Am 04.02.2015 um 02:19 schrieb Michel Dänzer:
From: Michel Dänzer michel.daenzer@amd.com
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 Signed-off-by: Michel Dänzer michel.daenzer@amd.com
Interesting I wonder what the rational behind this is. I mean CONFIG_X86_PAT will obviously affect write combining, but why does it slow down things if we request something that the kernel isn't configured for?
Anyway, patch is Reviewed-by: Christian König christian.koenig@amd.com
Regards, Christian.
drivers/gpu/drm/radeon/radeon_object.c | 12 ++++++++++++ 1 file changed, 12 insertions(+)
diff --git a/drivers/gpu/drm/radeon/radeon_object.c b/drivers/gpu/drm/radeon/radeon_object.c index 7d68223..bd3df10 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-combiningDRM_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);