On Thu, Sep 03, 2020 at 10:43:02AM +0200, Christoph Hellwig wrote: > On Tue, Sep 01, 2020 at 07:38:10PM +0200, Thomas Bogendoerfer wrote: > > this is the problem: > > > > /* Always check for received packets. */ > > sgiseeq_rx(dev, sp, hregs, sregs); > > > > so the driver will look at the rx descriptor on every interrupt, so > > we cache the rx descriptor on the first interrupt and if there was > > $no rx packet, we will only see it, if cache line gets flushed for > > some other reason. > > That means a transfer back to device ownership is missing after a > (negative) check. E.g. something like this for the particular problem, although there might be other hiding elsewhere: diff --git a/drivers/net/ethernet/seeq/sgiseeq.c b/drivers/net/ethernet/seeq/sgiseeq.c index 8507ff2420143a..a1c7be8a0d1e5d 100644 --- a/drivers/net/ethernet/seeq/sgiseeq.c +++ b/drivers/net/ethernet/seeq/sgiseeq.c @@ -403,6 +403,8 @@ static inline void sgiseeq_rx(struct net_device *dev, struct sgiseeq_private *sp rd = &sp->rx_desc[sp->rx_new]; dma_sync_desc_cpu(dev, rd); } + dma_sync_desc_dev(dev, rd); + dma_sync_desc_cpu(dev, &sp->rx_desc[orig_end]); sp->rx_desc[orig_end].rdma.cntinfo &= ~(HPCDMA_EOR); dma_sync_desc_dev(dev, &sp->rx_desc[orig_end]);
