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mt76: add support for reporting tx status with skb

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MT76x2/MT76x0 has somewhat unreliable tx status reporting, and for that
reason the driver currently does not report per-skb tx ack status at all.
This breaks things like client idle polling, which relies on the tx ack
status of a transmitted nullfunc frame.

This patch adds code to report skb-attached tx status if requested by
mac80211 or the rate control module. Since tx status is polled from a
simple FIFO register, the code needs to account for the possibility of
tx status events getting lost.

The code keeps a list of skbs for which tx status is required and passes
them to mac80211 once tx status has been filled in and the DMA queue is
done with it.
If a tx status event is not received after one second, the status rates
are cleared, and a succesful ACK is indicated to avoid spurious disassoc
during assoc or client polling.

Signed-off-by: Felix Fietkau <nbd@nbd.name>
This commit is contained in:
Felix Fietkau 2018-10-25 16:11:34 +02:00
parent 59b55d066f
commit 88046b2c9f
11 changed files with 231 additions and 95 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
drivers/net/wireless/mediatek/mt76/dma.c
View File

@ -258,6 +258,7 @@ int mt76_dma_tx_queue_skb(struct mt76_dev *dev, struct mt76_queue *q,
return -ENOMEM;
}
skb->prev = skb->next = NULL;
dma_sync_single_for_cpu(dev->dev, t->dma_addr, sizeof(t->txwi),
DMA_TO_DEVICE);
ret = dev->drv->tx_prepare_skb(dev, &t->txwi, skb, q, wcid, sta,

3
drivers/net/wireless/mediatek/mt76/mac80211.c
View File

@ -285,6 +285,7 @@ mt76_alloc_device(unsigned int size, const struct ieee80211_ops *ops)
spin_lock_init(&dev->cc_lock);
mutex_init(&dev->mutex);
init_waitqueue_head(&dev->tx_wait);
skb_queue_head_init(&dev->status_list);
return dev;
}
@ -326,6 +327,7 @@ int mt76_register_device(struct mt76_dev *dev, bool vht,
ieee80211_hw_set(hw, TX_FRAG_LIST);
ieee80211_hw_set(hw, MFP_CAPABLE);
ieee80211_hw_set(hw, AP_LINK_PS);
ieee80211_hw_set(hw, REPORTS_TX_ACK_STATUS);
wiphy->flags |= WIPHY_FLAG_IBSS_RSN;
@ -357,6 +359,7 @@ void mt76_unregister_device(struct mt76_dev *dev)
{
struct ieee80211_hw *hw = dev->hw;
mt76_tx_status_flush(dev, NULL);
ieee80211_unregister_hw(hw);
mt76_tx_free(dev);
}

48
drivers/net/wireless/mediatek/mt76/mt76.h
View File

@ -195,6 +195,8 @@ struct mt76_wcid {
u8 tx_rate_nss;
s8 max_txpwr_adj;
bool sw_iv;
u8 packet_id;
};
struct mt76_txq {
@ -233,6 +235,22 @@ struct mt76_rx_tid {
struct sk_buff *reorder_buf[];
};
#define MT_TX_CB_DMA_DONE BIT(0)
#define MT_TX_CB_TXS_DONE BIT(1)
#define MT_TX_CB_TXS_FAILED BIT(2)
#define MT_PACKET_ID_MASK GENMASK(7, 0)
#define MT_PACKET_ID_NO_ACK MT_PACKET_ID_MASK
#define MT_TX_STATUS_SKB_TIMEOUT HZ
struct mt76_tx_cb {
unsigned long jiffies;
u8 wcid;
u8 pktid;
u8 flags;
};
enum {
MT76_STATE_INITIALIZED,
MT76_STATE_RUNNING,
@ -400,6 +418,7 @@ struct mt76_dev {
const struct mt76_queue_ops *queue_ops;
wait_queue_head_t tx_wait;
struct sk_buff_head status_list;
unsigned long wcid_mask[MT76_N_WCIDS / BITS_PER_LONG];
@ -594,6 +613,13 @@ wcid_to_sta(struct mt76_wcid *wcid)
return container_of(ptr, struct ieee80211_sta, drv_priv);
}
static inline struct mt76_tx_cb *mt76_tx_skb_cb(struct sk_buff *skb)
{
BUILD_BUG_ON(sizeof(struct mt76_tx_cb) >
sizeof(IEEE80211_SKB_CB(skb)->status.status_driver_data));
return ((void *) IEEE80211_SKB_CB(skb)->status.status_driver_data);
}
int mt76_dma_tx_queue_skb(struct mt76_dev *dev, struct mt76_queue *q,
struct sk_buff *skb, struct mt76_wcid *wcid,
struct ieee80211_sta *sta);
@ -624,6 +650,28 @@ void mt76_rx_aggr_stop(struct mt76_dev *dev, struct mt76_wcid *wcid, u8 tid);
void mt76_wcid_key_setup(struct mt76_dev *dev, struct mt76_wcid *wcid,
struct ieee80211_key_conf *key);
int mt76_tx_status_skb_add(struct mt76_dev *dev, struct mt76_wcid *wcid,
struct sk_buff *skb);
struct sk_buff *mt76_tx_status_skb_get(struct mt76_dev *dev,
struct mt76_wcid *wcid, int pktid);
void mt76_tx_status_skb_done(struct mt76_dev *dev, struct sk_buff *skb);
void mt76_tx_complete_skb(struct mt76_dev *dev, struct sk_buff *skb);
static inline void
mt76_tx_status_check(struct mt76_dev *dev)
{
spin_lock_bh(&dev->status_list.lock);
mt76_tx_status_skb_get(dev, NULL, 0);
spin_unlock_bh(&dev->status_list.lock);
}
static inline void
mt76_tx_status_flush(struct mt76_dev *dev, struct mt76_wcid *wcid)
{
spin_lock_bh(&dev->status_list.lock);
mt76_tx_status_skb_get(dev, wcid, -1);
spin_unlock_bh(&dev->status_list.lock);
}
struct ieee80211_sta *mt76_rx_convert(struct sk_buff *skb);

1
drivers/net/wireless/mediatek/mt76/mt76x02.h
View File

@ -139,7 +139,6 @@ void mt76x02_set_coverage_class(struct ieee80211_hw *hw,
int mt76x02_set_rts_threshold(struct ieee80211_hw *hw, u32 val);
int mt76x02_insert_hdr_pad(struct sk_buff *skb);
void mt76x02_remove_hdr_pad(struct sk_buff *skb, int len);
void mt76x02_tx_complete(struct mt76_dev *dev, struct sk_buff *skb);
bool mt76x02_tx_status_data(struct mt76_dev *mdev, u8 *update);
void mt76x02_queue_rx_skb(struct mt76_dev *mdev, enum mt76_rxq_id q,
struct sk_buff *skb);

74
drivers/net/wireless/mediatek/mt76/mt76x02_mac.c
View File

@ -324,8 +324,6 @@ void mt76x02_mac_write_txwi(struct mt76x02_dev *dev, struct mt76x02_txwi *txwi,
else
txwi->wcid = 0xff;
txwi->pktid = 1;
if (wcid && wcid->sw_iv && key) {
u64 pn = atomic64_inc_return(&key->tx_pn);
ccmp_pn[0] = pn;
@ -371,8 +369,6 @@ void mt76x02_mac_write_txwi(struct mt76x02_dev *dev, struct mt76x02_txwi *txwi,
txwi->ack_ctl |= MT_TXWI_ACK_CTL_REQ;
if (info->flags & IEEE80211_TX_CTL_ASSIGN_SEQ)
txwi->ack_ctl |= MT_TXWI_ACK_CTL_NSEQ;
if (info->flags & IEEE80211_TX_CTL_RATE_CTRL_PROBE)
txwi->pktid |= MT_TXWI_PKTID_PROBE;
if ((info->flags & IEEE80211_TX_CTL_AMPDU) && sta) {
u8 ba_size = IEEE80211_MIN_AMPDU_BUF;
@ -425,9 +421,6 @@ mt76x02_mac_fill_tx_status(struct mt76x02_dev *dev,
info->status.ampdu_len = n_frames;
info->status.ampdu_ack_len = st->success ? n_frames : 0;
if (st->pktid & MT_TXWI_PKTID_PROBE)
info->flags |= IEEE80211_TX_CTL_RATE_CTRL_PROBE;
if (st->aggr)
info->flags |= IEEE80211_TX_CTL_AMPDU |
IEEE80211_TX_STAT_AMPDU;
@ -442,11 +435,19 @@ void mt76x02_send_tx_status(struct mt76x02_dev *dev,
struct mt76x02_tx_status *stat, u8 *update)
{
struct ieee80211_tx_info info = {};
struct ieee80211_sta *sta = NULL;
struct ieee80211_tx_status status = {
.info = &info
};
struct mt76_wcid *wcid = NULL;
struct mt76x02_sta *msta = NULL;
struct mt76_dev *mdev = &dev->mt76;
if (stat->pktid == MT_PACKET_ID_NO_ACK)
return;
rcu_read_lock();
spin_lock_bh(&mdev->status_list.lock);
if (stat->wcid < ARRAY_SIZE(dev->mt76.wcid))
wcid = rcu_dereference(dev->mt76.wcid[stat->wcid]);
@ -454,11 +455,19 @@ void mt76x02_send_tx_status(struct mt76x02_dev *dev,
void *priv;
priv = msta = container_of(wcid, struct mt76x02_sta, wcid);
sta = container_of(priv, struct ieee80211_sta,
drv_priv);
status.sta = container_of(priv, struct ieee80211_sta,
drv_priv);
}
if (msta && stat->aggr) {
if (wcid) {
if (stat->pktid)
status.skb = mt76_tx_status_skb_get(mdev, wcid,
stat->pktid);
if (status.skb)
status.info = IEEE80211_SKB_CB(status.skb);
}
if (msta && stat->aggr && !status.skb) {
u32 stat_val, stat_cache;
stat_val = stat->rate;
@ -472,20 +481,24 @@ void mt76x02_send_tx_status(struct mt76x02_dev *dev,
goto out;
}
mt76x02_mac_fill_tx_status(dev, &info, &msta->status,
mt76x02_mac_fill_tx_status(dev, status.info, &msta->status,
msta->n_frames);
msta->status = *stat;
msta->n_frames = 1;
*update = 0;
} else {
mt76x02_mac_fill_tx_status(dev, &info, stat, 1);
mt76x02_mac_fill_tx_status(dev, status.info, stat, 1);
*update = 1;
}
ieee80211_tx_status_noskb(dev->mt76.hw, sta, &info);
if (status.skb)
mt76_tx_status_skb_done(mdev, status.skb);
else
ieee80211_tx_status_ext(mt76_hw(dev), &status);
out:
spin_unlock_bh(&mdev->status_list.lock);
rcu_read_unlock();
}
@ -707,32 +720,23 @@ void mt76x02_mac_poll_tx_status(struct mt76x02_dev *dev, bool irq)
}
}
static void
mt76x02_mac_queue_txdone(struct mt76x02_dev *dev, struct sk_buff *skb,
void *txwi_ptr)
{
struct mt76x02_tx_info *txi = mt76x02_skb_tx_info(skb);
struct mt76x02_txwi *txwi = txwi_ptr;
mt76x02_mac_poll_tx_status(dev, false);
txi->tries = 0;
txi->jiffies = jiffies;
txi->wcid = txwi->wcid;
txi->pktid = txwi->pktid;
trace_mac_txdone_add(dev, txwi->wcid, txwi->pktid);
mt76x02_tx_complete(&dev->mt76, skb);
}
void mt76x02_tx_complete_skb(struct mt76_dev *mdev, struct mt76_queue *q,
struct mt76_queue_entry *e, bool flush)
{
struct mt76x02_dev *dev = container_of(mdev, struct mt76x02_dev, mt76);
struct mt76x02_txwi *txwi;
if (e->txwi)
mt76x02_mac_queue_txdone(dev, e->skb, &e->txwi->txwi);
else
if (!e->txwi) {
dev_kfree_skb_any(e->skb);
return;
}
mt76x02_mac_poll_tx_status(dev, false);
txwi = (struct mt76x02_txwi *) &e->txwi->txwi;
trace_mac_txdone_add(dev, txwi->wcid, txwi->pktid);
mt76_tx_complete_skb(mdev, e->skb);
}
EXPORT_SYMBOL_GPL(mt76x02_tx_complete_skb);
@ -817,6 +821,8 @@ void mt76x02_mac_work(struct work_struct *work)
if (!dev->beacon_mask)
mt76x02_check_mac_err(dev);
mt76_tx_status_check(&dev->mt76);
ieee80211_queue_delayed_work(mt76_hw(dev), &dev->mac_work,
MT_CALIBRATE_INTERVAL);
}

19
drivers/net/wireless/mediatek/mt76/mt76x02_mac.h
View File

@ -42,15 +42,6 @@ struct mt76x02_vif {
struct mt76_wcid group_wcid;
};
struct mt76x02_tx_info {
unsigned long jiffies;
u8 tries;
u8 wcid;
u8 pktid;
u8 retry;
};
DECLARE_EWMA(signal, 10, 8);
struct mt76x02_sta {
@ -153,8 +144,6 @@ enum mt76x2_phy_bandwidth {
#define MT_TXWI_ACK_CTL_NSEQ BIT(1)
#define MT_TXWI_ACK_CTL_BA_WINDOW GENMASK(7, 2)
#define MT_TXWI_PKTID_PROBE BIT(7)
struct mt76x02_txwi {
__le16 flags;
__le16 rate;
@ -190,14 +179,6 @@ static inline bool mt76x02_wait_for_mac(struct mt76_dev *dev)
return false;
}
static inline struct mt76x02_tx_info *
mt76x02_skb_tx_info(struct sk_buff *skb)
{
struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
return (void *)info->status.status_driver_data;
}
void mt76x02_txq_init(struct mt76x02_dev *dev, struct ieee80211_txq *txq);
void mt76x02_mac_set_short_preamble(struct mt76x02_dev *dev, bool enable);

25
drivers/net/wireless/mediatek/mt76/mt76x02_txrx.c
View File

@ -140,21 +140,6 @@ void mt76x02_tx_set_txpwr_auto(struct mt76x02_dev *dev, s8 txpwr)
}
EXPORT_SYMBOL_GPL(mt76x02_tx_set_txpwr_auto);
void mt76x02_tx_complete(struct mt76_dev *dev, struct sk_buff *skb)
{
struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
if (info->flags & IEEE80211_TX_CTL_AMPDU) {
ieee80211_free_txskb(dev->hw, skb);
} else {
ieee80211_tx_info_clear_status(info);
info->status.rates[0].idx = -1;
info->flags |= IEEE80211_TX_STAT_ACK;
ieee80211_tx_status(dev->hw, skb);
}
}
EXPORT_SYMBOL_GPL(mt76x02_tx_complete);
bool mt76x02_tx_status_data(struct mt76_dev *mdev, u8 *update)
{
struct mt76x02_dev *dev = container_of(mdev, struct mt76x02_dev, mt76);
@ -169,14 +154,15 @@ bool mt76x02_tx_status_data(struct mt76_dev *mdev, u8 *update)
}
EXPORT_SYMBOL_GPL(mt76x02_tx_status_data);
int mt76x02_tx_prepare_skb(struct mt76_dev *mdev, void *txwi,
int mt76x02_tx_prepare_skb(struct mt76_dev *mdev, void *txwi_ptr,
struct sk_buff *skb, struct mt76_queue *q,
struct mt76_wcid *wcid, struct ieee80211_sta *sta,
u32 *tx_info)
{
struct mt76x02_dev *dev = container_of(mdev, struct mt76x02_dev, mt76);
struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
struct mt76x02_txwi *txwi = txwi_ptr;
int qsel = MT_QSEL_EDCA;
int pid;
int ret;
if (q == &dev->mt76.q_tx[MT_TXQ_PSD] && wcid && wcid->idx < 128)
@ -184,11 +170,14 @@ int mt76x02_tx_prepare_skb(struct mt76_dev *mdev, void *txwi,
mt76x02_mac_write_txwi(dev, txwi, skb, wcid, sta, skb->len);
pid = mt76_tx_status_skb_add(mdev, wcid, skb);
txwi->pktid = pid;
ret = mt76x02_insert_hdr_pad(skb);
if (ret < 0)
return ret;
if (info->flags & IEEE80211_TX_CTL_RATE_CTRL_PROBE)
if (pid && pid != MT_PACKET_ID_NO_ACK)
qsel = MT_QSEL_MGMT;
*tx_info = FIELD_PREP(MT_TXD_INFO_QSEL, qsel) |

42
drivers/net/wireless/mediatek/mt76/mt76x02_usb_core.c
View File

@ -30,7 +30,7 @@ void mt76x02u_tx_complete_skb(struct mt76_dev *mdev, struct mt76_queue *q,
struct mt76_queue_entry *e, bool flush)
{
mt76x02u_remove_dma_hdr(e->skb);
mt76x02_tx_complete(mdev, e->skb);
mt76_tx_complete_skb(mdev, e->skb);
}
EXPORT_SYMBOL_GPL(mt76x02u_tx_complete_skb);
@ -67,15 +67,28 @@ int mt76x02u_skb_dma_info(struct sk_buff *skb, int port, u32 flags)
return 0;
}
static int
mt76x02u_set_txinfo(struct sk_buff *skb, struct mt76_wcid *wcid, u8 ep)
int mt76x02u_tx_prepare_skb(struct mt76_dev *mdev, void *data,
struct sk_buff *skb, struct mt76_queue *q,
struct mt76_wcid *wcid, struct ieee80211_sta *sta,
u32 *tx_info)
{
struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
struct mt76x02_dev *dev = container_of(mdev, struct mt76x02_dev, mt76);
struct mt76x02_txwi *txwi;
enum mt76_qsel qsel;
int len = skb->len;
u32 flags;
int pid;
if ((info->flags & IEEE80211_TX_CTL_RATE_CTRL_PROBE) ||
ep == MT_EP_OUT_HCCA)
mt76x02_insert_hdr_pad(skb);
txwi = skb_push(skb, sizeof(struct mt76x02_txwi));
mt76x02_mac_write_txwi(dev, txwi, skb, wcid, sta, len);
pid = mt76_tx_status_skb_add(mdev, wcid, skb);
txwi->pktid = pid;
if ((pid && pid != MT_PACKET_ID_NO_ACK) ||
q2ep(q->hw_idx) == MT_EP_OUT_HCCA)
qsel = MT_QSEL_MGMT;
else
qsel = MT_QSEL_EDCA;
@ -87,21 +100,4 @@ mt76x02u_set_txinfo(struct sk_buff *skb, struct mt76_wcid *wcid, u8 ep)
return mt76x02u_skb_dma_info(skb, WLAN_PORT, flags);
}
int mt76x02u_tx_prepare_skb(struct mt76_dev *mdev, void *data,
struct sk_buff *skb, struct mt76_queue *q,
struct mt76_wcid *wcid, struct ieee80211_sta *sta,
u32 *tx_info)
{
struct mt76x02_dev *dev = container_of(mdev, struct mt76x02_dev, mt76);
struct mt76x02_txwi *txwi;
int len = skb->len;
mt76x02_insert_hdr_pad(skb);
txwi = skb_push(skb, sizeof(struct mt76x02_txwi));
mt76x02_mac_write_txwi(dev, txwi, skb, wcid, sta, len);
return mt76x02u_set_txinfo(skb, wcid, q2ep(q->hw_idx));
}
EXPORT_SYMBOL_GPL(mt76x02u_tx_prepare_skb);

1
drivers/net/wireless/mediatek/mt76/mt76x02_util.c
View File

@ -215,6 +215,7 @@ int mt76x02_sta_remove(struct ieee80211_hw *hw, struct ieee80211_vif *vif,
int i;
mutex_lock(&dev->mt76.mutex);
mt76_tx_status_flush(&dev->mt76, &msta->wcid);
rcu_assign_pointer(dev->mt76.wcid[idx], NULL);
for (i = 0; i < ARRAY_SIZE(sta->txq); i++)
mt76_txq_remove(&dev->mt76, sta->txq[i]);

111
drivers/net/wireless/mediatek/mt76/tx.c
View File

@ -103,6 +103,117 @@ mt76_check_agg_ssn(struct mt76_txq *mtxq, struct sk_buff *skb)
mtxq->agg_ssn = le16_to_cpu(hdr->seq_ctrl) + 0x10;
}
static void
__mt76_tx_status_skb_done(struct mt76_dev *dev, struct sk_buff *skb, u8 flags)
{
struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
struct mt76_tx_cb *cb = mt76_tx_skb_cb(skb);
u8 done = MT_TX_CB_DMA_DONE | MT_TX_CB_TXS_DONE;
flags |= cb->flags;
cb->flags = flags;
if ((flags & done) != done)
return;
__skb_unlink(skb, &dev->status_list);
/* Tx status can be unreliable. if it fails, mark the frame as ACKed */
if (flags & MT_TX_CB_TXS_FAILED) {
ieee80211_tx_info_clear_status(info);
info->status.rates[0].idx = -1;
info->flags |= IEEE80211_TX_STAT_ACK;
}
ieee80211_tx_status(dev->hw, skb);
}
void
mt76_tx_status_skb_done(struct mt76_dev *dev, struct sk_buff *skb)
{
__mt76_tx_status_skb_done(dev, skb, MT_TX_CB_TXS_DONE);
}
EXPORT_SYMBOL_GPL(mt76_tx_status_skb_done);
int
mt76_tx_status_skb_add(struct mt76_dev *dev, struct mt76_wcid *wcid,
struct sk_buff *skb)
{
struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
struct mt76_tx_cb *cb = mt76_tx_skb_cb(skb);
int pid;
if (!wcid)
return 0;
if (info->flags & IEEE80211_TX_CTL_NO_ACK)
return MT_PACKET_ID_NO_ACK;
if (!(info->flags & (IEEE80211_TX_CTL_REQ_TX_STATUS |
IEEE80211_TX_CTL_RATE_CTRL_PROBE)))
return 0;
spin_lock_bh(&dev->status_list.lock);
memset(cb, 0, sizeof(*cb));
wcid->packet_id = (wcid->packet_id + 1) & MT_PACKET_ID_MASK;
if (!wcid->packet_id || wcid->packet_id == MT_PACKET_ID_NO_ACK)
wcid->packet_id = 1;
pid = wcid->packet_id;
cb->wcid = wcid->idx;
cb->pktid = pid;
cb->jiffies = jiffies;
__skb_queue_tail(&dev->status_list, skb);
spin_unlock_bh(&dev->status_list.lock);
return pid;
}
EXPORT_SYMBOL_GPL(mt76_tx_status_skb_add);
struct sk_buff *
mt76_tx_status_skb_get(struct mt76_dev *dev, struct mt76_wcid *wcid, int pktid)
{
struct sk_buff *skb, *tmp;
if (pktid == MT_PACKET_ID_NO_ACK)
return NULL;
skb_queue_walk_safe(&dev->status_list, skb, tmp) {
struct mt76_tx_cb *cb = mt76_tx_skb_cb(skb);
if (wcid && cb->wcid != wcid->idx)
continue;
if (cb->pktid == pktid)
return skb;
if (!pktid &&
!time_after(jiffies, cb->jiffies + MT_TX_STATUS_SKB_TIMEOUT))
continue;
__mt76_tx_status_skb_done(dev, skb, MT_TX_CB_TXS_FAILED |
MT_TX_CB_TXS_DONE);
}
return NULL;
}
EXPORT_SYMBOL_GPL(mt76_tx_status_skb_get);
void mt76_tx_complete_skb(struct mt76_dev *dev, struct sk_buff *skb)
{
if (!skb->prev) {
ieee80211_free_txskb(dev->hw, skb);
return;
}
spin_lock_bh(&dev->status_list.lock);
__mt76_tx_status_skb_done(dev, skb, MT_TX_CB_DMA_DONE);
spin_unlock_bh(&dev->status_list.lock);
}
EXPORT_SYMBOL_GPL(mt76_tx_complete_skb);
void
mt76_tx(struct mt76_dev *dev, struct ieee80211_sta *sta,
struct mt76_wcid *wcid, struct sk_buff *skb)

1
drivers/net/wireless/mediatek/mt76/usb.c
View File

@ -700,6 +700,7 @@ mt76u_tx_queue_skb(struct mt76_dev *dev, struct mt76_queue *q,
if (q->queued == q->ndesc)
return -ENOSPC;
skb->prev = skb->next = NULL;
err = dev->drv->tx_prepare_skb(dev, NULL, skb, q, wcid, sta, NULL);
if (err < 0)
return err;