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SubjectRe: [PATCH v4 2/2] rtw88: pci: Use DMA sync instead of remapping in RX ISR
Jian-Hong Pan <jian-hong@endlessm.com> 於 2019年7月11日 週四 下午1:25寫道:
>
> 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>
> ---

Sorry, also forget to place the version difference here

v2:
- New patch by following [PATCH v3 1/2] rtw88: pci: Rearrange the
memory usage for skb in RX ISR.

v3:
- Remove rtw_pci_sync_rx_desc_cpu and call dma_sync_single_for_cpu in
rtw_pci_rx_isr directly.
- Remove the return value of rtw_pci_sync_rx_desc_device.
- Use DMA_FROM_DEVICE instead of PCI_DMA_FROMDEVICE.

v4:
- Same as v3.

> 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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