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

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Message-ID: <bf62a6aa-fba7-4c95-b1e4-9da2528d0556@oss.qualcomm.com>
Date: Mon, 5 Jan 2026 12:51:09 +0530
From: Vikash Garodia <vikash.garodia@....qualcomm.com>
To: Sumit Garg <sumit.garg@...nel.org>
Cc: 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

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 ?

[1] 
https://lore.kernel.org/all/20251017-knp_video-v2-1-f568ce1a4be3@oss.qualcomm.com/

> 
>> If so, how to
>> handle the case of iommus for gunyah based vs non-gunyah based ?
> 
> Currently Agatti doesn't have any support for Linux running in EL2. This
> patch-set is just trying to enable Gunyah based stack.
> 
> [1] https://lore.kernel.org/all/aVOFL3jmNrFNiYV0@sumit-xelite/
> 
> -Sumit