Re: [PATCH 00/12] iommu: qcom_iommu: implement support for instances on MSM8974

[Luca Weiss]

Hi Dmitry,

Many thanks for working on this and sending this patch series!

On Sun Aug 9, 2026 at 10:15 PM CEST, Dmitry Baryshkov wrote:
> Qualcomm MSM8974 platform has five SMMU instances, used by display, GPU,
> Venus, VFE (camera) and JPEG encoder. Each of them follows ARM SMMU v1
> spec, however they differ from other Qualcomm platforms in the
> implementation-specific registers and also in interaction with TZ.
> Venus, MDP and VFE SMMUs are secured and require programming only of
> CBs, while GPU and JPEG require full programming.
>
> This series skips IOMMUs which can't be tested right now (VFE and JPEG),
> and adds only MDP, GPU and Venus (although untested, it is required for
> display to work) SMMU instances.

I do have a patch series (sent years ago to the mailing lists as well)
for CAMSS so I can definitely test this in the future.

>
> Note, to get display to work properly one fix is necessary, [1]
>
> [1] https://patch.msgid.link/20260809-msm8974-mmcc-fix-v1-1-50f2dcf18d2e@xxxxxxxxxxxxxxxx

I've applied this series on v7.2-rc7, with the extra commits between
that and linux-next for qcom_iommu.c backported so that your series
applies without conflicts.

So far I'm stuck with the GPU not being able to probe, adding some
printk's shows that in msm_iommu_new() the call for
iommu_attach_device() is failing.

[    5.971154] msm_mdp fd900100.display-controller: failed to load adreno gpu
[    5.972991] msm_mdp fd900100.display-controller: failed to bind fdb00000.gpu (ops a3xx_ops [msm]): -16
[    5.974073] msm_mdp fd900100.display-controller: adev bind failed: -16
[    5.974152] panel-s6d6fa1 fd922800.dsi.0: error -EBUSY: Failed to attach to DSI host
[    5.974230] panel-s6d6fa1 fd922800.dsi.0: probe with driver panel-s6d6fa1 failed with error -16

~ # dmesg | grep iommu
[    0.127014] iommu: Default domain type: Translated
[    0.127052] iommu: DMA domain TLB invalidation policy: strict mode
[    0.739899] platform fdb00000.gpu: Adding to iommu group 0
[    0.741358] qcom-iommu fdc84000.iommu: iommu sec: pgtable size: 90112
[    6.006877] platform fd900100.display-controller: Adding to iommu group 1

Have you seen any issues like this?

Regards
Luca

>
> Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@xxxxxxxxxxxxxxxx>
> ---
> Dmitry Baryshkov (12):
>       dt-bindings: iommu: qcom,iommu: document the MSM8974 IOMMUs
>       iommu: arm-smmu: add global register definitions used by the QSMMU
>       iommu: qcom_iommu: extract context bank programming into a helper
>       iommu: qcom_iommu: support the short-descriptor pagetable format
>       iommu: qcom_iommu: handle the SMMU global register space
>       iommu: qcom_iommu: support non-TZ-managed instances
>       iommu: qcom_iommu: restore context bank state after power collapse
>       iommu: qcom_iommu: halt the micro-MMU while programming context banks
>       iommu: qcom_iommu: allow faulting transactions to terminate
>       iommu: qcom_iommu: program BFP (prefetch) settings
>       iommu: qcom_iommu: add the MSM8974 instances
>       ARM: dts: qcom: msm8974: add the IOMMUs
>
>  .../devicetree/bindings/iommu/qcom,iommu.yaml      |  16 +-
>  arch/arm/boot/dts/qcom/qcom-msm8974.dtsi           |  85 +++-
>  drivers/iommu/arm/Kconfig                          |   1 +
>  drivers/iommu/arm/arm-smmu/arm-smmu.h              |  10 +
>  drivers/iommu/arm/arm-smmu/qcom_iommu.c            | 445 +++++++++++++++++++--
>  5 files changed, 517 insertions(+), 40 deletions(-)
> ---
> base-commit: 6c5c106bff878247a9cc7255077aab9040df8bf8
> change-id: 20260809-msm8974-iommu-upstream-144b1e2a15f0
>
> Best regards,
> --  
> With best wishes
> Dmitry