linux-kernel - Re: [PATCH 1/2] arm64: dts: qcom: agatti: Fix IOMMU DT properties

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Message-ID: <aVygxoQ-vaKd4An6@sumit-xelite>
Date: Tue, 6 Jan 2026 11:12:30 +0530
From: Sumit Garg <sumit.garg@...nel.org>
To: Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>
Cc: Vikash Garodia <vikash.garodia@....qualcomm.com>,
	Sumit Garg <sumit.garg@....qualcomm.com>,
	linux-arm-msm@...r.kernel.org, devicetree@...r.kernel.org,
	andersson@...nel.org, konradybcio@...nel.org, robh@...nel.org,
	krzk+dt@...nel.org, conor+dt@...nel.org, akhilpo@....qualcomm.com,
	dikshita.agarwal@....qualcomm.com, robin.clark@....qualcomm.com,
	lumag@...nel.org, linux-kernel@...r.kernel.org,
	Prakash Gupta <guptap@....qualcomm.com>
Subject: Re: [PATCH 1/2] arm64: dts: qcom: agatti: Fix IOMMU DT properties

On Tue, Jan 06, 2026 at 04:38:43AM +0200, Dmitry Baryshkov wrote:
> On Mon, Jan 05, 2026 at 12:51:09PM +0530, Vikash Garodia wrote:
> > Hi Sumit,
> > 
> > On 1/2/2026 5:22 PM, Sumit Garg wrote:
> > > On Fri, Jan 02, 2026 at 03:32:57PM +0530, Vikash Garodia wrote:
> > > > 
> > > > On 12/29/2025 12:50 PM, Sumit Garg wrote:
> > > > > Hey Everyone,
> > > > > 
> > > > > On Mon, Dec 29, 2025 at 12:37 PM Sumit Garg <sumit.garg@....qualcomm.com> wrote:
> > > > > > 
> > > > > > Fix IOMMU DT propeties for GPU, display and video peripherals via
> > > > > > dropping SMMU stream IDs which relates to secure context bank.
> > > > > > 
> > > > > > This problem only surfaced when the Gunyah based firmware stack is
> > > > > > ported on Agatti replacing the legacy QHEE based firmware stack. Assigning
> > > > > > Linux kernel (HLOS) VMID to secure context bank stream IDs is treated
> > > > > > as a fault by Gunyah hypervisor which were previously ignored by QHEE
> > > > > > hypervisor.
> > > > > > 
> > > > > > The DT changes should be backwards compatible with legacy QHEE based
> > > > > > firmware stack too.
> > > > > > 
> > > > > > Suggested-by: Prakash Gupta <guptap@....qualcomm.com>
> > > > > > Signed-off-by: Sumit Garg <sumit.garg@....qualcomm.com>
> > > > > > ---
> > > > > >    arch/arm64/boot/dts/qcom/agatti.dtsi | 11 +++--------
> > > > > >    1 file changed, 3 insertions(+), 8 deletions(-)
> > > > > > 
> > > > > 
> > > > > Looks like I messed up this patch-set with email delivery leading to
> > > > > non-delivery. I resent it properly again here [1]. Apologies for the
> > > > > noise.
> > > > > 
> > > > > [1] https://lore.kernel.org/lkml/20251229070712.456138-1-sumit.garg@oss.qualcomm.com/
> > > > > 
> > > > > -Sumit
> > > > > 
> > > > > > diff --git a/arch/arm64/boot/dts/qcom/agatti.dtsi b/arch/arm64/boot/dts/qcom/agatti.dtsi
> > > > > > index 8bf5c5583fc2..e705eb24160a 100644
> > > > > > --- a/arch/arm64/boot/dts/qcom/agatti.dtsi
> > > > > > +++ b/arch/arm64/boot/dts/qcom/agatti.dtsi
> > > > > > @@ -1613,8 +1613,7 @@ gpu: gpu@...0000 {
> > > > > >                                            &bimc SLAVE_EBI1 RPM_ALWAYS_TAG>;
> > > > > >                           interconnect-names = "gfx-mem";
> > > > > > 
> > > > > > -                       iommus = <&adreno_smmu 0 1>,
> > > > > > -                                <&adreno_smmu 2 0>;
> > > > > > +                       iommus = <&adreno_smmu 0 1>;
> > > > > >                           operating-points-v2 = <&gpu_opp_table>;
> > > > > >                           power-domains = <&rpmpd QCM2290_VDDCX>;
> > > > > >                           qcom,gmu = <&gmu_wrapper>;
> > > > > > @@ -1895,8 +1894,7 @@ mdss: display-subsystem@...0000 {
> > > > > > 
> > > > > >                           power-domains = <&dispcc MDSS_GDSC>;
> > > > > > 
> > > > > > -                       iommus = <&apps_smmu 0x420 0x2>,
> > > > > > -                                <&apps_smmu 0x421 0x0>;
> > > > > > +                       iommus = <&apps_smmu 0x420 0x2>;
> > > > > >                           interconnects = <&mmrt_virt MASTER_MDP0 RPM_ALWAYS_TAG
> > > > > >                                            &bimc SLAVE_EBI1 RPM_ALWAYS_TAG>,
> > > > > >                                           <&bimc MASTER_APPSS_PROC RPM_ALWAYS_TAG
> > > > > > @@ -2339,10 +2337,7 @@ venus: video-codec@...0000 {
> > > > > > 
> > > > > >                           memory-region = <&pil_video_mem>;
> > > > > >                           iommus = <&apps_smmu 0x860 0x0>,
> > > > > > -                                <&apps_smmu 0x880 0x0>,
> > > > > > -                                <&apps_smmu 0x861 0x04>,
> > > > > > -                                <&apps_smmu 0x863 0x0>,
> > > > > > -                                <&apps_smmu 0x804 0xe0>;
> > > > > > +                                <&apps_smmu 0x880 0x0>;
> > > > 
> > > > Are you planning to update the binding [1] with this change ?
> > > 
> > > Yeah I am planning to update bindings as per changes posted here [1].
> > 
> > I tried a similar approach for the very same usecase [1], and what i learnt
> > is that we cannot describe a range of iommus given the fact that there is no
> > hardware which exist with *min* count of iommus interface. It is suppose to
> > be a fixed number of iommus interface, OR i interpreted it differently then
> > ?
> 
> You've interpreted it correctly. Sumit will need to drop the extra items
> from the corresponding iommus property definition.

Thanks for the heads up. I will follow this advice instead.

-Sumit