On Mon, 19 Oct 2020 08:57:03 +0000 Joel Stanley wrote: > > diff --git a/drivers/net/ethernet/faraday/ftgmac100.c > > b/drivers/net/ethernet/faraday/ftgmac100.c > > index 00024dd41147..9a99a87f29f3 100644 > > --- a/drivers/net/ethernet/faraday/ftgmac100.c > > +++ b/drivers/net/ethernet/faraday/ftgmac100.c > > @@ -804,7 +804,8 @@ static netdev_tx_t ftgmac100_hard_start_xmit(struct > > sk_buff *skb, > > * before setting the OWN bit on the first descriptor. > > */ > > dma_wmb(); > > - first->txdes0 = cpu_to_le32(f_ctl_stat); > > + WRITE_ONCE(first->txdes0, cpu_to_le32(f_ctl_stat)); > > + READ_ONCE(first->txdes0); > > I understand what you're trying to do here, but I'm not sure that this > is the correct way to go about it. > > It does cause the compiler to produce a store and then a load.
+1 @first is system memory from dma_alloc_coherent(), right? You shouldn't have to do this. Is coherent DMA memory broken on your platform?
