From: Jordan Crouse <jcrouse@codeaurora.org>
To: freedreno@lists.freedesktop.org
Cc: Rob Herring <robh@kernel.org>,
jean-philippe.brucker@arm.com, linux-arm-msm@vger.kernel.org,
Joerg Roedel <joro@8bytes.org>,
linux-kernel@vger.kernel.org, iommu@lists.linux-foundation.org,
Zhen Lei <thunder.leizhen@huawei.com>,
Will Deacon <will@kernel.org>,
linux-arm-kernel@lists.infradead.org, robin.murphy@arm.com
Subject: Re: [Freedreno] [PATCH v3 0/2] iommu/arm-smmu: Split pagetable support
Date: Thu, 15 Aug 2019 09:33:04 -0600 [thread overview]
Message-ID: <20190815153304.GD28465@jcrouse1-lnx.qualcomm.com> (raw)
In-Reply-To: <1565216500-28506-1-git-send-email-jcrouse@codeaurora.org>
On Wed, Aug 07, 2019 at 04:21:38PM -0600, Jordan Crouse wrote:
> (Sigh, resend. I freaked out my SMTP server)
>
> This is part of an ongoing evolution for enabling split pagetable support for
> arm-smmu. Previous versions can be found [1].
>
> In the discussion for v2 Robin pointed out that this is a very Adreno specific
> use case and that is exactly true. Not only do we want to configure and use a
> pagetable in the TTBR1 space, we also want to configure the TTBR0 region but
> not allocate a pagetable for it or touch it until the GPU hardware does so. As
> much as I want it to be a generic concept it really isn't.
>
> This revision leans into that idea. Most of the same io-pgtable code is there
> but now it is wrapped as an Adreno GPU specific format that is selected by the
> compatible string in the arm-smmu device.
>
> Additionally, per Robin's suggestion we are skipping creating a TTBR0 pagetable
> to save on wasted memory.
>
> This isn't as clean as I would like it to be but I think that this is a better
> direction than trying to pretend that the generic format would work.
>
> I'm tempting fate by posting this and then taking some time off, but I wanted
> to try to kick off a conversation or at least get some flames so I can try to
> refine this again next week. Please take a look and give some advice on the
> direction.
Will, Robin -
Modulo the impl changes from Robin, do you think that using a dedicated
pagetable format is the right approach for supporting split pagetables for the
Adreno GPU?
If so, then is adding the changes to io-pgtable-arm.c possible for 5.4 and then
add the implementation specific code on top of Robin's stack later or do you
feel they should come as part of a package deal?
Jordan
> Jordan Crouse (2):
> iommu/io-pgtable-arm: Add support for ARM_ADRENO_GPU_LPAE io-pgtable
> format
> iommu/arm-smmu: Add support for Adreno GPU pagetable formats
>
> drivers/iommu/arm-smmu.c | 8 +-
> drivers/iommu/io-pgtable-arm.c | 214 ++++++++++++++++++++++++++++++++++++++---
> drivers/iommu/io-pgtable.c | 1 +
> include/linux/io-pgtable.h | 2 +
> 4 files changed, 209 insertions(+), 16 deletions(-)
>
> --
> 2.7.4
>
> _______________________________________________
> Freedreno mailing list
> Freedreno@lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/freedreno
--
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a Linux Foundation Collaborative Project
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next prev parent reply other threads:[~2019-08-15 15:33 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-07 22:21 [PATCH v3 0/2] iommu/arm-smmu: Split pagetable support Jordan Crouse
2019-08-07 22:21 ` [PATCH v3 1/2] iommu/io-pgtable-arm: Add support for ARM_ADRENO_GPU_LPAE io-pgtable format Jordan Crouse
2019-08-15 15:35 ` Jordan Crouse
2019-08-07 22:21 ` [PATCH v3 2/2] iommu/arm-smmu: Add support for Adreno GPU pagetable formats Jordan Crouse
2019-08-15 15:33 ` Jordan Crouse [this message]
2019-08-16 16:58 ` [Freedreno] [PATCH v3 0/2] iommu/arm-smmu: Split pagetable support Robin Murphy
2019-08-16 18:12 ` Rob Clark
2019-08-16 19:43 ` Robin Murphy
2019-08-16 22:20 ` Jordan Crouse
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