[PATCH 50/74] wait-for-space

[Chris Wilson]

---
 drivers/gpu/drm/i915/intel_lrc.c        |  7 ++---
 drivers/gpu/drm/i915/intel_ringbuffer.c | 56 +++++++++++++++++++++------------
 drivers/gpu/drm/i915/intel_ringbuffer.h |  1 +
 3 files changed, 39 insertions(+), 25 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_lrc.c b/drivers/gpu/drm/i915/intel_lrc.c
index b5f6ab35aa28..95188b4ce33f 100644
--- a/drivers/gpu/drm/i915/intel_lrc.c
+++ b/drivers/gpu/drm/i915/intel_lrc.c
@@ -993,7 +993,6 @@ static int execlists_request_alloc(struct drm_i915_gem_request *request)
 {
 	struct intel_engine_cs *engine = request->engine;
 	struct intel_context *ce = &request->ctx->engine[engine->id];
-	u32 *cs;
 	int ret;
 
 	GEM_BUG_ON(!ce->pin_count);
@@ -1015,11 +1014,9 @@ static int execlists_request_alloc(struct drm_i915_gem_request *request)
 			goto err;
 	}
 
-	cs = intel_ring_begin(request, 0);
-	if (IS_ERR(cs)) {
-		ret = PTR_ERR(cs);
+	ret = intel_ring_wait_for_space(request->ring, request->reserved_space);
+	if (ret)
 		goto err_unreserve;
-	}
 
 	if (!ce->initialised) {
 		ret = engine->init_context(request);
diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.c b/drivers/gpu/drm/i915/intel_ringbuffer.c
index 7e13bfa7e1cd..b4dc8382e925 100644
--- a/drivers/gpu/drm/i915/intel_ringbuffer.c
+++ b/drivers/gpu/drm/i915/intel_ringbuffer.c
@@ -1522,7 +1522,7 @@ void intel_legacy_submission_resume(struct drm_i915_private *dev_priv)
 
 static int ring_request_alloc(struct drm_i915_gem_request *request)
 {
-	u32 *cs;
+	int ret;
 
 	GEM_BUG_ON(!request->ctx->engine[request->engine->id].pin_count);
 
@@ -1532,37 +1532,24 @@ static int ring_request_alloc(struct drm_i915_gem_request *request)
 	 */
 	request->reserved_space += LEGACY_REQUEST_SIZE;
 
-	cs = intel_ring_begin(request, 0);
-	if (IS_ERR(cs))
-		return PTR_ERR(cs);
+	ret = intel_ring_wait_for_space(request->ring, request->reserved_space);
+	if (ret)
+		return ret;
 
 	request->reserved_space -= LEGACY_REQUEST_SIZE;
 	return 0;
 }
 
-static noinline int wait_for_space(struct drm_i915_gem_request *req,
-				   unsigned int bytes)
+static noinline int wait_for_space(struct intel_ring *ring, unsigned int bytes)
 {
-	struct intel_ring *ring = req->ring;
 	struct drm_i915_gem_request *target;
 	long timeout;
 
-	lockdep_assert_held(&req->i915->drm.struct_mutex);
+	lockdep_assert_held(&ring->vma->vm->i915->drm.struct_mutex);
 
 	if (intel_ring_update_space(ring) >= bytes)
 		return 0;
 
-	/*
-	 * Space is reserved in the ringbuffer for finalising the request,
-	 * as that cannot be allowed to fail. During request finalisation,
-	 * reserved_space is set to 0 to stop the overallocation and the
-	 * assumption is that then we never need to wait (which has the
-	 * risk of failing with EINTR).
-	 *
-	 * See also i915_gem_request_alloc() and i915_add_request().
-	 */
-	GEM_BUG_ON(!req->reserved_space);
-
 	list_for_each_entry(target, &ring->request_list, ring_link) {
 		/* Would completion of this request free enough space? */
 		if (bytes <= __intel_ring_space(target->postfix,
@@ -1586,6 +1573,22 @@ static noinline int wait_for_space(struct drm_i915_gem_request *req,
 	return 0;
 }
 
+int intel_ring_wait_for_space(struct intel_ring *ring, unsigned int bytes)
+{
+	GEM_BUG_ON(bytes > ring->effective_size);
+	if (unlikely(bytes > ring->effective_size - ring->emit))
+		bytes += ring->size - ring->emit;
+
+	if (unlikely(bytes > ring->space)) {
+		int ret = wait_for_space(ring, bytes);
+		if (unlikely(ret))
+			return ret;
+	}
+
+	GEM_BUG_ON(ring->space < bytes);
+	return 0;
+}
+
 u32 *intel_ring_begin(struct drm_i915_gem_request *req,
 		      unsigned int num_dwords)
 {
@@ -1625,7 +1628,20 @@ u32 *intel_ring_begin(struct drm_i915_gem_request *req,
 	}
 
 	if (unlikely(total_bytes > ring->space)) {
-		int ret = wait_for_space(req, total_bytes);
+		int ret;
+
+		/*
+		 * Space is reserved in the ringbuffer for finalising the
+		 * request, as that cannot be allowed to fail. During request
+		 * finalisation, reserved_space is set to 0 to stop the
+		 * overallocation and the assumption is that then we never need
+		 * to wait (which has the risk of failing with EINTR).
+		 *
+		 * See also i915_gem_request_alloc() and i915_add_request().
+		 */
+		GEM_BUG_ON(!req->reserved_space);
+
+		ret = wait_for_space(ring, total_bytes);
 		if (unlikely(ret))
 			return ERR_PTR(ret);
 	}
diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.h b/drivers/gpu/drm/i915/intel_ringbuffer.h
index 1e196ac9e0f3..0e306f2e3ed6 100644
--- a/drivers/gpu/drm/i915/intel_ringbuffer.h
+++ b/drivers/gpu/drm/i915/intel_ringbuffer.h
@@ -519,6 +519,7 @@ void intel_legacy_submission_resume(struct drm_i915_private *dev_priv);
 
 int __must_check intel_ring_cacheline_align(struct drm_i915_gem_request *req);
 
+int intel_ring_wait_for_space(struct intel_ring *ring, unsigned int bytes);
 u32 __must_check *intel_ring_begin(struct drm_i915_gem_request *req,
 				   unsigned int n);
 
-- 
2.14.1