rtw88: kick off TX packets once for higher efficiency

Driver used to kick off every TX packets, that will waste some
time while we can do better to kick off the TX packets once after
they are all prepared to be transmitted.

For PCI, it uses DMA engine to transfer the SKBs to the device,
and the transition of the state of the DMA engine could be a cost.
Driver can save some time to kick off multiple SKBs once so that
the DMA engine will have only one transition.

So, split rtw_hci_ops::tx() to rtw_hci_ops::tx_write() and
rtw_hci_ops::tx_kick_off() to explicitly kick the SKBs off after
they are written to the prepared buffer. For packets come from
ieee80211_ops::tx(), write one and then kick it off immediately.
For packets queued in TX queue, which come from
ieee80211_ops::wake_tx_queue(), we can dequeue them, write them
to the buffer, and then kick them off together.

Signed-off-by: Yan-Hsuan Chuang <yhchuang@realtek.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/20200312080852.16684-6-yhchuang@realtek.com

1 files changed, 67 insertions, 25 deletions

diff --git a/drivers/net/wireless/realtek/rtw88/pci.c b/drivers/net/wireless/realtek/rtw88/pci.c
index 812944a7b4bd..e37c71495c0d 100644
--- a/drivers/net/wireless/realtek/rtw88/pci.c
+++ b/drivers/net/wireless/realtek/rtw88/pci.c
@@ -691,9 +691,34 @@ static void rtw_pci_dma_check(struct rtw_dev *rtwdev,
 	rtwpci->rx_tag = (rtwpci->rx_tag + 1) % RX_TAG_MAX;
 }
 
-static int rtw_pci_xmit(struct rtw_dev *rtwdev,
-			struct rtw_tx_pkt_info *pkt_info,
-			struct sk_buff *skb, u8 queue)
+static void rtw_pci_tx_kick_off_queue(struct rtw_dev *rtwdev, u8 queue)
+{
+	struct rtw_pci *rtwpci = (struct rtw_pci *)rtwdev->priv;
+	struct rtw_pci_tx_ring *ring;
+	u32 bd_idx;
+
+	ring = &rtwpci->tx_rings[queue];
+	bd_idx = rtw_pci_tx_queue_idx_addr[queue];
+
+	spin_lock_bh(&rtwpci->irq_lock);
+	rtw_pci_deep_ps_leave(rtwdev);
+	rtw_write16(rtwdev, bd_idx, ring->r.wp & TRX_BD_IDX_MASK);
+	spin_unlock_bh(&rtwpci->irq_lock);
+}
+
+static void rtw_pci_tx_kick_off(struct rtw_dev *rtwdev)
+{
+	struct rtw_pci *rtwpci = (struct rtw_pci *)rtwdev->priv;
+	u8 queue;
+
+	for (queue = 0; queue < RTK_MAX_TX_QUEUE_NUM; queue++)
+		if (test_and_clear_bit(queue, rtwpci->tx_queued))
+			rtw_pci_tx_kick_off_queue(rtwdev, queue);
+}
+
+static int rtw_pci_tx_write_data(struct rtw_dev *rtwdev,
+				 struct rtw_tx_pkt_info *pkt_info,
+				 struct sk_buff *skb, u8 queue)
 {
 	struct rtw_pci *rtwpci = (struct rtw_pci *)rtwdev->priv;
 	struct rtw_chip_info *chip = rtwdev->chip;
@@ -706,7 +731,6 @@ static int rtw_pci_xmit(struct rtw_dev *rtwdev,
 	u32 psb_len;
 	u8 *pkt_desc;
 	struct rtw_pci_tx_buffer_desc *buf_desc;
-	u32 bd_idx;
 
 	ring = &rtwpci->tx_rings[queue];
 
@@ -745,22 +769,17 @@ static int rtw_pci_xmit(struct rtw_dev *rtwdev,
 
 	spin_lock_bh(&rtwpci->irq_lock);
 
-	rtw_pci_deep_ps_leave(rtwdev);
 	skb_queue_tail(&ring->queue, skb);
 
-	/* kick off tx queue */
-	if (queue != RTW_TX_QUEUE_BCN) {
-		if (++ring->r.wp >= ring->r.len)
-			ring->r.wp = 0;
-		bd_idx = rtw_pci_tx_queue_idx_addr[queue];
-		rtw_write16(rtwdev, bd_idx, ring->r.wp & TRX_BD_IDX_MASK);
-	} else {
-		u32 reg_bcn_work;
-
-		reg_bcn_work = rtw_read8(rtwdev, RTK_PCI_TXBD_BCN_WORK);
-		reg_bcn_work |= BIT_PCI_BCNQ_FLAG;
-		rtw_write8(rtwdev, RTK_PCI_TXBD_BCN_WORK, reg_bcn_work);
-	}
+	if (queue == RTW_TX_QUEUE_BCN)
+		goto out_unlock;
+
+	/* update write-index, and kick it off later */
+	set_bit(queue, rtwpci->tx_queued);
+	if (++ring->r.wp >= ring->r.len)
+		ring->r.wp = 0;
+
+out_unlock:
 	spin_unlock_bh(&rtwpci->irq_lock);
 
 	return 0;
@@ -771,36 +790,58 @@ static int rtw_pci_write_data_rsvd_page(struct rtw_dev *rtwdev, u8 *buf,
 {
 	struct sk_buff *skb;
 	struct rtw_tx_pkt_info pkt_info = {0};
+	u8 reg_bcn_work;
+	int ret;
 
 	skb = rtw_tx_write_data_rsvd_page_get(rtwdev, &pkt_info, buf, size);
 	if (!skb)
 		return -ENOMEM;
 
-	return rtw_pci_xmit(rtwdev, &pkt_info, skb, RTW_TX_QUEUE_BCN);
+	ret = rtw_pci_tx_write_data(rtwdev, &pkt_info, skb, RTW_TX_QUEUE_BCN);
+	if (ret) {
+		rtw_err(rtwdev, "failed to write rsvd page data\n");
+		return ret;
+	}
+
+	/* reserved pages go through beacon queue */
+	reg_bcn_work = rtw_read8(rtwdev, RTK_PCI_TXBD_BCN_WORK);
+	reg_bcn_work |= BIT_PCI_BCNQ_FLAG;
+	rtw_write8(rtwdev, RTK_PCI_TXBD_BCN_WORK, reg_bcn_work);
+
+	return 0;
 }
 
 static int rtw_pci_write_data_h2c(struct rtw_dev *rtwdev, u8 *buf, u32 size)
 {
 	struct sk_buff *skb;
 	struct rtw_tx_pkt_info pkt_info = {0};
+	int ret;
 
 	skb = rtw_tx_write_data_h2c_get(rtwdev, &pkt_info, buf, size);
 	if (!skb)
 		return -ENOMEM;
 
-	return rtw_pci_xmit(rtwdev, &pkt_info, skb, RTW_TX_QUEUE_H2C);
+	ret = rtw_pci_tx_write_data(rtwdev, &pkt_info, skb, RTW_TX_QUEUE_H2C);
+	if (ret) {
+		rtw_err(rtwdev, "failed to write h2c data\n");
+		return ret;
+	}
+
+	rtw_pci_tx_kick_off_queue(rtwdev, RTW_TX_QUEUE_H2C);
+
+	return 0;
 }
 
-static int rtw_pci_tx(struct rtw_dev *rtwdev,
-		      struct rtw_tx_pkt_info *pkt_info,
-		      struct sk_buff *skb)
+static int rtw_pci_tx_write(struct rtw_dev *rtwdev,
+			    struct rtw_tx_pkt_info *pkt_info,
+			    struct sk_buff *skb)
 {
 	struct rtw_pci *rtwpci = (struct rtw_pci *)rtwdev->priv;
 	struct rtw_pci_tx_ring *ring;
 	u8 queue = rtw_hw_queue_mapping(skb);
 	int ret;
 
-	ret = rtw_pci_xmit(rtwdev, pkt_info, skb, queue);
+	ret = rtw_pci_tx_write_data(rtwdev, pkt_info, skb, queue);
 	if (ret)
 		return ret;
 
@@ -1374,7 +1415,8 @@ static void rtw_pci_destroy(struct rtw_dev *rtwdev, struct pci_dev *pdev)
 }
 
 static struct rtw_hci_ops rtw_pci_ops = {
-	.tx = rtw_pci_tx,
+	.tx_write = rtw_pci_tx_write,
+	.tx_kick_off = rtw_pci_tx_kick_off,
 	.setup = rtw_pci_setup,
 	.start = rtw_pci_start,
 	.stop = rtw_pci_stop,