> On Thu, Oct 24, 2019 at 12:23:16AM +0200, Lorenzo Bianconi wrote:
> > mt76 dma layer is supposed to unmap skb data buffers while keep txwi
> > mapped on hw dma ring. At the moment mt76 wrongly unmap txwi or does
> > not unmap data fragments in even positions for non-linear skbs. This
> > issue may result in hw hangs with A-MSDU if the system relies on IOMMU
> > or SWIOTLB. Fix this behaviour properly unmapping data fragments on
> > non-linear skbs.
>
> If we have to keep txwi mapped, before unmap fragments, when then
> txwi is unmaped ?
txwi are mapped when they are crated in mt76_alloc_txwi(). Whenever we need to
modify them we sync the DMA in mt76_dma_tx_queue_skb(). txwi are unmapped in
mt76_tx_free() at driver unload.
Regards,
Lorenzo
>
> Stanislaw
>
> > Fixes: 17f1de56df05 ("mt76: add common code shared between multiple chipsets")
> > Signed-off-by: Lorenzo Bianconi <lorenzo@xxxxxxxxxx>
> > ---
> > drivers/net/wireless/mediatek/mt76/dma.c | 10 +++++++---
> > 1 file changed, 7 insertions(+), 3 deletions(-)
> >
> > diff --git a/drivers/net/wireless/mediatek/mt76/dma.c b/drivers/net/wireless/mediatek/mt76/dma.c
> > index c747eb24581c..8c27956875e7 100644
> > --- a/drivers/net/wireless/mediatek/mt76/dma.c
> > +++ b/drivers/net/wireless/mediatek/mt76/dma.c
> > @@ -93,11 +93,14 @@ static void
> > mt76_dma_tx_cleanup_idx(struct mt76_dev *dev, struct mt76_queue *q, int idx,
> > struct mt76_queue_entry *prev_e)
> > {
> > - struct mt76_queue_entry *e = &q->entry[idx];
> > __le32 __ctrl = READ_ONCE(q->desc[idx].ctrl);
> > + struct mt76_queue_entry *e = &q->entry[idx];
> > u32 ctrl = le32_to_cpu(__ctrl);
> > + bool mcu = e->skb && !e->txwi;
> > + bool first = e->skb == DMA_DUMMY_DATA || e->txwi == DMA_DUMMY_DATA ||
> > + (e->skb && !skb_is_nonlinear(e->skb));
> >
> > - if (!e->txwi || !e->skb) {
> > + if (!first || mcu) {
> > __le32 addr = READ_ONCE(q->desc[idx].buf0);
> > u32 len = FIELD_GET(MT_DMA_CTL_SD_LEN0, ctrl);
> >
> > @@ -105,7 +108,8 @@ mt76_dma_tx_cleanup_idx(struct mt76_dev *dev, struct mt76_queue *q, int idx,
> > DMA_TO_DEVICE);
> > }
> >
> > - if (!(ctrl & MT_DMA_CTL_LAST_SEC0)) {
> > + if (!(ctrl & MT_DMA_CTL_LAST_SEC0) ||
> > + e->txwi == DMA_DUMMY_DATA) {
> > __le32 addr = READ_ONCE(q->desc[idx].buf1);
> > u32 len = FIELD_GET(MT_DMA_CTL_SD_LEN1, ctrl);
> >
> > --
> > 2.21.0
> >
>
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