On Tue, Jul 30, 2019 at 2:15 PM <guoren@xxxxxxxxxx> wrote:
>
> From: Guo Ren <ren_guo@xxxxxxxxx>
>
> If arch didn't define dma_r/wmb(), linux will use w/rmb instead. Csky
> use bar.xxx to implement mb() and that will cause problem when sync data
> with dma device, becasue bar.xxx couldn't guarantee bus transactions
> finished at outside bus level. We must use sync.s instead of bar.xxx for
> dma data synchronization and it will guarantee retirement after getting
> the bus bresponse.
>
> Signed-off-by: Guo Ren <ren_guo@xxxxxxxxx>
This change looks good to me, but I think your regular barriers
(mb, rmb, wmb) are still wrong: These are meant to be the superset
of dma_{r,w}mb and smp_{,r,w}mb, and synchronize
against both SMP and DMA interactions.
I suspect you can drop the '.s' for non-SMP builds. What I don't
see is whether you might need to add '.i' for dma_wmb() or
dma_rmb().
Arnd
