On Wed, Nov 11, 2015 at 1:07 AM, Måns Rullgård <m...@mansr.com> wrote: > Andy Shevchenko <andy.shevche...@gmail.com> writes:
>>>>> + nb8800_writel(priv, NB8800_TX_DESC_ADDR, txb->dma_desc); >>>>> + wmb(); /* ensure desc addr is written before starting >>>>> DMA */ >>>> >>>> Hm… Have I missed corresponding rmb() ? If it's about MMIO, perhaps >>>> mmiowb() ? >>> >>> Possibly. >> >> Standalone wmb() doesn't make sense. > > It does if you need to enforce ordering between normal and I/O memory. > In fact, since the descriptor is filled in using normal memory accesses, > my understanding is that mmiowb() would be insufficient here. The > comment could be improved, however. Can you then explain what exactly you are assured against in all cases where you are using wmb()s? It seems I don't recognize this part in some excerpts. -- With Best Regards, Andy Shevchenko -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
