ath9k: check old power mode before clearing cycle counters

ath9k_ps_wakeup() clears the cycle counters after waking up the
hardware using ath9k_hw_setpower, however if power save is disabled,
then the counters will contain useful data, which then gets discarded.
Fix this by checking the old power mode before discarding any data.
Signed-off-by: Felix Fietkau <nbd@openwrt.org>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/ath/ath9k/main.c

@@ -94,11 +94,13 @@ void ath9k_ps_wakeup(struct ath_softc *sc)
 {
 	struct ath_common *common = ath9k_hw_common(sc->sc_ah);
 	unsigned long flags;
+	enum ath9k_power_mode power_mode;
 
 	spin_lock_irqsave(&sc->sc_pm_lock, flags);
 	if (++sc->ps_usecount != 1)
 		goto unlock;
 
+	power_mode = sc->sc_ah->power_mode;
 	ath9k_hw_setpower(sc->sc_ah, ATH9K_PM_AWAKE);
 
 	/*
@@ -106,10 +108,12 @@ void ath9k_ps_wakeup(struct ath_softc *sc)
 	 * useful data. Better clear them now so that they don't mess up
 	 * survey data results.
 	 */
+	if (power_mode != ATH9K_PM_AWAKE) {
 		spin_lock(&common->cc_lock);
 		ath_hw_cycle_counters_update(common);
 		memset(&common->cc_survey, 0, sizeof(common->cc_survey));
 		spin_unlock(&common->cc_lock);
+	}
 
  unlock:
 	spin_unlock_irqrestore(&sc->sc_pm_lock, flags);