[Madwifi-devel] PATCH 1/2: lock the slottime for long-distance links

[Thorsten v. E. <tv...@vo...>]

Last night I finally upgraded two of my long distance nodes from a 9 
month old madwifi to the latest one. Lots of improvements and the sample 
rate control works a whole lot better! Thanks so much to everyone who 
spent time improving the driver!

Below is an updated copy of one of my old patches that is still 
relevant. It allows athctrl to lock the slottime when changing the 
acktimeout and ctstimeout. Currently the slottime (which should be about 
1/2 the acktimeout) is changed back to 9us or 20us when certain 
association events occur. If lockslottime (another sysctl variable) is 
set, then this change is prevented. This has worked well for me for the 
past 9 months.

I'm not convinced that the lockslottime variable is the nicest approach. 
The benefit is that it exposes what's going on. An alternative would be 
to implicitly lock the slottime if the acktimeout is not the standard value.

The patch below changes ath/if_ath.c and ath/if_athvar.h. I'm sending a 
2nd email with the patch to tools/athctrl.c

Cheers,
	Thorsten


--- ath-orig/if_ath.c	Wed Sep 21 23:18:07 2005
+++ ath/if_ath.c	Wed Sep 21 23:30:56 2005
@@ -2384,6 +2384,8 @@

  /*
   * Set the slot time based on the current setting.
+ * This is called by ath_updateslot below and when a non-ERP node
+ * joins the network.
   */
  static void
  ath_setslottime(struct ath_softc *sc)
@@ -2391,10 +2393,16 @@
  	struct ieee80211com *ic = &sc->sc_ic;
  	struct ath_hal *ah = sc->sc_ah;

-	if (ic->ic_flags & IEEE80211_F_SHSLOT)
-		ath_hal_setslottime(ah, HAL_SLOT_TIME_9);
-	else
-		ath_hal_setslottime(ah, HAL_SLOT_TIME_20);
+	/* If the user has asked to lock the slot-time, ignore the
+	 * slot time adjustment. This is useful in long-range networks
+	 * that require a slot time larger than the standard ones. -TvE
+	 */
+	if (!sc->sc_lockslottime) {
+		if (ic->ic_flags & IEEE80211_F_SHSLOT)
+			ath_hal_setslottime(ah, HAL_SLOT_TIME_9);
+		else
+			ath_hal_setslottime(ah, HAL_SLOT_TIME_20);
+	}
  	sc->sc_updateslot = OK;
  }

@@ -6211,6 +6219,7 @@
  	ATH_RAWDEV_TYPE = 19,
  	ATH_RXFILTER	= 20,
  	ATH_RADARSIM	= 21,
+	ATH_LOCKSLOTTIME= 22,
  };

  static int
@@ -6233,6 +6242,9 @@
  				if (!ath_hal_setslottime(ah, val))
  					ret = -EINVAL;
  				break;
+			case ATH_LOCKSLOTTIME:
+				sc->sc_lockslottime = val != 0;
+				break;
  			case ATH_ACKTIMEOUT:
  				if (!ath_hal_setacktimeout(ah, val))
  					ret = -EINVAL;
@@ -6341,6 +6353,9 @@
  		case ATH_SLOTTIME:
  			val = ath_hal_getslottime(ah);
  			break;
+		case ATH_LOCKSLOTTIME:
+			val = sc->sc_lockslottime;
+			break;
  		case ATH_ACKTIMEOUT:
  			val = ath_hal_getacktimeout(ah);
  			break;
@@ -6428,6 +6443,11 @@
  	  .mode		= 0644,
  	  .proc_handler	= ath_sysctl_halparam
  	},
+	{ .ctl_name	= ATH_LOCKSLOTTIME,
+	  .procname	= "lockslottime",
+	  .mode		= 0644,
+	  .proc_handler	= ath_sysctl_halparam
+	},
  	{ .ctl_name	= ATH_ACKTIMEOUT,
  	  .procname	= "acktimeout",
  	  .mode		= 0644,
@@ -6580,6 +6600,7 @@
  #endif
  	sc->sc_txantenna = 0;		/* default to auto-selection */
  	sc->sc_txintrperiod = ATH_TXINTR_PERIOD;
+	sc->sc_lockslottime = 0;
  }

  static void
--- ath-orig/if_athvar.h	Wed Sep 21 23:18:07 2005
+++ ath/if_athvar.h	Wed Sep 21 23:31:59 2005
@@ -264,6 +264,7 @@
  				sc_needmib : 1,	/* enable MIB stats intr */
  				sc_hasdiversity : 1,/* rx diversity available */
  				sc_diversity : 1,/* enable rx diversity */
+				sc_lockslottime : 1,/* lock slot time value */
  				sc_hasveol : 1,	/* tx VEOL support */
  				sc_hastpc  : 1,	/* per-packet TPC support */
  				sc_ledstate: 1,	/* LED on/off state */