[Intel-gfx] [PATCH 3/4] drm/i915/gtt/xehpsdv: move scratch page to system memory

[Andi Shyti]

Hi Ram and Matt,

> On some platforms the hw has dropped support for 4K GTT pages when
> dealing with LMEM, and due to the design of 64K GTT pages in the hw, we
> can only mark the *entire* page-table as operating in 64K GTT mode,
> since the enable bit is still on the pde, and not the pte. And since we
> we still need to allow 4K GTT pages for SMEM objects, we can't have a
> "normal" 4K page-table with scratch pointing to LMEM, since that's
> undefined from the hw pov. The simplest solution is to just move the 64K
> scratch page to SMEM on such platforms and call it a day, since that
> should work for all configurations.
> 
> Signed-off-by: Matthew Auld <matthew.auld at intel.com>
> Signed-off-by: Ramalingam C <ramalingam.c at intel.com>
> Reviewed-by: Thomas Hellstrom <thomas.hellstrom at linux.intel.com>

Reviewed-by: Andi Shyti <andi.shyti at linux.intel.com>

Andi