Re: [PATCH edk2-platforms 1/2] Silicon/SynQuacer/PlatformDxe: set NETSEC DMA as coherent

["Ard Biesheuvel" <ard.biesheuvel@linaro.org>]

On Thu, 28 Nov 2019 at 16:19, Leif Lindholm <leif.lindholm@linaro.org> wrote:
>
> On Thu, Nov 28, 2019 at 15:59:14 +0100, Ard Biesheuvel wrote:
> > On Thu, 28 Nov 2019 at 15:56, Leif Lindholm <leif.lindholm@linaro.org> wrote:
> > >
> > > On Thu, Nov 28, 2019 at 15:48:39 +0100, Ard Biesheuvel wrote:
> > > > We switched to cache coherent DMA for the NETSEC network controller ages
> > > > ago, but the platform driver that registers the non-discoverable device
> > > > currently does not reflect this change, which we haven't noticed since
> > > > the driver doesn't look at this flag.
> > >
> > > Should the drive look at this flag?
> > >
> >
> > The driver links against DmaLib, so it is either built for coherent
> > DMA only, or for non-coherent DMA only. This is different from the
> > eMMC on this platform, since it uses NonDiscoverablePciDeviceDxe,
> > which implements support for both coherent and non-coherent DMA in the
> > same driver, so there it has to be accurate or things break. For
> > NETSEC, we could add a check I suppose, but it is certainly not a high
> > prio thing imo.
>
> Ah, fair enough.
> Thanks for the explanation.
>

Series pushed as 6bde2876c3aa..8e75ee0c9653

Thanks,