[PATCH] ath9k: Handle txpower changes even when TPC is disabled

[Remi Pommarel <repk@triplefau.lt>]

When TPC is disabled IEEE80211_CONF_CHANGE_POWER event can be handled to
reconfigure HW's maximum txpower.

This fixes 0dBm txpower setting when user attaches to an interface for
the first time with the following scenario:

ieee80211_do_open()
    ath9k_add_interface()
        ath9k_set_txpower() /* Set TX power with not yet initialized
                               sc->hw->conf.power_level */

    ieee80211_hw_config() /* Iniatilize sc->hw->conf.power_level and
                             raise IEEE80211_CONF_CHANGE_POWER */

    ath9k_config() /* IEEE80211_CONF_CHANGE_POWER is ignored */

This issue can be reproduced with the following:

  $ modprobe -r ath9k
  $ modprobe ath9k
  $ wpa_supplicant -i wlan0 -c /tmp/wpa.conf &
  $ iw dev /* Here TX power is either 0 or 3 depending on RF chain */
  $ killall wpa_supplicant
  $ iw dev /* TX power goes back to calibrated value and subsequent
              calls will be fine */

Fixes: 283dd11994cde ("ath9k: add per-vif TX power capability")
Cc: stable@vger.kernel.org
Signed-off-by: Remi Pommarel <repk@triplefau.lt>
---
 drivers/net/wireless/ath/ath9k/main.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/net/wireless/ath/ath9k/main.c b/drivers/net/wireless/ath/ath9k/main.c
index 0548aa3702e3..ef2b856670e1 100644
--- a/drivers/net/wireless/ath/ath9k/main.c
+++ b/drivers/net/wireless/ath/ath9k/main.c
@@ -1457,6 +1457,9 @@ static int ath9k_config(struct ieee80211_hw *hw, u32 changed)
 		ath_chanctx_set_channel(sc, ctx, &hw->conf.chandef);
 	}
 
+	if (changed & IEEE80211_CONF_CHANGE_POWER)
+		ath9k_set_txpower(sc, NULL);
+
 	mutex_unlock(&sc->mutex);
 	ath9k_ps_restore(sc);
 
-- 
2.25.0