drm/i915: Make closing request flush mandatory

For symmetry, simplicity and ensuring the request is always truly idle
upon its completion, always emit the closing flush prior to emitting the
request breadcrumb. Previously, we would only emit the flush if we had
started a user batch, but this just leaves all the other paths open to
speculation (do they affect the GPU caches or not?) With mm switching, a
key requirement is that the GPU is flushed and invalidated before hand,
so for absolute safety, we want that closing flush be mandatory.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180612105135.4459-1-chris@chris-wilson.co.uk

1 files changed, 1 insertions, 3 deletions

diff --git a/drivers/gpu/drm/i915/i915_request.h b/drivers/gpu/drm/i915/i915_request.h
index 0e9aba53d0e4..7ee220ded9c9 100644
--- a/drivers/gpu/drm/i915/i915_request.h
+++ b/drivers/gpu/drm/i915/i915_request.h
@@ -253,9 +253,7 @@ int i915_request_await_object(struct i915_request *to,
 int i915_request_await_dma_fence(struct i915_request *rq,
 				 struct dma_fence *fence);
 
-void __i915_request_add(struct i915_request *rq, bool flush_caches);
-#define i915_request_add(rq) \
-	__i915_request_add(rq, false)
+void i915_request_add(struct i915_request *rq);
 
 void __i915_request_submit(struct i915_request *request);
 void i915_request_submit(struct i915_request *request);