Re: [Freedreno] [PATCH v7 6/6] arm6: dts: qcom: sm845: Set the compatible string for the GPU SMMU

From: Jordan Crouse <jcrouse@codeaurora.org>
To: Rob Clark <robdclark@gmail.com>
Cc: "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
	<devicetree@vger.kernel.org>,
	linux-arm-msm <linux-arm-msm@vger.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Rob Herring <robh+dt@kernel.org>,
	Bjorn Andersson <bjorn.andersson@linaro.org>,
	Andy Gross <agross@kernel.org>,
	freedreno <freedreno@lists.freedesktop.org>
Subject: Re: [Freedreno] [PATCH v7 6/6] arm6: dts: qcom: sm845: Set the compatible string for the GPU SMMU
Date: Thu, 4 Jun 2020 16:47:29 -0600	[thread overview]
Message-ID: <20200604224729.GB12322@jcrouse1-lnx.qualcomm.com> (raw)
In-Reply-To: <CAF6AEGssC5ZJKh3oMR6fFRJwZvWLy4YjE2anvq5sDmPB_ikv0Q@mail.gmail.com>

On Thu, Jun 04, 2020 at 03:38:28PM -0700, Rob Clark wrote:
> On Thu, Jun 4, 2020 at 3:02 PM Jordan Crouse <jcrouse@codeaurora.org> wrote:
> >
> > On Thu, Jun 04, 2020 at 02:27:21PM -0700, Rob Clark wrote:
> > > On Thu, Jun 4, 2020 at 1:57 PM Jordan Crouse <jcrouse@codeaurora.org> wrote:
> > > >
> > > > Set the qcom,adreno-smmu compatible string for the GPU SMMU to enable
> > > > split pagetables.
> > > >
> > > > Signed-off-by: Jordan Crouse <jcrouse@codeaurora.org>
> > > > ---
> > > >
> > > >  arch/arm64/boot/dts/qcom/sdm845.dtsi | 2 +-
> > > >  1 file changed, 1 insertion(+), 1 deletion(-)
> > > >
> > > > diff --git a/arch/arm64/boot/dts/qcom/sdm845.dtsi b/arch/arm64/boot/dts/qcom/sdm845.dtsi
> > > > index 8eb5a31346d2..8b15cd74e9ba 100644
> > > > --- a/arch/arm64/boot/dts/qcom/sdm845.dtsi
> > > > +++ b/arch/arm64/boot/dts/qcom/sdm845.dtsi
> > > > @@ -3556,7 +3556,7 @@
> > > >                 };
> > > >
> > > >                 adreno_smmu: iommu@5040000 {
> > > > -                       compatible = "qcom,sdm845-smmu-v2", "qcom,smmu-v2";
> > > > +                       compatible = "qcom,adreno-smmu", "qcom,smmu-v2";
> > >
> > > Should this be something like:
> > >
> > >    compatible = "qcom,adreno-smmu", "qcom,sdm845-smmu-v2", "qcom,smmu-v2";
> > >
> > > so that new dtb still works with old kernel?
> >
> > As far as I know qcom,sdm845-smmu-v2 never was actually used unless we were
> > doing the parsing trick somewhere.
> 
> I *think* it has a use queued up for v5.8 for the
> select-direct-mapping stuff?  I'm not 100% sure of the status of that
> off the top of my head.

That uses the compatible string of the consumer device.  I can add
it back in but I didn't think we needed to complicate the bindings any more if
we didn't have to.

Jordan

> BR,
> -R
> 
> > Jordan
> >
> > > >                         reg = <0 0x5040000 0 0x10000>;
> > > >                         #iommu-cells = <1>;
> > > >                         #global-interrupts = <2>;
> > > > --
> > > > 2.17.1
> > > >
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> >
> > --
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> > a Linux Foundation Collaborative Project
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