From 16767f8db3165fc618b579db05bcbf20efe3e917 Mon Sep 17 00:00:00 2001
From: Felix Fietkau <nbd@openwrt.org>
Date: Tue, 22 Apr 2008 23:35:27 +0000
Subject: [PATCH] madwifi: put an upper limit on the amount of sampling that
 minstrel should do when the link changes its status from very good to
 slightly bad. the previous version of the patch could have resulted in
 erratic rate control behavior when there was a lot of sampling backlog.

SVN-Revision: 10921
---
 .../patches/345-minstrel_sampling.patch       | 36 ++++++++++++-------
 1 file changed, 24 insertions(+), 12 deletions(-)

diff --git a/package/madwifi/patches/345-minstrel_sampling.patch b/package/madwifi/patches/345-minstrel_sampling.patch
index ea4c25f3ada..3be5a8fee3f 100644
--- a/package/madwifi/patches/345-minstrel_sampling.patch
+++ b/package/madwifi/patches/345-minstrel_sampling.patch
@@ -1,7 +1,7 @@
 Index: madwifi-trunk-r3314/ath/if_ath.c
 ===================================================================
---- madwifi-trunk-r3314.orig/ath/if_ath.c	2008-04-21 02:44:23.000000000 +0200
-+++ madwifi-trunk-r3314/ath/if_ath.c	2008-04-21 03:33:02.000000000 +0200
+--- madwifi-trunk-r3314.orig/ath/if_ath.c	2008-04-21 09:13:19.000000000 +0200
++++ madwifi-trunk-r3314/ath/if_ath.c	2008-04-23 01:15:49.000000000 +0200
 @@ -8095,6 +8095,7 @@
  		ath_hal_setupxtxdesc(sc->sc_ah, ds, mrr.rate1, mrr.retries1,
  				     mrr.rate2, mrr.retries2,
@@ -12,8 +12,8 @@ Index: madwifi-trunk-r3314/ath/if_ath.c
  #ifndef ATH_SUPERG_FF
 Index: madwifi-trunk-r3314/ath/if_athvar.h
 ===================================================================
---- madwifi-trunk-r3314.orig/ath/if_athvar.h	2008-04-21 00:50:13.000000000 +0200
-+++ madwifi-trunk-r3314/ath/if_athvar.h	2008-04-21 03:31:48.000000000 +0200
+--- madwifi-trunk-r3314.orig/ath/if_athvar.h	2008-04-21 09:13:19.000000000 +0200
++++ madwifi-trunk-r3314/ath/if_athvar.h	2008-04-23 01:15:49.000000000 +0200
 @@ -446,6 +446,7 @@
  	u_int16_t bf_flags;				/* tx descriptor flags */
  	u_int64_t bf_tsf;
@@ -24,18 +24,30 @@ Index: madwifi-trunk-r3314/ath/if_athvar.h
  	 *      multiple segments.
 Index: madwifi-trunk-r3314/ath_rate/minstrel/minstrel.c
 ===================================================================
---- madwifi-trunk-r3314.orig/ath_rate/minstrel/minstrel.c	2008-04-21 02:50:31.000000000 +0200
-+++ madwifi-trunk-r3314/ath_rate/minstrel/minstrel.c	2008-04-21 04:08:36.000000000 +0200
-@@ -336,7 +336,7 @@
+--- madwifi-trunk-r3314.orig/ath_rate/minstrel/minstrel.c	2008-04-21 09:13:19.000000000 +0200
++++ madwifi-trunk-r3314/ath_rate/minstrel/minstrel.c	2008-04-23 01:15:50.000000000 +0200
+@@ -333,15 +333,19 @@
+ 		if (sn->static_rate_ndx >= 0) {
+ 			    ndx = sn->static_rate_ndx;
+ 		} else {
++			int delta;
  			sn->packet_count++;
  			sn->random_n = (sn->a * sn->random_n) + sn->b;
  			offset = sn->random_n & 0xf;
 -			if ((((100 * sn->sample_count) / (sn->sample_count + sn->packet_count)) < ath_lookaround_rate) && (offset < 2)) {
-+			if ((((100 * sn->sample_count) / (sn->packet_count ?: 1)) < ath_lookaround_rate) && (offset < 2)) {
++			delta = (sn->packet_count * ath_lookaround_rate / 100) - sn->sample_count;
++			if ((delta > 0) && (offset < 2)) {
  				sn->sample_count++;
  				sn->is_sampling = 1;
  				if (sn->packet_count >= 10000) {
-@@ -398,11 +398,14 @@
+ 					sn->sample_count = 0;
+ 					sn->packet_count = 0;
++				} else if (delta > sn->num_rates * 2) {
++					sn->sample_count += ((delta - sn->num_rates * 2) * ath_lookaround_rate) / 100;
+ 				}
+ 
+ 				/* Don't look for slowest rate (i.e. slowest
+@@ -398,11 +402,14 @@
  		if (sn->num_rates <= 0)
  			return;
  
@@ -52,7 +64,7 @@ Index: madwifi-trunk-r3314/ath_rate/minstrel/minstrel.c
  				rc1 = sn->max_tp_rate;
  		} else {
  			rc1 = sn->max_tp_rate2;
-@@ -525,6 +528,9 @@
+@@ -525,6 +532,9 @@
  		if (tries <= tries1)
  			return;
  
@@ -64,8 +76,8 @@ Index: madwifi-trunk-r3314/ath_rate/minstrel/minstrel.c
  		tries = tries - tries1;
 Index: madwifi-trunk-r3314/net80211/ieee80211_rate.h
 ===================================================================
---- madwifi-trunk-r3314.orig/net80211/ieee80211_rate.h	2008-01-31 03:29:42.000000000 +0100
-+++ madwifi-trunk-r3314/net80211/ieee80211_rate.h	2008-04-21 03:30:25.000000000 +0200
+--- madwifi-trunk-r3314.orig/net80211/ieee80211_rate.h	2008-04-21 09:11:19.000000000 +0200
++++ madwifi-trunk-r3314/net80211/ieee80211_rate.h	2008-04-21 09:13:19.000000000 +0200
 @@ -87,6 +87,7 @@
  	int retries2;
  	int rate3;
-- 
2.30.2