• Thierry Reding's avatar
    gpu: host1x: Introduce support for wide opcodes · 5a5fccbd
    Thierry Reding authored
    The CDMA push buffer can currently only handle opcodes that take a
    single word parameter. However, the host1x implementation on Tegra186
    and later supports opcodes that require multiple words as parameters.
    
    Unfortunately the way the push buffer is structured, these wide opcodes
    cannot simply be composed of two regular opcodes because that could
    result in the wide opcode being split across the end of the push buffer
    and the final RESTART opcode required to wrap the push buffer around
    would break the wide opcode.
    
    One way to fix this would be to remove the concept of slots to simplify
    push buffer operations. However, that's not entirely trivial and should
    be done in a separate patch. For now, simply use a different function
    to push four-word opcodes into the push buffer. Technically only three
    words are pushed, with the fourth word used as padding to preserve the
    2-word alignment required by the slots abstraction. The fourth word is
    always a NOP opcode.
    
    Additional care must be taken when the end of the push buffer is
    reached. If a four-word opcode doesn't fit into the push buffer without
    being split by the boundary, NOP opcodes will be introduced and the new
    wide opcode placed at the beginning of the push buffer.
    Signed-off-by: default avatarThierry Reding <treding@nvidia.com>
    5a5fccbd