ath5k: reduce interrupt load caused by rx/tx interrupts

While the rx/tx tasklet is pending, new unnecessary interrupts may arrive.
Decrease the load by temporarily disabling the interrupts until the tasklet
has completed.

Signed-off-by: Felix Fietkau <nbd@openwrt.org>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

3 files changed, 59 insertions, 3 deletions

diff --git a/drivers/net/wireless/ath/ath5k/ath5k.h b/drivers/net/wireless/ath/ath5k/ath5k.h
index fcaf4ed84ca5..e303db7ee6f6 100644
--- a/drivers/net/wireless/ath/ath5k/ath5k.h
+++ b/drivers/net/wireless/ath/ath5k/ath5k.h
@@ -872,6 +872,19 @@ enum ath5k_int {
         AR5K_INT_QTRIG  =       0x40000000, /* Non common */
         AR5K_INT_GLOBAL =       0x80000000,
 
+        AR5K_INT_TX_ALL = AR5K_INT_TXOK
+                | AR5K_INT_TXDESC
+                | AR5K_INT_TXERR
+                | AR5K_INT_TXEOL
+                | AR5K_INT_TXURN,
+
+        AR5K_INT_RX_ALL = AR5K_INT_RXOK
+                | AR5K_INT_RXDESC
+                | AR5K_INT_RXERR
+                | AR5K_INT_RXNOFRM
+                | AR5K_INT_RXEOL
+                | AR5K_INT_RXORN,
+
         AR5K_INT_COMMON  = AR5K_INT_RXOK
                 | AR5K_INT_RXDESC
                 | AR5K_INT_RXERR
diff --git a/drivers/net/wireless/ath/ath5k/base.c b/drivers/net/wireless/ath/ath5k/base.c
index a799d04e0c8c..c7da00454397 100644
--- a/drivers/net/wireless/ath/ath5k/base.c
+++ b/drivers/net/wireless/ath/ath5k/base.c
@@ -1444,6 +1444,21 @@ ath5k_receive_frame_ok(struct ath5k_softc *sc, struct ath5k_rx_status *rs)
 }
 
 static void
+ath5k_set_current_imask(struct ath5k_softc *sc)
+{
+        enum ath5k_int imask = sc->imask;
+        unsigned long flags;
+
+        spin_lock_irqsave(&sc->irqlock, flags);
+        if (sc->rx_pending)
+                imask &= ~AR5K_INT_RX_ALL;
+        if (sc->tx_pending)
+                imask &= ~AR5K_INT_TX_ALL;
+        ath5k_hw_set_imr(sc->ah, imask);
+        spin_unlock_irqrestore(&sc->irqlock, flags);
+}
+
+static void
 ath5k_tasklet_rx(unsigned long data)
 {
         struct ath5k_rx_status rs = {};
@@ -1506,6 +1521,8 @@ next:
         } while (ath5k_rxbuf_setup(sc, bf) == 0);
 unlock:
         spin_unlock(&sc->rxbuflock);
+        sc->rx_pending = false;
+        ath5k_set_current_imask(sc);
 }
 
 
@@ -1693,6 +1710,9 @@ ath5k_tasklet_tx(unsigned long data)
         for (i=0; i < AR5K_NUM_TX_QUEUES; i++)
                 if (sc->txqs[i].setup && (sc->ah->ah_txq_isr & BIT(i)))
                         ath5k_tx_processq(sc, &sc->txqs[i]);
+
+        sc->tx_pending = false;
+        ath5k_set_current_imask(sc);
 }
 
 
@@ -2122,6 +2142,20 @@ ath5k_intr_calibration_poll(struct ath5k_hw *ah)
          * AR5K_REG_ENABLE_BITS(ah, AR5K_CR, AR5K_CR_SWI); */
 }
 
+static void
+ath5k_schedule_rx(struct ath5k_softc *sc)
+{
+        sc->rx_pending = true;
+        tasklet_schedule(&sc->rxtq);
+}
+
+static void
+ath5k_schedule_tx(struct ath5k_softc *sc)
+{
+        sc->tx_pending = true;
+        tasklet_schedule(&sc->txtq);
+}
+
 irqreturn_t
 ath5k_intr(int irq, void *dev_id)
 {
@@ -2164,7 +2198,7 @@ ath5k_intr(int irq, void *dev_id)
                                 ieee80211_queue_work(sc->hw, &sc->reset_work);
                         }
                         else
-                                tasklet_schedule(&sc->rxtq);
+                                ath5k_schedule_rx(sc);
                 } else {
                         if (status & AR5K_INT_SWBA) {
                                 tasklet_hi_schedule(&sc->beacontq);
@@ -2182,10 +2216,10 @@ ath5k_intr(int irq, void *dev_id)
                                 ath5k_hw_update_tx_triglevel(ah, true);
                         }
                         if (status & (AR5K_INT_RXOK | AR5K_INT_RXERR))
-                                tasklet_schedule(&sc->rxtq);
+                                ath5k_schedule_rx(sc);
                         if (status & (AR5K_INT_TXOK | AR5K_INT_TXDESC
                                         | AR5K_INT_TXERR | AR5K_INT_TXEOL))
-                                tasklet_schedule(&sc->txtq);
+                                ath5k_schedule_tx(sc);
                         if (status & AR5K_INT_BMISS) {
                                 /* TODO */
                         }
@@ -2204,6 +2238,9 @@ ath5k_intr(int irq, void *dev_id)
 
         } while (ath5k_hw_is_intr_pending(ah) && --counter > 0);
 
+        if (sc->rx_pending || sc->tx_pending)
+                ath5k_set_current_imask(sc);
+
         if (unlikely(!counter))
                 ATH5K_WARN(sc, "too many interrupts, giving up for now\n");
 
@@ -2575,6 +2612,8 @@ done:
 
 static void stop_tasklets(struct ath5k_softc *sc)
 {
+        sc->rx_pending = false;
+        sc->tx_pending = false;
         tasklet_kill(&sc->rxtq);
         tasklet_kill(&sc->txtq);
         tasklet_kill(&sc->calib);
diff --git a/drivers/net/wireless/ath/ath5k/base.h b/drivers/net/wireless/ath/ath5k/base.h
index 978f1f4ac2f3..4c4e36064a3b 100644
--- a/drivers/net/wireless/ath/ath5k/base.h
+++ b/drivers/net/wireless/ath/ath5k/base.h
@@ -207,6 +207,10 @@ struct ath5k_softc {
 
         enum ath5k_int          imask;          /* interrupt mask copy */
 
+        spinlock_t              irqlock;
+        bool                    rx_pending;     /* rx tasklet pending */
+        bool                    tx_pending;     /* tx tasklet pending */
+
         u8                      lladdr[ETH_ALEN];
         u8                      bssidmask[ETH_ALEN];