wl12xx: avoid premature elp entrance

The elp_work is being enqueued on wl1271_ps_elp_sleep, but doesn't get
cancelled on wl1271_ps_elp_wakeup. This might cause immediate entrance
to elp when the wl->mutex is being released, rather than using the delayed
enqueueing optimization.

Cancel elp_work on wakeup request, and add a new WL1271_FLAG_ELP_REQUESTED
flag to further synchronize the elp actions.

[Fixed a couple of typos in some comments -- Luca]
Signed-off-by: Eliad Peller <eliad@wizery.com>
Signed-off-by: Luciano Coelho <coelho@ti.com>

drivers/net/wireless/wl12xx/ps.c

@@ -43,6 +43,10 @@ void wl1271_elp_work(struct work_struct *work)
 	if (unlikely(wl->state == WL1271_STATE_OFF))
 		goto out;
 
+	/* our work might have been already cancelled */
+	if (unlikely(!test_bit(WL1271_FLAG_ELP_REQUESTED, &wl->flags)))
+		goto out;
+
 	if (test_bit(WL1271_FLAG_IN_ELP, &wl->flags) ||
 	    (!test_bit(WL1271_FLAG_PSM, &wl->flags) &&
 	     !test_bit(WL1271_FLAG_IDLE, &wl->flags)))
@@ -61,12 +65,16 @@ void wl1271_elp_work(struct work_struct *work)
 /* Routines to toggle sleep mode while in ELP */
 void wl1271_ps_elp_sleep(struct wl1271 *wl)
 {
-	if (test_bit(WL1271_FLAG_PSM, &wl->flags) ||
-	    test_bit(WL1271_FLAG_IDLE, &wl->flags)) {
-		cancel_delayed_work(&wl->elp_work);
-		ieee80211_queue_delayed_work(wl->hw, &wl->elp_work,
-					     msecs_to_jiffies(ELP_ENTRY_DELAY));
-	}
+	/* we shouldn't get consecutive sleep requests */
+	if (WARN_ON(test_and_set_bit(WL1271_FLAG_ELP_REQUESTED, &wl->flags)))
+		return;
+
+	if (!test_bit(WL1271_FLAG_PSM, &wl->flags) &&
+	    !test_bit(WL1271_FLAG_IDLE, &wl->flags))
+		return;
+
+	ieee80211_queue_delayed_work(wl->hw, &wl->elp_work,
+				     msecs_to_jiffies(ELP_ENTRY_DELAY));
 }
 
 int wl1271_ps_elp_wakeup(struct wl1271 *wl)
@@ -77,6 +85,16 @@ int wl1271_ps_elp_wakeup(struct wl1271 *wl)
 	u32 start_time = jiffies;
 	bool pending = false;
 
+	/*
+	 * we might try to wake up even if we didn't go to sleep
+	 * before (e.g. on boot)
+	 */
+	if (!test_and_clear_bit(WL1271_FLAG_ELP_REQUESTED, &wl->flags))
+		return 0;
+
+	/* don't cancel_sync as it might contend for a mutex and deadlock */
+	cancel_delayed_work(&wl->elp_work);
+
 	if (!test_bit(WL1271_FLAG_IN_ELP, &wl->flags))
 		return 0;
 

drivers/net/wireless/wl12xx/wl12xx.h

@@ -345,6 +345,7 @@ enum wl12xx_flags {
 	WL1271_FLAG_TX_QUEUE_STOPPED,
 	WL1271_FLAG_TX_PENDING,
 	WL1271_FLAG_IN_ELP,
+	WL1271_FLAG_ELP_REQUESTED,
 	WL1271_FLAG_PSM,
 	WL1271_FLAG_PSM_REQUESTED,
 	WL1271_FLAG_IRQ_RUNNING,