linux-kernel - [PATCH 3.14 025/228] iwlwifi: mvm: rs: reinit rs if no tx for a long time

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Date:	Wed,  4 Jun 2014 16:20:54 -0700
From:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:	linux-kernel@...r.kernel.org
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	stable@...r.kernel.org, Eyal Shapira <eyalx.shapira@...el.com>,
	Emmanuel Grumbach <emmanuel.grumbach@...el.com>
Subject: [PATCH 3.14 025/228] iwlwifi: mvm: rs: reinit rs if no tx for a long time

3.14-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Eyal Shapira <eyal@...ery.com>

commit 87d5e4155c0088e6766b4f0193b63fa0eab71220 upstream.

After being idle for a long time (>5sec) the rs statistics
will be stale so we prefer to reset rs and start from legacy
rates again. This gives better results when the attenuation
increased signficantly (e.g. we got further from the AP) and
after a while we start Tx
Note that the first Tx after the idle period will still go out
in the old modulation and rate but this seemed a simpler approach
compared to adding a timer or modifying mac80211 for this.
The negative impact is negligble as we'll recover quickly.

Signed-off-by: Eyal Shapira <eyalx.shapira@...el.com>
Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@...el.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/net/wireless/iwlwifi/mvm/rs.c |   22 +++++++++++++++++++++-
 drivers/net/wireless/iwlwifi/mvm/rs.h |    1 +
 2 files changed, 22 insertions(+), 1 deletion(-)

--- a/drivers/net/wireless/iwlwifi/mvm/rs.c
+++ b/drivers/net/wireless/iwlwifi/mvm/rs.c
@@ -59,7 +59,7 @@
 /* max allowed rate miss before sync LQ cmd */
 #define IWL_MISSED_RATE_MAX		15
 #define RS_STAY_IN_COLUMN_TIMEOUT       (5*HZ)
-
+#define RS_IDLE_TIMEOUT                 (5*HZ)
 
 static u8 rs_ht_to_legacy[] = {
 	[IWL_RATE_MCS_0_INDEX] = IWL_RATE_6M_INDEX,
@@ -991,6 +991,13 @@ static void rs_tx_status(void *mvm_r, st
 		return;
 	}
 
+#ifdef CPTCFG_MAC80211_DEBUGFS
+	/* Disable last tx check if we are debugging with fixed rate */
+	if (lq_sta->dbg_fixed_rate) {
+		IWL_DEBUG_RATE(mvm, "Fixed rate. avoid rate scaling\n");
+		return;
+	}
+#endif
 	if (!ieee80211_is_data(hdr->frame_control) ||
 	    info->flags & IEEE80211_TX_CTL_NO_ACK)
 		return;
@@ -1033,6 +1040,18 @@ static void rs_tx_status(void *mvm_r, st
 			mac_index++;
 	}
 
+	if (time_after(jiffies,
+		       (unsigned long)(lq_sta->last_tx + RS_IDLE_TIMEOUT))) {
+		int tid;
+		IWL_DEBUG_RATE(mvm, "Tx idle for too long. reinit rs\n");
+		for (tid = 0; tid < IWL_MAX_TID_COUNT; tid++)
+			ieee80211_stop_tx_ba_session(sta, tid);
+
+		iwl_mvm_rs_rate_init(mvm, sta, sband->band, false);
+		return;
+	}
+	lq_sta->last_tx = jiffies;
+
 	/* Here we actually compare this rate to the latest LQ command */
 	if ((mac_index < 0) ||
 	    (rate.sgi != !!(mac_flags & IEEE80211_TX_RC_SHORT_GI)) ||
@@ -2286,6 +2305,7 @@ void iwl_mvm_rs_rate_init(struct iwl_mvm
 			rs_rate_scale_clear_window(&lq_sta->lq_info[j].win[i]);
 
 	lq_sta->flush_timer = 0;
+	lq_sta->last_tx = jiffies;
 
 	IWL_DEBUG_RATE(mvm,
 		       "LQ: *** rate scale station global init for station %d ***\n",
--- a/drivers/net/wireless/iwlwifi/mvm/rs.h
+++ b/drivers/net/wireless/iwlwifi/mvm/rs.h
@@ -311,6 +311,7 @@ struct iwl_lq_sta {
 	u32 visited_columns;    /* Bitmask marking which Tx columns were
 				 * explored during a search cycle
 				 */
+	u64 last_tx;
 	bool is_vht;
 	enum ieee80211_band band;
 


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