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Amlogic uses a proprietary lossless image compression protocol and format for their hardware video codec accelerators, either video decoders or video input encoders. It considerably reduces memory bandwidth while writing and reading frames in memory. The underlying storage is considered to be 3 components, 8bit or 10-bit per component, YCbCr 420, single plane : - DRM_FORMAT_YUV420_8BIT - DRM_FORMAT_YUV420_10BIT This modifier will be notably added to DMA-BUF frames imported from the V4L2 Amlogic VDEC decoder. This introduces the basic layout composed of: - a body content organized in 64x32 superblocks with 4096 bytes per superblock in default mode. - a 32 bytes per 128x64 header block This layout is tranferrable between Amlogic SoCs supporting this modifier. The Memory Saving option exist changing the layout superblock size to save memory when using 8bit components pixels size. Finally is also adds the Scatter Memory layout, meaning 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. Signed-off-by: Neil Armstrong <narmstrong@baylibre.com> Tested-by: Kevin Hilman <khilman@baylibre.com> Reviewed-by: Kevin Hilman <khilman@baylibre.com> Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch> Link: https://patchwork.freedesktop.org/patch/msgid/20200703080728.25207-2-narmstrong@baylibre.com |
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