On Wednesday, March 25, 2020 9:50 AM, Neil Armstrong [off-list ref] wrote:

Amlogic uses a proprietary lossless image compression protocol and format
for their hardware video codec accelerators, either video decoders or
video input encoders.

This introduces the Scatter Memory layout, means the header contains IOMMU
references to the compressed frames content to optimize memory access
and layout.

In this mode, only the header memory address is needed, thus the content
memory organization is tied to the current producer execution and cannot
be saved/dumped neither transferrable between Amlogic SoCs supporting this
modifier.

I don't think this is suitable for modifiers. User-space relies on
being able to copy a buffer from one machine to another over the
network. It would be pretty annoying for user-space to have a blacklist
of modifiers that don't work this way.

Example of such user-space:
https://gitlab.freedesktop.org/mstoeckl/waypipe/

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