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

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@oss.qualcomm.com

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 <redacted>
---
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