wl12xx: Avoid redundant TX work

TX might be handled in the threaded IRQ handler, in which case, TX work
might be scheduled just to discover it has nothing to do.

Save a few context switches by cancelling redundant TX work in case TX
is about to be handled in the threaded IRQ handler. Also, avoid
scheduling TX work from wl1271_op_tx if not needed.

Signed-off-by: Ido Yariv <ido@wizery.com>
Reviewed-by: Luciano Coelho <coelho@ti.com>
Signed-off-by: Luciano Coelho <coelho@ti.com>

2 files changed, 28 insertions, 5 deletions

diff --git a/drivers/net/wireless/wl12xx/main.c b/drivers/net/wireless/wl12xx/main.c
index f408c5a84cc9..2679abcf5a05 100644
--- a/drivers/net/wireless/wl12xx/main.c
+++ b/drivers/net/wireless/wl12xx/main.c
@@ -668,6 +668,11 @@ irqreturn_t wl1271_irq(int irq, void *cookie)
         struct wl1271 *wl = (struct wl1271 *)cookie;
         bool done = false;
         unsigned int defer_count;
+        unsigned long flags;
+
+        /* TX might be handled here, avoid redundant work */
+        set_bit(WL1271_FLAG_TX_PENDING, &wl->flags);
+        cancel_work_sync(&wl->tx_work);
 
         mutex_lock(&wl->mutex);
 
@@ -712,13 +717,17 @@ irqreturn_t wl1271_irq(int irq, void *cookie)
                         wl1271_rx(wl, &wl->fw_status->common);
 
                         /* Check if any tx blocks were freed */
+                        spin_lock_irqsave(&wl->wl_lock, flags);
                         if (!test_bit(WL1271_FLAG_FW_TX_BUSY, &wl->flags) &&
                             wl->tx_queue_count) {
+                                spin_unlock_irqrestore(&wl->wl_lock, flags);
                                 /*
                                  * In order to avoid starvation of the TX path,
                                  * call the work function directly.
                                  */
                                 wl1271_tx_work_locked(wl);
+                        } else {
+                                spin_unlock_irqrestore(&wl->wl_lock, flags);
                         }
 
                         /* check for tx results */
@@ -754,6 +763,14 @@ irqreturn_t wl1271_irq(int irq, void *cookie)
         wl1271_ps_elp_sleep(wl);
 
 out:
+        spin_lock_irqsave(&wl->wl_lock, flags);
+        /* In case TX was not handled here, queue TX work */
+        clear_bit(WL1271_FLAG_TX_PENDING, &wl->flags);
+        if (!test_bit(WL1271_FLAG_FW_TX_BUSY, &wl->flags) &&
+            wl->tx_queue_count)
+                ieee80211_queue_work(wl->hw, &wl->tx_work);
+        spin_unlock_irqrestore(&wl->wl_lock, flags);
+
         mutex_unlock(&wl->mutex);
 
         return IRQ_HANDLED;
@@ -1068,7 +1085,13 @@ static void wl1271_op_tx(struct ieee80211_hw *hw, struct sk_buff *skb)
         int q;
         u8 hlid = 0;
 
+        q = wl1271_tx_get_queue(skb_get_queue_mapping(skb));
+
+        if (wl->bss_type == BSS_TYPE_AP_BSS)
+                hlid = wl1271_tx_get_hlid(skb);
+
         spin_lock_irqsave(&wl->wl_lock, flags);
+
         wl->tx_queue_count++;
 
         /*
@@ -1081,12 +1104,8 @@ static void wl1271_op_tx(struct ieee80211_hw *hw, struct sk_buff *skb)
                 set_bit(WL1271_FLAG_TX_QUEUE_STOPPED, &wl->flags);
         }
 
-        spin_unlock_irqrestore(&wl->wl_lock, flags);
-
         /* queue the packet */
-        q = wl1271_tx_get_queue(skb_get_queue_mapping(skb));
         if (wl->bss_type == BSS_TYPE_AP_BSS) {
-                hlid = wl1271_tx_get_hlid(skb);
                 wl1271_debug(DEBUG_TX, "queue skb hlid %d q %d", hlid, q);
                 skb_queue_tail(&wl->links[hlid].tx_queue[q], skb);
         } else {
@@ -1098,8 +1117,11 @@ static void wl1271_op_tx(struct ieee80211_hw *hw, struct sk_buff *skb)
          * before that, the tx_work will not be initialized!
          */
 
-        if (!test_bit(WL1271_FLAG_FW_TX_BUSY, &wl->flags))
+        if (!test_bit(WL1271_FLAG_FW_TX_BUSY, &wl->flags) &&
+            !test_bit(WL1271_FLAG_TX_PENDING, &wl->flags))
                 ieee80211_queue_work(wl->hw, &wl->tx_work);
+
+        spin_unlock_irqrestore(&wl->wl_lock, flags);
 }
 
 static struct notifier_block wl1271_dev_notifier = {
diff --git a/drivers/net/wireless/wl12xx/wl12xx.h b/drivers/net/wireless/wl12xx/wl12xx.h
index e395c0c4ebbd..86be83e25ec5 100644
--- a/drivers/net/wireless/wl12xx/wl12xx.h
+++ b/drivers/net/wireless/wl12xx/wl12xx.h
@@ -317,6 +317,7 @@ enum wl12xx_flags {
         WL1271_FLAG_JOINED,
         WL1271_FLAG_GPIO_POWER,
         WL1271_FLAG_TX_QUEUE_STOPPED,
+        WL1271_FLAG_TX_PENDING,
         WL1271_FLAG_IN_ELP,
         WL1271_FLAG_PSM,
         WL1271_FLAG_PSM_REQUESTED,