[PATCH 23/26] drm/i915: Wait first for submission, before waiting for request completion

[Chris Wilson]

In future patches, we will no longer be able to wait on a static global
seqno and instead have to break our wait up into phases. First we wait
for the global seqno assignment (upon submission to hardware), and once
submitted we wait for the hardware to complete.

Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
---
 drivers/gpu/drm/i915/i915_gem_request.c | 39 +++++++++++++++++++++++++++++++++
 1 file changed, 39 insertions(+)

diff --git a/drivers/gpu/drm/i915/i915_gem_request.c b/drivers/gpu/drm/i915/i915_gem_request.c
index 5a18e08075fb..33aba45cdce5 100644
--- a/drivers/gpu/drm/i915/i915_gem_request.c
+++ b/drivers/gpu/drm/i915/i915_gem_request.c
@@ -727,6 +727,39 @@ bool __i915_spin_request(const struct drm_i915_gem_request *req,
 	return false;
 }
 
+static int __i915_request_wait_for_submit(struct drm_i915_gem_request *request,
+					  unsigned int flags,
+					  long timeout)
+{
+	const int state = flags & I915_WAIT_INTERRUPTIBLE ?
+		TASK_INTERRUPTIBLE : TASK_UNINTERRUPTIBLE;
+	DEFINE_WAIT(wait);
+
+	do {
+		prepare_to_wait(&request->submit.wait, &wait, state);
+
+		if (i915_sw_fence_done(&request->submit))
+			break;
+
+		if (flags & I915_WAIT_LOCKED &&
+		    i915_reset_in_progress(&request->i915->gpu_error)) {
+			__set_current_state(TASK_RUNNING);
+			i915_reset(request->i915);
+			continue;
+		}
+
+		if (signal_pending_state(state, current)) {
+			timeout = -ERESTARTSYS;
+			break;
+		}
+
+		timeout = io_schedule_timeout(timeout);
+	} while (timeout > 0);
+	finish_wait(&request->submit.wait, &wait);
+
+	return timeout;
+}
+
 /**
  * i915_wait_request - wait until execution of request has finished
  * @req: duh!
@@ -768,6 +801,12 @@ long i915_wait_request(struct drm_i915_gem_request *req,
 	if (flags & I915_WAIT_LOCKED)
 		add_wait_queue(&req->i915->gpu_error.wait_queue, &reset);
 
+	if (!i915_sw_fence_done(&req->submit)) {
+		timeout = __i915_request_wait_for_submit(req, flags, timeout);
+		if (timeout < 0)
+			goto complete;
+	}
+
 	/* Optimistic spin for the next ~jiffie before touching IRQs */
 	if (i915_spin_request(req, state, 5))
 		goto complete;
-- 
2.9.3