[PATCH] drm: Generalized NV Block Linear DRM format mod

[James Jones]

Beyond general review, I'm looking for feedback on a few things
specifically here:

-Is the level of backwards compatibility described here sufficient?
 Technically I can make the user space drivers support the old
 modifiers too, but that would mean the layout they specify would
 morph based on the GPU they're being used on, and sharing buffers
 between two different NV GPUs, which would appear to be possible,
 would result in corruption on one side or the other.

-I used "magic" numbers for all the bit shifting.  Would it be
 better to use __fourcc_XXX constants like the broadcom modifiers
 do?  I wasn't sure which style was preferred.  The nouveau code is
 full of magic numbers, but that's a bit lower level than this file.

If preferred, I can send this out as part of a patchset that adds
support for the modifiers to nouveau and TegraDRM, but I have some
things to clean up there before it's ready for proper review, and
I didn't want to block review of the basic modifier layout on that
work.