mt7601u: wait for clear rxq when stopping mac

mt7601u_mac_stop_hw should stop polling the rxq once it remains empty
but instead continues polling after the rxq status stays clear; bringing
down the interface takes about six seconds from this alone.

Speed up path by exiting rxq loop once status repeatedly polls empty.

Signed-off-by: Anthony Romano <anthony.romano@coreos.com>
Reviewed-by: Jakub Kicinski <kubakici@wp.pl>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>

drivers/net/wireless/mediatek/mt7601u/init.c

@@ -293,13 +293,13 @@ static void mt7601u_mac_stop_hw(struct mt7601u_dev *dev)
 	ok = 0;
 	i = 200;
 	while (i--) {
-		if ((mt76_rr(dev, 0x0430) & 0x00ff0000) ||
-		    (mt76_rr(dev, 0x0a30) & 0xffffffff) ||
-		    (mt76_rr(dev, 0x0a34) & 0xffffffff))
-			ok++;
-		if (ok > 6)
-			break;
-
+		if (!(mt76_rr(dev, MT_RXQ_STA) & 0x00ff0000) &&
+		    !mt76_rr(dev, 0x0a30) &&
+		    !mt76_rr(dev, 0x0a34)) {
+			if (ok++ > 5)
+				break;
+			continue;
+		}
 		msleep(1);
 	}
 

drivers/net/wireless/mediatek/mt7601u/regs.h

@@ -192,6 +192,9 @@
 #define MT_BCN_OFFSET_BASE		0x041c
 #define MT_BCN_OFFSET(_n)		(MT_BCN_OFFSET_BASE + ((_n) << 2))
 
+#define MT_RXQ_STA			0x0430
+#define MT_TXQ_STA			0x0434
+
 #define	MT_RF_CSR_CFG			0x0500
 #define MT_RF_CSR_CFG_DATA		GENMASK(7, 0)
 #define MT_RF_CSR_CFG_REG_ID		GENMASK(13, 8)