AMD GFX12 modifiers

[Simon Ser]

Hi all!

In 7ceb94e87bff ("drm/amd: Add gfx12 swizzle mode defs"), some
definitions were added for GFX12 modifiers. However I'm not quite sure
I understand how these work.

Tile values seem to not be in the same namespace as GFX9 through GFX11,
is that correct? In other words, can GFX9 ~ GFX11 modifiers be used with
GFX12, or are these mutually exclusive?

AMD_FMT_MOD_GFX12_DCC_MAX_COMPRESSED_BLOCK_MASK has a comment explaining
the 3 possible values, is there a reason why #defines are missing for
these values?

The comment lists a lot more swizzle modes than just 64K_2D and 256K_2D,
any reason why the rest are missing (at least for the 2D ones)?

Could you explain how the new GFX12 modifiers work?

Would it be possible to update the comment on top of #define AMD_FMT_MOD
to reflect the GFX12 updates?

Thanks,

Simon