW_PRIV_SIZE_FIXED | 1, "get_bgscanthr" },
+ 	{ IEEE80211_PARAM_MCAST_RATE,
+ 	  IW_PRIV_TYPE_INT | IW_PRIV_SIZE_FIXED | 1, 0, "mcast_rate" },
+ 	{ IEEE80211_PARAM_MCAST_RATE,
+--- a/net80211/ieee80211_input.c
++++ b/net80211/ieee80211_input.c
+@@ -3013,8 +3013,10 @@
+ {
+ 	struct ieee80211com *ic = vap->iv_ic;
+ 
++	vap->iv_bgscantrintvl = (vap->iv_bgscantrintvl + 1) % 4;
+ 	return ((ic->ic_flags_ext & IEEE80211_FEXT_BGSCAN) &&
+-		time_after(jiffies, ic->ic_lastdata + vap->iv_bgscanidle));
++		(((ic->ic_flags_ext & IEEE80211_FEXT_BGSCAN_THR) && !vap->iv_bgscantrintvl) ||
++			time_after(jiffies, ic->ic_lastdata + vap->iv_bgscanidle)));
+ }
+ 
+ static __inline int
+@@ -3258,6 +3260,23 @@
+ 			/* record tsf of last beacon */
+ 			memcpy(ni->ni_tstamp.data, scan.tstamp,
+ 				sizeof(ni->ni_tstamp));
++
++			/* When rssi is low, start doing bgscans more frequently to allow
++			 * the supplicant to make a better switching decision */
++			if ((rssi < vap->iv_bgscanthr) &&
++					(!vap->iv_bgscanthr_next ||
++						!time_before(jiffies, vap->iv_bgscanthr_next)) &&
++					!(ic->ic_flags & IEEE80211_F_SCAN)) {
++				int ret;
++
++				ic->ic_lastdata = 0;
++				ic->ic_lastscan = 0;
++				ic->ic_flags_ext |= IEEE80211_FEXT_BGSCAN_THR;
++				ret = ieee80211_bg_scan(vap);
++				if (ret)
++					vap->iv_bgscanthr_next = jiffies + msecs_to_jiffies(IEEE80211_BGSCAN_TRIGGER_INTVL * 1000);
++			}
++
+ 			if (ni->ni_intval != scan.bintval) {
+ 				IEEE80211_NOTE(vap, IEEE80211_MSG_ASSOC, ni,
+ 						"beacon interval divergence: "
+--- a/net80211/ieee80211_scan.c
++++ b/net80211/ieee80211_scan.c
+@@ -782,7 +782,7 @@
+ 				ieee80211_sta_pwrsave(vap, 0);
+ 				if (ss->ss_next >= ss->ss_last) {
+ 					ieee80211_notify_scan_done(vap);
+-					ic->ic_flags_ext &= ~IEEE80211_FEXT_BGSCAN;
++					ic->ic_flags_ext &= ~(IEEE80211_FEXT_BGSCAN|IEEE80211_FEXT_BGSCAN_THR);
+ 				}
+ 			}
+ 			SCAN_PRIVATE(ss)->ss_iflags &= ~ISCAN_CANCEL;