drm/i915/execlists: Use coherent writes into the context image
That we use a WB mapping for updating the RING_TAIL register inside the
context image even on !llc machines has been a source of consternation
for every reader. It appears to work on bsw+, but it may just have been
that we have been incredibly bad at detecting the errors.
v2: With extra enthusiasm.
v3: Drop force of map type for pinned default_state as by the time we
pin it, the map type is always WB and doesn't conflict with the earlier
use by ce->state.
v4: Transfer engine->default_state from MAP_WC to MAP_WB on creation so
we do not need the MAP_FORCE littered around the backends
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180914123504.2062-3-chris@chris-wilson.co.uk
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index ea6c6f7..0509fd0 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -3096,6 +3096,12 @@ enum i915_map_type {
I915_MAP_FORCE_WC = I915_MAP_WC | I915_MAP_OVERRIDE,
};
+static inline enum i915_map_type
+i915_coherent_map_type(struct drm_i915_private *i915)
+{
+ return HAS_LLC(i915) ? I915_MAP_WB : I915_MAP_WC;
+}
+
/**
* i915_gem_object_pin_map - return a contiguous mapping of the entire object
* @obj: the object to map into kernel address space