mt76: dma: fix buffer unmap with non-linear skbs

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.

Fixes: 17f1de56df05 ("mt76: add common code shared between multiple chipsets")
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>

diff --git a/drivers/net/wireless/mediatek/mt76/dma.c b/drivers/net/wireless/mediatek/mt76/dma.c
index c747eb24581c42683f93f6e285a660e2edd9daea..8f69d00bd940a98aaa84a0166c7375357ecab82a 100644 (file)
--- a/drivers/net/wireless/mediatek/mt76/dma.c
+++ b/drivers/net/wireless/mediatek/mt76/dma.c
@@ -53,8 +53,10 @@ mt76_dma_add_buf(struct mt76_dev *dev, struct mt76_queue *q,
        u32 ctrl;
        int i, idx = -1;
 
-       if (txwi)
+       if (txwi) {
                q->entry[q->head].txwi = DMA_DUMMY_DATA;
+               q->entry[q->head].skip_buf0 = true;
+       }
 
        for (i = 0; i < nbufs; i += 2, buf += 2) {
                u32 buf0 = buf[0].addr, buf1 = 0;
@@ -97,7 +99,7 @@ mt76_dma_tx_cleanup_idx(struct mt76_dev *dev, struct mt76_queue *q, int idx,
        __le32 __ctrl = READ_ONCE(q->desc[idx].ctrl);
        u32 ctrl = le32_to_cpu(__ctrl);
 
-       if (!e->txwi || !e->skb) {
+       if (!e->skip_buf0) {
                __le32 addr = READ_ONCE(q->desc[idx].buf0);
                u32 len = FIELD_GET(MT_DMA_CTL_SD_LEN0, ctrl);
 

diff --git a/drivers/net/wireless/mediatek/mt76/mt76.h b/drivers/net/wireless/mediatek/mt76/mt76.h
index dc468ed9434a7ac894b25542516fa4c472a44c89..8aec7ccf2d79b45ccbcd9388ab72e97e4c98bb2c 100644 (file)
--- a/drivers/net/wireless/mediatek/mt76/mt76.h
+++ b/drivers/net/wireless/mediatek/mt76/mt76.h
@@ -93,8 +93,9 @@ struct mt76_queue_entry {
                struct urb *urb;
        };
        enum mt76_txq_id qid;
-       bool schedule;
-       bool done;
+       bool skip_buf0:1;
+       bool schedule:1;
+       bool done:1;
 };
 
 struct mt76_queue_regs {