On Wed, Feb 4, 2015 at 4:49 AM, Christian König <deathsimple@xxxxxxxxxxx> wrote: > Am 04.02.2015 um 02:19 schrieb Michel Dänzer: >> >> From: Michel Dänzer <michel.daenzer@xxxxxxx> >> >> 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@xxxxxxxxxxxxxxx >> Signed-off-by: Michel Dänzer <michel.daenzer@xxxxxxx> > > > 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@xxxxxxx> Applied to my 3.20 tree. Thanks! Alex > > 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-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); > > > _______________________________________________ > dri-devel mailing list > dri-devel@xxxxxxxxxxxxxxxxxxxxx > http://lists.freedesktop.org/mailman/listinfo/dri-devel _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/dri-devel
