drm/i915: Unconditionally flush any chipset buffers before execbuf
If userspace is asynchronously streaming into the batch or other
execobjects, we may not flush those writes along with a change in cache
domain (as there is no change). Therefore those writes may end up in
internal chipset buffers and not visible to the GPU upon execution. We
must issue a flush command or otherwise we encounter incoherency in the
batchbuffers and the GPU executing invalid commands (i.e. hanging) quite
regularly.
v2: Throw a paranoid wmb() into the general flush so that we remain
consistent with before.
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=90841
Fixes: 1816f9236303 ("drm/i915: Support creation of unbound wc user...")
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Akash Goel <akash.goel@intel.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>
Tested-by: Matti Hämäläinen <ccr@tnsp.org>
Cc: stable@vger.kernel.org
Reviewed-by: Mika Kuoppala <mika.kuoppala@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20160818161718.27187-1-chris@chris-wilson.co.uk
(cherry picked from commit 600f436801deae65e48404847b61c89b4944e355)
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
diff --git a/drivers/gpu/drm/i915/i915_gem_execbuffer.c b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
index 1978633..b35e5b6 100644
--- a/drivers/gpu/drm/i915/i915_gem_execbuffer.c
+++ b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
@@ -943,8 +943,6 @@
{
const unsigned other_rings = ~intel_engine_flag(req->engine);
struct i915_vma *vma;
- uint32_t flush_domains = 0;
- bool flush_chipset = false;
int ret;
list_for_each_entry(vma, vmas, exec_list) {
@@ -957,16 +955,11 @@
}
if (obj->base.write_domain & I915_GEM_DOMAIN_CPU)
- flush_chipset |= i915_gem_clflush_object(obj, false);
-
- flush_domains |= obj->base.write_domain;
+ i915_gem_clflush_object(obj, false);
}
- if (flush_chipset)
- i915_gem_chipset_flush(req->engine->i915);
-
- if (flush_domains & I915_GEM_DOMAIN_GTT)
- wmb();
+ /* Unconditionally flush any chipset caches (for streaming writes). */
+ i915_gem_chipset_flush(req->engine->i915);
/* Unconditionally invalidate gpu caches and ensure that we do flush
* any residual writes from the previous batch.