From fbe5d36e7789827704b8f15cd99971f2615c0832 Mon Sep 17 00:00:00 2001
From: Ben Widawsky <benjamin.widawsky@intel.com>
Date: Mon, 4 Nov 2013 19:56:49 -0800
Subject: [PATCH] drm/i915/bdw: Support BDW caching
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BDW caching works differently than the previous generations. Instead of
having bits in the PTE which directly control how the page is cached,
the 3 PTE bits PWT PCD and PAT provide an index into a PAT defined by
register 0x40e0. This style of caching is functionally equivalent to how
it works on HSW and before.

v2: Tiny bikeshed as discussed on internal irc.

v3: Squash in patch from Ville to mirror the x86 PAT setup more like
in arch/x86/mm/pat.c. Primarily, the 0th index will be WB, and not
uncached.

v4: Comment for reason to not use a 64b write on the PPAT.

v5: Add a FIXME comment that the caching bits in the PAT registers
might be wrong due to doc confusion.

Cc: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Ben Widawsky <ben@bwidawsk.net> (v1)
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Imre Deak <imre.deak@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
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