Re: [REGRESSION] Recent swiotlb DMA_FROM_DEVICE fixes break ath9k-based AP

Oleksandr Natalenko
2022-03-25T07:12:48Z

Hello.

On čtvrtek 24. března 2022 18:07:29 CET Toke Høiland-Jørgensen wrote:
> Right, but is that sync_for_device call really needed? AFAICT, that
> ath9k_hw_process_rxdesc_edma() invocation doesn't actually modify any of
> the data when it returns EINPROGRESS, so could we just skip it? Like
> the patch below? Or am I misunderstanding the semantics here?
>
> -Toke
>
>
> diff --git a/drivers/net/wireless/ath/ath9k/recv.c b/drivers/net/wireless/ath/ath9k/recv.c
> index 0c0624a3b40d..19244d4c0ada 100644
> --- a/drivers/net/wireless/ath/ath9k/recv.c
> +++ b/drivers/net/wireless/ath/ath9k/recv.c
> @@ -647,12 +647,8 @@ static bool ath_edma_get_buffers(struct ath_softc *sc,
> common->rx_bufsize, DMA_FROM_DEVICE);
>
> ret = ath9k_hw_process_rxdesc_edma(ah, rs, skb->data);
> - if (ret == -EINPROGRESS) {
> - /*let device gain the buffer again*/
> - dma_sync_single_for_device(sc->dev, bf->bf_buf_addr,
> - common->rx_bufsize, DMA_FROM_DEVICE);
> + if (ret == -EINPROGRESS)
> return false;
> - }
>
> __skb_unlink(skb, &rx_edma->rx_fifo);
> if (ret == -EINVAL) {

With this patch and both ddbd89deb7d3+aa6f8dcbab47 in place the AP works for me.

Thanks.

--
Oleksandr Natalenko (post-factum)