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Subject[PATCH v4 2/2] rtw88: pci: Use DMA sync instead of remapping in RX ISR
Date
Since each skb in RX ring is reused instead of new allocation, we can
treat the DMA in a more efficient way by DMA synchronization.

Signed-off-by: Jian-Hong Pan <jian-hong@endlessm.com>
Cc: <stable@vger.kernel.org>
---
drivers/net/wireless/realtek/rtw88/pci.c | 24 +++++++++++++++++++++---
1 file changed, 21 insertions(+), 3 deletions(-)

diff --git a/drivers/net/wireless/realtek/rtw88/pci.c b/drivers/net/wireless/realtek/rtw88/pci.c
index c415f5e94fed..68fae52151dd 100644
--- a/drivers/net/wireless/realtek/rtw88/pci.c
+++ b/drivers/net/wireless/realtek/rtw88/pci.c
@@ -206,6 +206,23 @@ static int rtw_pci_reset_rx_desc(struct rtw_dev *rtwdev, struct sk_buff *skb,
return 0;
}

+static void rtw_pci_sync_rx_desc_device(struct rtw_dev *rtwdev, dma_addr_t dma,
+ struct rtw_pci_rx_ring *rx_ring,
+ u32 idx, u32 desc_sz)
+{
+ struct device *dev = rtwdev->dev;
+ struct rtw_pci_rx_buffer_desc *buf_desc;
+ int buf_sz = RTK_PCI_RX_BUF_SIZE;
+
+ dma_sync_single_for_device(dev, dma, buf_sz, DMA_FROM_DEVICE);
+
+ buf_desc = (struct rtw_pci_rx_buffer_desc *)(rx_ring->r.head +
+ idx * desc_sz);
+ memset(buf_desc, 0, sizeof(*buf_desc));
+ buf_desc->buf_size = cpu_to_le16(RTK_PCI_RX_BUF_SIZE);
+ buf_desc->dma = cpu_to_le32(dma);
+}
+
static int rtw_pci_init_rx_ring(struct rtw_dev *rtwdev,
struct rtw_pci_rx_ring *rx_ring,
u8 desc_size, u32 len)
@@ -782,8 +799,8 @@ static void rtw_pci_rx_isr(struct rtw_dev *rtwdev, struct rtw_pci *rtwpci,
rtw_pci_dma_check(rtwdev, ring, cur_rp);
skb = ring->buf[cur_rp];
dma = *((dma_addr_t *)skb->cb);
- pci_unmap_single(rtwpci->pdev, dma, RTK_PCI_RX_BUF_SIZE,
- PCI_DMA_FROMDEVICE);
+ dma_sync_single_for_cpu(rtwdev->dev, dma, RTK_PCI_RX_BUF_SIZE,
+ DMA_FROM_DEVICE);
rx_desc = skb->data;
chip->ops->query_rx_desc(rtwdev, rx_desc, &pkt_stat, &rx_status);

@@ -818,7 +835,8 @@ static void rtw_pci_rx_isr(struct rtw_dev *rtwdev, struct rtw_pci *rtwpci,

next_rp:
/* new skb delivered to mac80211, re-enable original skb DMA */
- rtw_pci_reset_rx_desc(rtwdev, skb, ring, cur_rp, buf_desc_sz);
+ rtw_pci_sync_rx_desc_device(rtwdev, dma, ring, cur_rp,
+ buf_desc_sz);

/* host read next element in ring */
if (++cur_rp >= ring->r.len)
--
2.22.0
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