iwlagn: add power_save module parameter

Add power_save module parameter to enable power management if needed
Default power management is disabled.
Signed-off-by: Wey-Yi Guy <wey-yi.w.guy@intel.com>

drivers/net/wireless/iwlwifi/iwl-agn.c

@@ -2545,11 +2545,10 @@ static int iwl_mac_setup_register(struct iwl_priv *priv,
 			    WIPHY_FLAG_DISABLE_BEACON_HINTS |
 			    WIPHY_FLAG_IBSS_RSN;
 
-	/*
-	 * For now, disable PS by default because it affects
-	 * RX performance significantly.
-	 */
-	hw->wiphy->flags &= ~WIPHY_FLAG_PS_ON_BY_DEFAULT;
+	if (iwlagn_mod_params.power_save)
+		hw->wiphy->flags |= WIPHY_FLAG_PS_ON_BY_DEFAULT;
+	else
+		hw->wiphy->flags &= ~WIPHY_FLAG_PS_ON_BY_DEFAULT;
 
 	hw->wiphy->max_scan_ssids = PROBE_OPTION_MAX;
 	/* we create the 802.11 header and a zero-length SSID element */
@@ -3827,6 +3826,11 @@ module_param_named(led_mode, iwlagn_mod_params.led_mode, int, S_IRUGO);
 MODULE_PARM_DESC(led_mode, "0=system default, "
 		"1=On(RF On)/Off(RF Off), 2=blinking (default: 0)");
 
+module_param_named(power_save, iwlagn_mod_params.power_save,
+		bool, S_IRUGO);
+MODULE_PARM_DESC(power_save,
+		 "enable WiFi power management (default: disable)");
+
 /*
  * For now, keep using power level 1 instead of automatically
  * adjusting ...

drivers/net/wireless/iwlwifi/iwl-core.h

@@ -163,6 +163,7 @@ struct iwl_mod_params {
 	bool bt_coex_active;	/* def: true = enable bt coex */
 	int led_mode;		/* def: 0 = system default */
 	bool no_sleep_autoadjust; /* def: true = disable autoadjust */
+	bool power_save;	/* def: false = disable power save */
 };
 
 /*