mt76: testmode: make tx queued limit adjustable

Originally, tx queued limit is set to 1000 to prevent from running out
of tx token. If a new testmode tx is triggered while the previous one
hasn't finished yet, we'll wait a period of time until tx_done equals to
tx_queued. Normally, current queued limit can finish in 10 seconds.

However, if ipg is configured to a larger value, less than 1000 packets
can be done in the default timeout period, which may lead to a crash
when a new testmode tx triggered.

To deal with this, make tx queued limit dynamically adjusted according
to ipg value.
Signed-off-by: Shayne Chen <shayne.chen@mediatek.com>
Signed-off-by: Felix Fietkau <nbd@nbd.name>

drivers/net/wireless/mediatek/mt76/mt76.h

@@ -552,6 +552,7 @@ struct mt76_testmode_data {
 
 	u32 tx_pending;
 	u32 tx_queued;
+	u16 tx_queued_limit;
 	u32 tx_done;
 	struct {
 		u64 packets[__MT_RXQ_MAX];

drivers/net/wireless/mediatek/mt76/testmode.c

@@ -30,6 +30,7 @@ void mt76_testmode_tx_pending(struct mt76_phy *phy)
 	struct mt76_wcid *wcid = &dev->global_wcid;
 	struct sk_buff *skb = td->tx_skb;
 	struct mt76_queue *q;
+	u16 tx_queued_limit;
 	int qid;
 
 	if (!skb || !td->tx_pending)
@@ -38,9 +39,12 @@ void mt76_testmode_tx_pending(struct mt76_phy *phy)
 	qid = skb_get_queue_mapping(skb);
 	q = phy->q_tx[qid];
 
+	tx_queued_limit = td->tx_queued_limit ? td->tx_queued_limit : 1000;
+
 	spin_lock_bh(&q->lock);
 
-	while (td->tx_pending > 0 && td->tx_queued - td->tx_done < 1000 &&
+	while (td->tx_pending > 0 &&
+	       td->tx_queued - td->tx_done < tx_queued_limit &&
 	       q->queued < q->ndesc / 2) {
 		int ret;
 
@@ -196,7 +200,8 @@ mt76_testmode_tx_stop(struct mt76_phy *phy)
 
 	mt76_worker_enable(&dev->tx_worker);
 
-	wait_event_timeout(dev->tx_wait, td->tx_done == td->tx_queued, 10 * HZ);
+	wait_event_timeout(dev->tx_wait, td->tx_done == td->tx_queued,
+			   MT76_TM_TIMEOUT * HZ);
 
 	dev_kfree_skb(td->tx_skb);
 	td->tx_skb = NULL;

drivers/net/wireless/mediatek/mt76/testmode.h

@@ -5,6 +5,8 @@
 #ifndef __MT76_TESTMODE_H
 #define __MT76_TESTMODE_H
 
+#define MT76_TM_TIMEOUT	10
+
 /**
  * enum mt76_testmode_attr - testmode attributes inside NL80211_ATTR_TESTDATA
  *