ath9k: remove pointless sc_txintrperiod and spin_lock_bh on tx prepare

sc_txintrperiod is currently set to 0 and never updated. We won't
be using this, if anything we will consider using TX interrupt
mitigation but that is different and not yet tested. So remove
sc_txintrperiod and the pointless spin_lock_bh() on tx prepare.

Signed-off-by: Luis R. Rodriguez <lrodriguez@atheros.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

3 files changed, 15 insertions, 29 deletions

diff --git a/drivers/net/wireless/ath9k/ath9k.h b/drivers/net/wireless/ath9k/ath9k.h
index accace5f7efb..a6063dea0fa2 100644
--- a/drivers/net/wireless/ath9k/ath9k.h
+++ b/drivers/net/wireless/ath9k/ath9k.h
@@ -138,6 +138,19 @@ struct ath_desc {
 #define ATH9K_TXDESC_NOACK              0x0002
 #define ATH9K_TXDESC_RTSENA             0x0004
 #define ATH9K_TXDESC_CTSENA             0x0008
+/* ATH9K_TXDESC_INTREQ forces a tx interrupt to be generated for
+ * the descriptor its marked on.  We take a tx interrupt to reap
+ * descriptors when the h/w hits an EOL condition or
+ * when the descriptor is specifically marked to generate
+ * an interrupt with this flag. Descriptors should be
+ * marked periodically to insure timely replenishing of the
+ * supply needed for sending frames. Defering interrupts
+ * reduces system load and potentially allows more concurrent
+ * work to be done but if done to aggressively can cause
+ * senders to backup. When the hardware queue is left too
+ * large rate control information may also be too out of
+ * date. An Alternative for this is TX interrupt mitigation
+ * but this needs more testing. */
 #define ATH9K_TXDESC_INTREQ             0x0010
 #define ATH9K_TXDESC_VEOL               0x0020
 #define ATH9K_TXDESC_EXT_ONLY           0x0040
diff --git a/drivers/net/wireless/ath9k/core.h b/drivers/net/wireless/ath9k/core.h
index 59d835b72cd8..fbff9aa4c28f 100644
--- a/drivers/net/wireless/ath9k/core.h
+++ b/drivers/net/wireless/ath9k/core.h
@@ -443,9 +443,6 @@ struct ath_txq {
         u8 axq_aggr_depth;              /* aggregates queued */
         u32 axq_totalqueued;            /* total ever queued */
 
-        /* count to determine if descriptor should generate int on this txq. */
-        u32 axq_intrcnt;
-
         bool stopped;                   /* Is mac80211 queue stopped ? */
         struct ath_buf *axq_linkbuf;    /* virtual addr of last buffer*/
 
@@ -1007,7 +1004,6 @@ struct ath_softc {
         struct ath_txq sc_txq[ATH9K_NUM_TX_QUEUES];
         struct ath_descdma sc_txdma;
         u32 sc_txqsetup;
-        u32 sc_txintrperiod;    /* tx interrupt batching */
         int sc_haltype2q[ATH9K_WME_AC_VO+1]; /* HAL WME AC -> h/w qnum */
         u16 seq_no; /* TX sequence number */
 
diff --git a/drivers/net/wireless/ath9k/xmit.c b/drivers/net/wireless/ath9k/xmit.c
index 9fa395418a6c..8073c71b3a67 100644
--- a/drivers/net/wireless/ath9k/xmit.c
+++ b/drivers/net/wireless/ath9k/xmit.c
@@ -286,7 +286,8 @@ static int ath_tx_prepare(struct ath_softc *sc,
 
         /* Fill flags */
 
-        txctl->flags |= ATH9K_TXDESC_CLRDMASK; /* needed for crypto errors */
+        txctl->flags |= ATH9K_TXDESC_CLRDMASK /* needed for crypto errors */
+                | ATH9K_TXDESC_INTREQ; /* Generate an interrupt */
 
         if (tx_info->flags & IEEE80211_TX_CTL_NO_ACK)
                 txctl->flags |= ATH9K_TXDESC_NOACK;
@@ -363,28 +364,6 @@ static int ath_tx_prepare(struct ath_softc *sc,
                 rcs[0].tries = ATH_TXMAXTRY;
         }
 
-        /*
-         * Determine if a tx interrupt should be generated for
-         * this descriptor.  We take a tx interrupt to reap
-         * descriptors when the h/w hits an EOL condition or
-         * when the descriptor is specifically marked to generate
-         * an interrupt.  We periodically mark descriptors in this
-         * way to insure timely replenishing of the supply needed
-         * for sending frames.  Defering interrupts reduces system
-         * load and potentially allows more concurrent work to be
-         * done but if done to aggressively can cause senders to
-         * backup.
-         *
-         * NB: use >= to deal with sc_txintrperiod changing
-         *     dynamically through sysctl.
-         */
-        spin_lock_bh(&txq->axq_lock);
-        if ((++txq->axq_intrcnt >= sc->sc_txintrperiod)) {
-                txctl->flags |= ATH9K_TXDESC_INTREQ;
-                txq->axq_intrcnt = 0;
-        }
-        spin_unlock_bh(&txq->axq_lock);
-
         if (is_multicast_ether_addr(hdr->addr1)) {
                 antenna = sc->sc_mcastantenna + 1;
                 sc->sc_mcastantenna = (sc->sc_mcastantenna + 1) & 0x1;
@@ -1166,7 +1145,6 @@ static int ath_tx_processq(struct ath_softc *sc, struct ath_txq *txq)
         nacked = 0;
         for (;;) {
                 spin_lock_bh(&txq->axq_lock);
-                txq->axq_intrcnt = 0; /* reset periodic desc intr count */
                 if (list_empty(&txq->axq_q)) {
                         txq->axq_link = NULL;
                         txq->axq_linkbuf = NULL;
@@ -2164,7 +2142,6 @@ struct ath_txq *ath_txq_setup(struct ath_softc *sc, int qtype, int subtype)
                 txq->axq_depth = 0;
                 txq->axq_aggr_depth = 0;
                 txq->axq_totalqueued = 0;
-                txq->axq_intrcnt = 0;
                 txq->axq_linkbuf = NULL;
                 sc->sc_txqsetup |= 1<<qnum;
         }