Re: [PATCH v3 3/4] iommu/arm-smmu: Add support to handle Qcom's wait-for-safe logic

From: Vivek Gautam <vivek.gautam@codeaurora.org>
To: Will Deacon <will@kernel.org>
Cc: "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
	<devicetree@vger.kernel.org>,
	linux-arm-msm <linux-arm-msm@vger.kernel.org>,
	Will Deacon <will.deacon@arm.com>,
	open list <linux-kernel@vger.kernel.org>,
	Bjorn Andersson <bjorn.andersson@linaro.org>,
	David Brown <david.brown@linaro.org>,
	"list@263.net:IOMMU DRIVERS <iommu@lists.linux-foundation.org>,
	Joerg Roedel <joro@8bytes.org>,"
	<iommu@lists.linux-foundation.org>,
	"robh+dt" <robh+dt@kernel.org>, Andy Gross <agross@kernel.org>,
	Robin Murphy <robin.murphy@arm.com>,
	Rob Clark <robdclark@gmail.com>
Subject: Re: [PATCH v3 3/4] iommu/arm-smmu: Add support to handle Qcom's wait-for-safe logic
Date: Thu, 27 Jun 2019 12:35:02 +0530	[thread overview]
Message-ID: <CAFp+6iGvUd6QhmEO0rSSXAZnYt3x_5G0HuGUJYZ203W1_ER+=w@mail.gmail.com> (raw)
In-Reply-To: <20190626144844.key3n6ueb6skgkp4@willie-the-truck>

On Wed, Jun 26, 2019 at 8:18 PM Will Deacon <will@kernel.org> wrote:
>
> On Wed, Jun 26, 2019 at 12:03:02PM +0530, Vivek Gautam wrote:
> > On Tue, Jun 25, 2019 at 7:09 PM Will Deacon <will@kernel.org> wrote:
> > >
> > > On Tue, Jun 25, 2019 at 12:34:56PM +0530, Vivek Gautam wrote:
> > > > On Mon, Jun 24, 2019 at 10:33 PM Will Deacon <will@kernel.org> wrote:
> > > > > Instead, I think this needs to be part of a separate file that is maintained
> > > > > by you, which follows on from the work that Krishna is doing for nvidia
> > > > > built on top of Robin's prototype patches:
> > > > >
> > > > > http://linux-arm.org/git?p=linux-rm.git;a=shortlog;h=refs/heads/iommu/smmu-impl
> > > >
> > > > Looking at this branch quickly, it seem there can be separate implementation
> > > > level configuration file that can be added.
> > > > But will this also handle separate page table ops when required in future.
> > >
> > > Nothing's set in stone, but having the implementation-specific code
> > > constrain the page-table format (especially wrt quirks) sounds reasonable to
> > > me. I'm currently waiting for Krishna to respin the nvidia changes [1] on
> > > top of this so that we can see how well the abstractions are holding up.
> >
> > Sure. Would you want me to try Robin's branch and take out the qualcomm
> > related stuff to its own implementation? Or, would you like me to respin this
> > series so that you can take it in to enable SDM845 boards such as, MTP
> > and dragonboard to have a sane build - debian, etc. so people benefit
> > out of it.
>
> I can't take this series without Acks on the firmware calling changes, and I
> plan to send my 5.3 patches to Joerg at the end of the week so they get some
> time in -next. In which case, I think it may be worth you having a play with
> the branch above so we can get a better idea of any additional smmu_impl hooks
> you may need.

Cool. I will play around with it and get something tangible and meaningful.

>
> > Qualcomm stuff is lying in qcom-smmu and arm-smmu and may take some
> > time to stub out the implementation related details.
>
> Not sure I follow you here. Are you talking about qcom_iommu.c?

That's right. The qcom_iommu.c solved a different issue of secure context bank
allocations, when Rob forked out this driver and reused some of the
arm-smmu.c stuff.

We will take a look at that once we start adding the qcom implementation.

Thanks
Vivek

>
> Will
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> iommu mailing list
> iommu@lists.linux-foundation.org
> https://lists.linuxfoundation.org/mailman/listinfo/iommu

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