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Commit a53fa438 authored by Michel Dänzer's avatar Michel Dänzer Committed by Alex Deucher
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drm/radeon: Don't try to enable write-combining without PAT 

Doing so can cause things to become slow.

Print a warning at compile time and an informative message at runtime in
that case.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=88758


Cc: stable@vger.kernel.org
Reviewed-by: default avatarChristian König <christian.koenig@amd.com>
Signed-off-by: default avatarMichel Dänzer <michel.daenzer@amd.com>
Signed-off-by: default avatarAlex Deucher <alexander.deucher@amd.com>
parent 082452e1

drivers/gpu/drm/radeon/radeon_object.c

+12 −0
Original line number Diff line number Diff line
@@ -238,6 +238,18 @@ int radeon_bo_create(struct radeon_device *rdev, 
	 * See https://bugs.freedesktop.org/show_bug.cgi?id=84627

	 */

	bo->flags &= ~RADEON_GEM_GTT_WC;

#elif defined(CONFIG_X86) && !defined(CONFIG_X86_PAT)

	/* Don't try to enable write-combining when it can't work, or things

	 * may be slow

	 * See https://bugs.freedesktop.org/show_bug.cgi?id=88758

	 */



#warning Please enable CONFIG_MTRR and CONFIG_X86_PAT for better performance \

	 thanks to write-combining



	DRM_INFO_ONCE("Please enable CONFIG_MTRR and CONFIG_X86_PAT for "

		      "better performance thanks to write-combining\n");

	bo->flags &= ~RADEON_GEM_GTT_WC;

#endif



	radeon_ttm_placement_from_domain(bo, domain);