[PATCH 2/2] drm/vram-helper: Alternate between bottom-up and top-down placement

[Gerd Hoffmann]

  Hi,

> At some point one has to choose to switch to top-down, and then back
> again at one of the next BOs. So the current patch effectively splits
> vram into a lower half and an upper half and puts BOs in alternating halves.

Hmm, so maybe just make the split explicit instead of playing tricks
with top_bottom?  Register the lower vram half as TT_VRAM, register the
upper half as TT_PRIV.  That'll make sure you never have a big
allocation in the middle blocking things.  Or maybe add a allocation
strategy flag to ttm which effectively does the same.

take care,
  Gerd