rt2x00: do not increment sequence number while re-transmitting

Currently rt2x00 devices retransmit the management frames with
incremented sequence number if hardware is assigning the sequence.

This is HW bug fixed already for non-QOS data frames, but it should
be fixed for management frames except beacon.

Without fix retransmitted frames have wrong SN:

 AlphaNet_e8:fb:36 Vivotek_52:31:51 Authentication, SN=1648, FN=0, Flags=........C Frame is not being retransmitted 1648 1
 AlphaNet_e8:fb:36 Vivotek_52:31:51 Authentication, SN=1649, FN=0, Flags=....R...C Frame is being retransmitted 1649 1
 AlphaNet_e8:fb:36 Vivotek_52:31:51 Authentication, SN=1650, FN=0, Flags=....R...C Frame is being retransmitted 1650 1

With the fix SN stays correctly the same:

 88:6a:e3:e8:f9:a2 8c:f5:a3:88:76:87 Authentication, SN=1450, FN=0, Flags=........C
 88:6a:e3:e8:f9:a2 8c:f5:a3:88:76:87 Authentication, SN=1450, FN=0, Flags=....R...C
 88:6a:e3:e8:f9:a2 8c:f5:a3:88:76:87 Authentication, SN=1450, FN=0, Flags=....R...C

Cc: stable@vger.kernel.org
Signed-off-by: Vijayakumar Durai <vijayakumar.durai1@vivint.com>
[sgruszka: simplify code, change comments and changelog]
Signed-off-by: Stanislaw Gruszka <sgruszka@redhat.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>

drivers/net/wireless/ralink/rt2x00/rt2x00.h

@@ -673,7 +673,6 @@ enum rt2x00_state_flags {
 	CONFIG_CHANNEL_HT40,
 	CONFIG_POWERSAVING,
 	CONFIG_HT_DISABLED,
-	CONFIG_QOS_DISABLED,
 	CONFIG_MONITORING,
 
 	/*

drivers/net/wireless/ralink/rt2x00/rt2x00mac.c

@@ -642,18 +642,8 @@ void rt2x00mac_bss_info_changed(struct ieee80211_hw *hw,
 			rt2x00dev->intf_associated--;
 
 		rt2x00leds_led_assoc(rt2x00dev, !!rt2x00dev->intf_associated);
-
-		clear_bit(CONFIG_QOS_DISABLED, &rt2x00dev->flags);
 	}
 
-	/*
-	 * Check for access point which do not support 802.11e . We have to
-	 * generate data frames sequence number in S/W for such AP, because
-	 * of H/W bug.
-	 */
-	if (changes & BSS_CHANGED_QOS && !bss_conf->qos)
-		set_bit(CONFIG_QOS_DISABLED, &rt2x00dev->flags);
-
 	/*
 	 * When the erp information has changed, we should perform
 	 * additional configuration steps. For all other changes we are done.

drivers/net/wireless/ralink/rt2x00/rt2x00queue.c

@@ -201,15 +201,18 @@ static void rt2x00queue_create_tx_descriptor_seq(struct rt2x00_dev *rt2x00dev,
 	if (!rt2x00_has_cap_flag(rt2x00dev, REQUIRE_SW_SEQNO)) {
 		/*
 		 * rt2800 has a H/W (or F/W) bug, device incorrectly increase
-		 * seqno on retransmited data (non-QOS) frames. To workaround
-		 * the problem let's generate seqno in software if QOS is
-		 * disabled.
+		 * seqno on retransmitted data (non-QOS) and management frames.
+		 * To workaround the problem let's generate seqno in software.
+		 * Except for beacons which are transmitted periodically by H/W
+		 * hence hardware has to assign seqno for them.
 		 */
-		if (test_bit(CONFIG_QOS_DISABLED, &rt2x00dev->flags))
-			__clear_bit(ENTRY_TXD_GENERATE_SEQ, &txdesc->flags);
-		else
+	    	if (ieee80211_is_beacon(hdr->frame_control)) {
+			__set_bit(ENTRY_TXD_GENERATE_SEQ, &txdesc->flags);
 			/* H/W will generate sequence number */
 			return;
+		}
+
+		__clear_bit(ENTRY_TXD_GENERATE_SEQ, &txdesc->flags);
 	}
 
 	/*