Since linux-6.2-rc1 the mediatek mt76 wlan driver suffers from problems https://bugzilla.kernel.org/show_bug.cgi?id=216901. I bisected this to commit cd372b8c99c5a5cf6a464acebb7e4a79af7ec8ae and noticed that the if (txwi) { q->entry[q->head].txwi = DMA_DUMMY_DATA; q->entry[q->head].skip_buf0 = true; } part is moved from the beginning of mt76_dma_add_buf to the inside of the for loop. But q->head is modified at the beginning of this loop. This patch puts at the beginning of mt76_dma_add_buf diff -aur linux-6.2-rc3.old/drivers/net/wireless/mediatek/mt76/dma.c linux-6.2-rc3/drivers/net/wireless/mediatek/mt76/dma.c --- linux-6.2-rc3.old/drivers/net/wireless/mediatek/mt76/dma.c 2023- 01-08 18:49:43.000000000 +0100 +++ linux-6.2-rc3/drivers/net/wireless/mediatek/mt76/dma.c 2023- 01-09 22:07:29.533248047 +0100 @@ -215,6 +215,11 @@ u32 ctrl; int i, idx = -1; + 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; @@ -238,11 +243,6 @@ ctrl = FIELD_PREP(MT_DMA_CTL_SD_LEN0, buf[0].len) | MT_DMA_CTL_TO_HOST; } else { - if (txwi) { - q->entry[q->head].txwi = DMA_DUMMY_DATA; - q->entry[q->head].skip_buf0 = true; - } - if (buf[0].skip_unmap) entry->skip_buf0 = true; entry->skip_buf1 = i == nbufs - 1; Bert Karwatzki
