ath9k: Fix a DMA latency issue for Intel Pinetrail platforms.

Throughput was severely affected in Intel Pinetrail platforms
because of a DMA problem in C3 state. This patch fixes this
issue.

Signed-off-by: Vivek Natarajan <vnatarajan@atheros.com>
CC: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/ath/ath9k/ath9k.h

@@ -675,6 +675,7 @@ static inline void ath_read_cachesize(struct ath_common *common, int *csz)
 }
 
 extern struct ieee80211_ops ath9k_ops;
+extern struct pm_qos_request_list ath9k_pm_qos_req;
 extern int modparam_nohwcrypt;
 extern int led_blink;
 

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

@@ -15,6 +15,7 @@
  */
 
 #include <linux/slab.h>
+#include <linux/pm_qos_params.h>
 
 #include "ath9k.h"
 
@@ -179,6 +180,8 @@ static const struct ath_ops ath9k_common_ops = {
 	.write = ath9k_iowrite32,
 };
 
+struct pm_qos_request_list ath9k_pm_qos_req;
+
 /**************************/
 /*     Initialization     */
 /**************************/
@@ -756,6 +759,9 @@ int ath9k_init_device(u16 devid, struct ath_softc *sc, u16 subsysid,
 	ath_init_leds(sc);
 	ath_start_rfkill_poll(sc);
 
+	pm_qos_add_request(&ath9k_pm_qos_req, PM_QOS_CPU_DMA_LATENCY,
+			   PM_QOS_DEFAULT_VALUE);
+
 	return 0;
 
 error_world:
@@ -811,6 +817,8 @@ void ath9k_deinit_device(struct ath_softc *sc)
 
 	ath9k_ps_wakeup(sc);
 
+	pm_qos_remove_request(&ath9k_pm_qos_req);
+
 	wiphy_rfkill_stop_polling(sc->hw->wiphy);
 	ath_deinit_leds(sc);
 

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

@@ -15,6 +15,7 @@
  */
 
 #include <linux/nl80211.h>
+#include <linux/pm_qos_params.h>
 #include "ath9k.h"
 #include "btcoex.h"
 
@@ -1239,6 +1240,8 @@ static int ath9k_start(struct ieee80211_hw *hw)
 			ath9k_btcoex_timer_resume(sc);
 	}
 
+	pm_qos_update_request(&ath9k_pm_qos_req, 55);
+
 mutex_unlock:
 	mutex_unlock(&sc->mutex);
 
@@ -1416,6 +1419,8 @@ static void ath9k_stop(struct ieee80211_hw *hw)
 
 	sc->sc_flags |= SC_OP_INVALID;
 
+	pm_qos_update_request(&ath9k_pm_qos_req, PM_QOS_DEFAULT_VALUE);
+
 	mutex_unlock(&sc->mutex);
 
 	ath_print(common, ATH_DBG_CONFIG, "Driver halt\n");