[PATCH v3 00/13] media: iris: Migrate iommus to iris sub nodes

The VPU issues DMA through several SMMU streams, and the hardware does 
not restricts specific streams with specific addressable range. The 
non-pixel stream is restricted to use 0-600MB of IOVA space, while the 
pixel stream can address the full range:
    +-----------------------------------------------------------+
    | non-pixel stream addressable range (600 MB - 3.5 GB)      |
    | 0x25800000 - 0xe0000000                                   |
    +-----------------------------------------------------------+
    | pixel stream addressable range (0 - 3.5 GB)               |
    | 0x00000000 - 0xe0000000                                   |
    +-----------------------------------------------------------+

A single "iommus" property on the video-codec node puts every stream in
one IOMMU domain sharing one IOVA allocator, so nothing keeps a
non-pixel buffer inside the low 600 MB. Once an allocation lands below
that boundary the hardware faults, which shows up as unhandled SMMU page
faults and spontaneous reboots:
https://gitlab.freedesktop.org/drm/msm/-/work_items/100

Fix was made in iris/venus driver to reserve the 0-600MB range and 
thereby prevent iova allocation from that range. 
https://lore.kernel.org/all/20260818-reserve_iova_in_driver-v2-0-5005a1154408@oss.qualcomm.com (local)

Given that the address range restriction is for specific VPU stream, it 
should be ideally moved to that stream. To achieve the same, a subset 
of streams is now represented as subnodes, so that each can be 
associated with its respective addressable range.

In the past, this limitation was addressed with an iommu-map approach,
with the iris driver dynamically creating the devices. That approach
was later concluded to be a hack to avoid having subnodes, and was NAKed
by the iommu maintainers. It was discussed in detail here:
https://lore.kernel.org/all/c7b956a9-d3e8-4e18-b780-5d08f5cd2ca1@kernel.org/ (local)

The maintainers agreed to proceed with the subnode approach to address
the VPU hardware limitation.

Reserving the iova address using "iommu-addresses" requires it to be 
placed in the reserved-memory node. But when "iommu-addresses" is the 
*only* property being described and there is no backing "reg" (i.e. no
actual reserved system memory), it does not really belong to 
reserved-memory node. A device IOVA range is very much specific to the 
way device own address space is mapped, and not a description of memory
shared across the system. Given this, "iommu-addresses" backed by a 
"reg", should be placed inside reserved-memory, otherwise, it should be 
defined within the device node. More info on this discussion can be 
found at
https://lore.kernel.org/all/662f7093-fb0a-4564-9ca0-98e03e68ba9a@kernel.org (local)

"iommu-addresses" property expects a phandle, which does not make sense 
when the same is defined within individual device node itself. 
Introduced a new property, "iommu-ranges", for the IOVA ranges required 
for DMA memory mapping to that device node and when there is no physical 
memory reservation.

"iommu-ranges" is defined with the schema PR
https://github.com/devicetree-org/dt-schema/pull/207

This series migrate vpu3x platforms to subnodes. All new SOC having 
iris3x or onwards(4x 5x..) should follow the subnode approach.
For VPU2x and AR50Lite SOCs, which are being migrated to iris, the 
subnode support would be added once the SOC is migrated away from venus 
to iris. There is no plan to upgrade venus enabled SOC to subnodes.

Signed-off-by: Vikash Garodia <vikash.garodia@oss.qualcomm.com>
---
Changes in v3:
- Drop iommu-addresses from reserved memory (Rob)
- Defined a new property iommu-ranges (Krzysztof, Dmitry)
- Moved the vpu specific context bank handling to common(Dmitry)
- Dropped fixes tag.
- Link to v2: https://lore.kernel.org/r/20260731-vpu_iommu_iova_handling-v2-0-da52b5228dbd@oss.qualcomm.com (local)

Changes in v2:
- Fixed sashiko issues.
- Moved subnodes into common schema (Dmitry)
- Kept the firmware name as the one defained earlier (Dmitry)
- Added dma-ranges to specify parent-child address translation
- Moved context bank hooks to VPU ops (Dmitry)
- Updated commit description.
- Link to v1: https://lore.kernel.org/r/20260709-vpu_iommu_iova_handling-v1-0-72bb62cb2dfd@oss.qualcomm.com (local)

---
Vikash Garodia (13):
      dt-bindings: media: qcom,venus: Add context bank subnodes to common schema
      dt-bindings: media: qcom,sm8550-iris: Add context bank subnodes
      dt-bindings: media: qcom,sm8750-iris: Add context bank subnodes
      iommu: of_iommu: Add support for "iommu-ranges" on a device node
      media: iris: Add non-pixel and pixel context bank devices
      media: iris: Route buffers to the matching context bank device
      media: iris: Skip DMA mask setup when the core device has no IOMMU
      arm64: dts: qcom: hamoa: Add Iris context bank subnodes
      arm64: dts: qcom: sm8550: Add Iris context bank subnodes
      arm64: dts: qcom: lemans: Add Iris context bank subnodes
      arm64: dts: qcom: monaco: Add Iris context bank subnodes
      arm64: dts: qcom: sm8650: Add Iris context bank subnodes
      arm64: dts: qcom: sm8750: Add Iris context bank subnodes

 .../bindings/media/qcom,sc7180-venus.yaml          |  15 --
 .../bindings/media/qcom,sm8550-iris.yaml           | 118 +++++++------
 .../bindings/media/qcom,sm8750-iris.yaml           | 187 +++++++++++----------
 .../bindings/media/qcom,venus-common.yaml          |  97 +++++++++++
 arch/arm64/boot/dts/qcom/hamoa.dtsi                |  15 +-
 arch/arm64/boot/dts/qcom/lemans.dtsi               |  15 +-
 arch/arm64/boot/dts/qcom/monaco.dtsi               |  15 +-
 arch/arm64/boot/dts/qcom/sm8550.dtsi               |  15 +-
 arch/arm64/boot/dts/qcom/sm8650.dtsi               |  16 +-
 arch/arm64/boot/dts/qcom/sm8750.dtsi               |  15 +-
 drivers/iommu/of_iommu.c                           | 107 +++++++++++-
 drivers/media/platform/qcom/iris/iris_buffer.c     |   8 +-
 drivers/media/platform/qcom/iris/iris_core.h       |   4 +
 drivers/media/platform/qcom/iris/iris_hfi_queue.c  |  16 +-
 drivers/media/platform/qcom/iris/iris_probe.c      |  79 ++++++++-
 drivers/media/platform/qcom/iris/iris_resources.c  |  41 +++++
 drivers/media/platform/qcom/iris/iris_resources.h  |   1 +
 drivers/media/platform/qcom/iris/iris_vidc.c       |   4 +-
 18 files changed, 579 insertions(+), 189 deletions(-)
---
base-commit: a9d7ced84989ec05be09b4b8428759ef60450a0f
change-id: 20260701-vpu_iommu_iova_handling-556e969a1f1c

Best regards,
-- 
Vikash Garodia [off-list ref]