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From:   Oded Gabbay <ogabbay@kernel.org>
Date:   Mon, 30 Jan 2023 16:22:05 +0200
Message-ID: <CAFCwf135w+iVn2qiucNrgig+cj=+kQiSUwxMcBPVYVPp-doE5Q@mail.gmail.com>
Subject: Re: [PATCH 1/8] iommu: Decouple iommu_present() from bus ops
To:     Jason Gunthorpe <jgg@nvidia.com>
Cc:     Robin Murphy <robin.murphy@arm.com>,
        Baolu Lu <baolu.lu@linux.intel.com>, joro@8bytes.org,
        will@kernel.org, hch@lst.de, iommu@lists.linux.dev,
        linux-kernel@vger.kernel.org
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On Mon, Jan 30, 2023 at 3:53 PM Jason Gunthorpe <jgg@nvidia.com> wrote:
>
> On Mon, Jan 30, 2023 at 01:49:20PM +0000, Robin Murphy wrote:
>
> > All in all, it's only actually the habanalabs ones that I'm slightly wary
> > of, since they're effectively (mis)using device_iommu_mapped() to infer the
> > DMA ops implementation, which could potentially go wrong (or at least *more*
> > wrong) on POWER with this change. I guess the saving grace is that
> > although
>
> IMHO habana is not using the DMA API abstraction properly. If it
> doesn't work on some archs is their bugs to deal with - we don't need
> to complexify the core code to tiptoe around around such an abuse in
> an obscure driver.
>
> Jason
Agreed, feel free to change the kapi as you see fit. Do the right
thing for the kernel.
In any case, we limit ourselves to x86-64 arch in the 6.3 merge cycle.

Oded