From b41c2199127319c582b2762a4ea3bf628f283cd7 Mon Sep 17 00:00:00 2001
From: Mark Johnston <markj@FreeBSD.org>
Date: Thu, 7 Nov 2019 23:29:57 +0000
Subject: [PATCH] iwm: Avoid calling iwm_start() each time a descriptor is
 reclaimed.

Only perform the call when a qfull bit transitions.  While here, avoid
assignments in declarations in iwm_mvm_rx_tx_cmd().

MFC after:	2 weeks
Sponsored by:	The FreeBSD Foundation
---
 sys/dev/iwm/if_iwm.c | 31 +++++++++++++++++++------------
 1 file changed, 19 insertions(+), 12 deletions(-)

diff --git a/sys/dev/iwm/if_iwm.c b/sys/dev/iwm/if_iwm.c
index 99f0d578afc..aa743b894f4 100644
--- a/sys/dev/iwm/if_iwm.c
+++ b/sys/dev/iwm/if_iwm.c
@@ -3337,14 +3337,21 @@ iwm_mvm_rx_tx_cmd_single(struct iwm_softc *sc, struct iwm_rx_packet *pkt,
 static void
 iwm_mvm_rx_tx_cmd(struct iwm_softc *sc, struct iwm_rx_packet *pkt)
 {
-	struct iwm_cmd_header *cmd_hdr = &pkt->hdr;
-	int idx = cmd_hdr->idx;
-	int qid = cmd_hdr->qid;
-	struct iwm_tx_ring *ring = &sc->txq[qid];
-	struct iwm_tx_data *txd = &ring->data[idx];
-	struct iwm_node *in = txd->in;
-	struct mbuf *m = txd->m;
-	int status;
+	struct iwm_cmd_header *cmd_hdr;
+	struct iwm_tx_ring *ring;
+	struct iwm_tx_data *txd;
+	struct iwm_node *in;
+	struct mbuf *m;
+	int idx, qid, qmsk, status;
+
+	cmd_hdr = &pkt->hdr;
+	idx = cmd_hdr->idx;
+	qid = cmd_hdr->qid;
+
+	ring = &sc->txq[qid];
+	txd = &ring->data[idx];
+	in = txd->in;
+	m = txd->m;
 
 	KASSERT(txd->done == 0, ("txd not done"));
 	KASSERT(txd->in != NULL, ("txd without node"));
@@ -3366,11 +3373,11 @@ iwm_mvm_rx_tx_cmd(struct iwm_softc *sc, struct iwm_rx_packet *pkt)
 
 	ieee80211_tx_complete(&in->in_ni, m, status);
 
-	if (--ring->queued < IWM_TX_RING_LOMARK) {
-		sc->qfullmsk &= ~(1 << ring->qid);
-		if (sc->qfullmsk == 0) {
+	qmsk = 1 << qid;
+	if (--ring->queued < IWM_TX_RING_LOMARK && (sc->qfullmsk & qmsk) != 0) {
+		sc->qfullmsk &= ~qmsk;
+		if (sc->qfullmsk == 0)
 			iwm_start(sc);
-		}
 	}
 }