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From:   Linus Torvalds <torvalds@linux-foundation.org>
Date:   Wed, 21 Sep 2022 09:24:29 -0700
Message-ID: <CAHk-=whdwG2LaaktZTYab2JO2TkPYEmSc-sOJ=qL5wtOWpRpKA@mail.gmail.com>
Subject: Re: [PATCH v2] iommu: Optimise PCI SAC address trick
To:     Robin Murphy <robin.murphy@arm.com>
Cc:     joro@8bytes.org, will@kernel.org, iommu@lists.linux.dev,
        linux-kernel@vger.kernel.org
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On Wed, Sep 21, 2022 at 5:53 AM Robin Murphy <robin.murphy@arm.com> wrote:
>
> Per the reasoning in commit 4bf7fda4dce2 ("iommu/dma: Add config for
> PCI SAC address trick") and its subsequent revert, this mechanism no
> longer serves its original purpose, but now only works around broken
> hardware/drivers in a way that is unfortunately too impactful to remove.

I was going to test this, since the previous version failed for me.
But it's based on linux-next, and I didn't want to fight the conflicts
(including - but not limited to - the header file being moved) so I
dropped that plan.

If you think it's worth testing on the setup that used to fail, and
you send me a version that applies on my current tree, I can do so.

               Linus