[Intel-gfx] [PATCH 09/18] 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 | 49 +++++++++++++++++++++++++++++++++
 1 file changed, 49 insertions(+)

diff --git a/drivers/gpu/drm/i915/i915_gem_request.c b/drivers/gpu/drm/i915/i915_gem_request.c
index 5817ec55849f..1b8463a474bb 100644
--- a/drivers/gpu/drm/i915/i915_gem_request.c
+++ b/drivers/gpu/drm/i915/i915_gem_request.c
@@ -770,6 +770,49 @@ bool __i915_spin_request(const struct drm_i915_gem_request *req,
 	return false;
 }
 
+static long
+__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;
+	wait_queue_head_t *q = &request->i915->gpu_error.wait_queue;
+	DEFINE_WAIT(reset);
+	DEFINE_WAIT(wait);
+
+	if (flags & I915_WAIT_LOCKED)
+		add_wait_queue(q, &reset);
+
+	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);
+			reset_wait_queue(q, &reset);
+			continue;
+		}
+
+		if (signal_pending_state(state, current)) {
+			timeout = -ERESTARTSYS;
+			break;
+		}
+
+		timeout = io_schedule_timeout(timeout);
+	} while (timeout);
+	finish_wait(&request->submit.wait, &wait);
+
+	if (flags & I915_WAIT_LOCKED)
+		remove_wait_queue(q, &reset);
+
+	return timeout;
+}
+
 /**
  * i915_wait_request - wait until execution of request has finished
  * @req: duh!
@@ -808,6 +851,12 @@ long i915_wait_request(struct drm_i915_gem_request *req,
 
 	trace_i915_gem_request_wait_begin(req);
 
+	if (!i915_sw_fence_done(&req->submit)) {
+		timeout = __i915_request_wait_for_submit(req, flags, timeout);
+		if (timeout < 0)
+			goto complete;
+	}
+
 	/* Optimistic short spin before touching IRQs */
 	if (i915_spin_request(req, state, 5))
 		goto complete;
-- 
2.9.3