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authorMichel Dänzer <michel.daenzer@amd.com>2015-02-04 04:19:51 +0300
committerAlex Deucher <alexander.deucher@amd.com>2015-02-11 20:01:33 +0300
commita53fa43873b88bad15a2eb1f01dc5efa689625ce (patch)
tree2513dcac20515684498f4530f8c834866125e480 /drivers/gpu/drm/radeon/radeon_object.c
parent082452e125fe27a9f43add2269dfa2341fb71d30 (diff)
downloadlinux-a53fa43873b88bad15a2eb1f01dc5efa689625ce.tar.xz
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: Christian König <christian.koenig@amd.com> Signed-off-by: Michel Dänzer <michel.daenzer@amd.com> Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Diffstat (limited to 'drivers/gpu/drm/radeon/radeon_object.c')
-rw-r--r--drivers/gpu/drm/radeon/radeon_object.c12
1 files changed, 12 insertions, 0 deletions
diff --git a/drivers/gpu/drm/radeon/radeon_object.c b/drivers/gpu/drm/radeon/radeon_object.c
index 1d955776f4d0..43e09942823e 100644
--- a/drivers/gpu/drm/radeon/radeon_object.c
+++ b/drivers/gpu/drm/radeon/radeon_object.c
@@ -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);