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| author | Chris Wilson <chris@chris-wilson.co.uk> | 2017-04-12 12:01:11 +0100 |
|---|---|---|
| committer | Chris Wilson <chris@chris-wilson.co.uk> | 2017-04-12 12:35:17 +0100 |
| commit | e22d8e3c69a9f432b40baaaf3f894a128fdc2222 (patch) | |
| tree | f076dadac5c963736a8fe1a25d31013f512d0366 /drivers/gpu/drm/i915/selftests/i915_gem_coherency.c | |
| parent | ef74921bc679232c6590afa881d3ea605ebdddd8 (diff) | |
| download | linux-e22d8e3c69a9f432b40baaaf3f894a128fdc2222.tar.bz2 | |
drm/i915: Treat WC a separate cache domain
When discussing a new WC mmap, we based the interface upon the
assumption that GTT was fully coherent. How naive! Commits 3b5724d702ef
("drm/i915: Wait for writes through the GTT to land before reading
back") and ed4596ea992d ("drm/i915/guc: WA to address the Ringbuffer
coherency issue") demonstrate that writes through the GTT are indeed
delayed and may be overtaken by direct WC access. To be safe, if
userspace is mixing WC mmaps with other potential GTT access (pwrite,
GTT mmaps) it should use set_domain(WC).
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=96563
Testcase: igt/gem_pwrite/small-gtt*
Testcase: igt/drv_selftest/coherency
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170412110111.26626-2-chris@chris-wilson.co.uk
Diffstat (limited to 'drivers/gpu/drm/i915/selftests/i915_gem_coherency.c')
| -rw-r--r-- | drivers/gpu/drm/i915/selftests/i915_gem_coherency.c | 10 |
1 files changed, 2 insertions, 8 deletions
diff --git a/drivers/gpu/drm/i915/selftests/i915_gem_coherency.c b/drivers/gpu/drm/i915/selftests/i915_gem_coherency.c index c61d0ef2118c..95d4aebc0181 100644 --- a/drivers/gpu/drm/i915/selftests/i915_gem_coherency.c +++ b/drivers/gpu/drm/i915/selftests/i915_gem_coherency.c @@ -138,10 +138,7 @@ static int wc_set(struct drm_i915_gem_object *obj, typeof(v) *map; int err; - /* XXX GTT write followed by WC write go missing */ - flush_write_domain(obj, ~0); - - err = i915_gem_object_set_to_gtt_domain(obj, true); + err = i915_gem_object_set_to_wc_domain(obj, true); if (err) return err; @@ -162,10 +159,7 @@ static int wc_get(struct drm_i915_gem_object *obj, typeof(v) map; int err; - /* XXX WC write followed by GTT write go missing */ - flush_write_domain(obj, ~0); - - err = i915_gem_object_set_to_gtt_domain(obj, false); + err = i915_gem_object_set_to_wc_domain(obj, false); if (err) return err; |