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Commit 9e984bc1 authored by Adam Jackson's avatar Adam Jackson Committed by Daniel Vetter
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drm/i915: Don't do MTRR setup if PAT is enabled 



Some newer BIOSes are shipping with all MTRRs already populated.  These
BIOSes are all on machines with sufficiently new CPUs that the
referenced errata doesn't apply anyway, so just don't try to claim the
MTRR.

Signed-off-by: default avatarAdam Jackson <ajax@redhat.com>
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=41648


Signed-off-by: default avatarDaniel Vetter <daniel.vetter@ffwll.ch>
parent e2b665c4

drivers/gpu/drm/i915/i915_dma.c

+6 −0
Original line number Diff line number Diff line
@@ -43,6 +43,7 @@ 
#include <linux/slab.h>

#include <linux/module.h>

#include <acpi/video.h>

#include <asm/pat.h>



static void i915_write_hws_pga(struct drm_device *dev)

{
@@ -1918,6 +1919,11 @@ static void 
i915_mtrr_setup(struct drm_i915_private *dev_priv, unsigned long base,

		unsigned long size)

{

#if defined(CONFIG_X86_PAT)

	if (cpu_has_pat)

		return;

#endif



	/* Set up a WC MTRR for non-PAT systems.  This is more common than

	 * one would think, because the kernel disables PAT on first

	 * generation Core chips because WC PAT gets overridden by a UC