[PATCH 0/2] media: qcom: Fix iova allocation from restrict region

The VPU issues DMA through several SMMU streams, and the hardware does
not give every stream the same addressable range. The non-pixel stream
cannot address the low 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 restricts a
non-pixel buffer to avoid 0 to 600MB. 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

A series to reserve the 0-600MB IOVA range via "iommu-addresses" was
already posted here:
https://lore.kernel.org/all/[email protected]

Those changes involve DT binding and DT node changes, and discussion is
still ongoing on how to handle those for stable and for the upcoming
sub-node design, with no conclusion reached yet. Thereby a critical reset
issue is still open.

This is an alternate solution to fix the unhandled SMMU page fault
by restricting the IOVA range in the video driver, which also makes it
easier and faster to land on mainline and stable kernels.

Currently sub-nodes are not yet present, and only a single device is
available, so the restriction is applied to both non-pixel and pixel
stream IDs. This makes the solution unoptimal while fixing the issue
considering all scenarios.
Once sub-nodes for non-pixel, pixel, and secure streams become available,
the restriction can be made stream specific.

Signed-off-by: Vishnu Reddy <[email protected]>
---
Vishnu Reddy (2):
      media: iris: Fix iova allocation from restrict region
      media: venus: Fix iova allocation from restrict region

 drivers/media/platform/qcom/iris/iris_core.h  |  6 +++
 drivers/media/platform/qcom/iris/iris_probe.c | 69 +++++++++++++++++++++++++-
 drivers/media/platform/qcom/venus/core.c      | 71 ++++++++++++++++++++++++++-
 drivers/media/platform/qcom/venus/core.h      |  5 ++
 4 files changed, 148 insertions(+), 3 deletions(-)
---
base-commit: 5e6de6a2b522f659defacb1551d0465ba6ce13cf
change-id: 20260812-reserve_iova_in_driver-855b388cbb29

Best regards,
--  
Vishnu Reddy <[email protected]>