drm/i915: Add flag to i915_add_request() to skip the cache flush

In order to explcitly track all GPU work (and completely remove the outstanding
lazy request), it is necessary to add extra i915_add_request() calls to various
places. Some of these do not need the implicit cache flush done as part of the
standard batch buffer submission process.

This patch adds a flag to _add_request() to specify whether the flush is
required or not.

For: VIZ-5115
Signed-off-by: John Harrison <John.C.Harrison@Intel.com>
Reviewed-by: Tomas Elf <tomas.elf@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/i915_drv.h

@@ -2890,9 +2890,12 @@ int __must_check i915_gpu_idle(struct drm_device *dev);
 int __must_check i915_gem_suspend(struct drm_device *dev);
 void __i915_add_request(struct intel_engine_cs *ring,
 			struct drm_file *file,
-			struct drm_i915_gem_object *batch_obj);
+			struct drm_i915_gem_object *batch_obj,
+			bool flush_caches);
 #define i915_add_request(ring) \
-	__i915_add_request(ring, NULL, NULL)
+	__i915_add_request(ring, NULL, NULL, true)
+#define i915_add_request_no_flush(ring) \
+	__i915_add_request(ring, NULL, NULL, false)
 int __i915_wait_request(struct drm_i915_gem_request *req,
 			unsigned reset_counter,
 			bool interruptible,

drivers/gpu/drm/i915/i915_gem.c

@@ -2470,7 +2470,8 @@ i915_gem_get_seqno(struct drm_device *dev, u32 *seqno)
  */
 void __i915_add_request(struct intel_engine_cs *ring,
 			struct drm_file *file,
-			struct drm_i915_gem_object *obj)
+			struct drm_i915_gem_object *obj,
+			bool flush_caches)
 {
 	struct drm_i915_private *dev_priv = ring->dev->dev_private;
 	struct drm_i915_gem_request *request;
@@ -2502,12 +2503,14 @@ void __i915_add_request(struct intel_engine_cs *ring,
 	 * is that the flush _must_ happen before the next request, no matter
 	 * what.
 	 */
-	if (i915.enable_execlists)
-		ret = logical_ring_flush_all_caches(ringbuf, request->ctx);
-	else
-		ret = intel_ring_flush_all_caches(ring);
-	/* Not allowed to fail! */
-	WARN(ret, "*_ring_flush_all_caches failed: %d!\n", ret);
+	if (flush_caches) {
+		if (i915.enable_execlists)
+			ret = logical_ring_flush_all_caches(ringbuf, request->ctx);
+		else
+			ret = intel_ring_flush_all_caches(ring);
+		/* Not allowed to fail! */
+		WARN(ret, "*_ring_flush_all_caches failed: %d!\n", ret);
+	}
 
 	/* Record the position of the start of the request so that
 	 * should we detect the updated seqno part-way through the

drivers/gpu/drm/i915/i915_gem_execbuffer.c

@@ -1066,7 +1066,7 @@ i915_gem_execbuffer_retire_commands(struct i915_execbuffer_params *params)
 	params->ring->gpu_caches_dirty = true;
 
 	/* Add a breadcrumb for the completion of the batch buffer */
-	__i915_add_request(params->ring, params->file, params->batch_obj);
+	__i915_add_request(params->ring, params->file, params->batch_obj, true);
 }
 
 static int

drivers/gpu/drm/i915/i915_gem_render_state.c

@@ -173,7 +173,7 @@ int i915_gem_render_state_init(struct intel_engine_cs *ring)
 
 	i915_vma_move_to_active(i915_gem_obj_to_ggtt(so.obj), ring);
 
-	__i915_add_request(ring, NULL, so.obj);
+	__i915_add_request(ring, NULL, so.obj, true);
 	/* __i915_add_request moves object to inactive if it fails */
 out:
 	i915_gem_render_state_fini(&so);

drivers/gpu/drm/i915/intel_lrc.c

@@ -1599,7 +1599,7 @@ static int intel_lr_context_render_state_init(struct intel_engine_cs *ring,
 
 	i915_vma_move_to_active(i915_gem_obj_to_ggtt(so.obj), ring);
 
-	__i915_add_request(ring, file, so.obj);
+	__i915_add_request(ring, file, so.obj, true);
 	/* intel_logical_ring_add_request moves object to inactive if it
 	 * fails */
 out: