mt76: reserve enough room for USB tx skbs

Reserve enough room for USB skb, so we don not need to check
the room every time we send frame.

Signed-off-by: Stanislaw Gruszka <sgruszka@redhat.com>
Signed-off-by: Felix Fietkau <nbd@nbd.name>

drivers/net/wireless/mediatek/mt76/mt76x0/init.c

@@ -368,7 +368,10 @@ int mt76x0_register_device(struct mt76x02_dev *dev)
 	hw->max_rates = 1;
 	hw->max_report_rates = 7;
 	hw->max_rate_tries = 1;
-	hw->extra_tx_headroom = sizeof(struct mt76x02_txwi) + 4 + 2;
+	hw->extra_tx_headroom = 2;
+	if (mt76_is_usb(dev))
+		hw->extra_tx_headroom += sizeof(struct mt76x02_txwi) +
+					 MT_DMA_HDR_LEN;
 
 	hw->sta_data_size = sizeof(struct mt76x02_sta);
 	hw->vif_data_size = sizeof(struct mt76x02_vif);

drivers/net/wireless/mediatek/mt76/mt76x02_usb_core.c

@@ -34,17 +34,6 @@ void mt76x02u_tx_complete_skb(struct mt76_dev *mdev, struct mt76_queue *q,
 }
 EXPORT_SYMBOL_GPL(mt76x02u_tx_complete_skb);
 
-static int mt76x02u_check_skb_rooms(struct sk_buff *skb)
-{
-	int hdr_len = ieee80211_get_hdrlen_from_skb(skb);
-	u32 need_head;
-
-	need_head = sizeof(struct mt76x02_txwi) + MT_DMA_HDR_LEN;
-	if (hdr_len % 4)
-		need_head += 2;
-	return skb_cow(skb, need_head);
-}
-
 int mt76x02u_skb_dma_info(struct sk_buff *skb, int port, u32 flags)
 {
 	struct sk_buff *iter, *last = skb;
@@ -106,11 +95,7 @@ int mt76x02u_tx_prepare_skb(struct mt76_dev *mdev, void *data,
 {
 	struct mt76x02_dev *dev = container_of(mdev, struct mt76x02_dev, mt76);
 	struct mt76x02_txwi *txwi;
-	int err, len = skb->len;
-
-	err = mt76x02u_check_skb_rooms(skb);
-	if (err < 0)
-		return -ENOMEM;
+	int len = skb->len;
 
 	mt76x02_insert_hdr_pad(skb);
 

drivers/net/wireless/mediatek/mt76/mt76x2/init.c

@@ -167,6 +167,9 @@ void mt76x2_init_device(struct mt76x02_dev *dev)
 	hw->max_report_rates = 7;
 	hw->max_rate_tries = 1;
 	hw->extra_tx_headroom = 2;
+	if (mt76_is_usb(dev))
+		hw->extra_tx_headroom += sizeof(struct mt76x02_txwi) +
+					 MT_DMA_HDR_LEN;
 
 	hw->sta_data_size = sizeof(struct mt76x02_sta);
 	hw->vif_data_size = sizeof(struct mt76x02_vif);