[Intel-gfx] [PATCH 27/29] drm/i915: Interrupt driven request completion

[John.C.Harrison at Intel.com]

From: John Harrison <John.C.Harrison at Intel.com>

Added a hook to the ring noftification code to process request completion. This
means that there is no longer a need to explicitly process request completions
every time a request object is tested. Instead, the test code simply becomes
'return req->completed'. Obviously, this only works if ring interrupts are
enabled, however, this is already the case for the duration of __wait_request()
which is the point where the driver really needs to know.

To prevent stale requests floating around indefinitely, the retire work handler
also now performs a completion check periodically.

For: VIZ-4377
Signed-off-by: John Harrison <John.C.Harrison at Intel.com>
---
 drivers/gpu/drm/i915/i915_drv.h |    5 -----
 drivers/gpu/drm/i915/i915_gem.c |   10 ++++++++++
 drivers/gpu/drm/i915/i915_irq.c |    2 ++
 3 files changed, 12 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 1a3db6f..ab89fd5 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -2007,11 +2007,6 @@ static inline void i915_gem_request_assign(struct drm_i915_gem_request **pdst,
 static inline bool i915_gem_request_completed(struct drm_i915_gem_request *req,
 					      bool lazy_coherency)
 {
-	if (req->complete)
-		return true;
-
-	i915_gem_complete_requests_ring(req->ring, lazy_coherency);
-
 	return req->complete;
 }
 
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index c4facbd..98052e6 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -1183,6 +1183,11 @@ static int __wait_request(struct drm_i915_gem_request *req,
 	if (!irq_test_in_progress && WARN_ON(!ring->irq_get(ring)))
 		return -ENODEV;
 
+	/* Completion status should be interrupt driven but it is possible
+	 * the request popped out before the interrupt was enabled. So do an
+	 * explicit check now... */
+	i915_gem_complete_requests_ring(req->ring, false);
+
 	/* Record current time in case interrupted by signal, or wedged */
 	trace_i915_gem_request_wait_begin(req);
 	before = ktime_get_raw_ns();
@@ -2405,6 +2410,10 @@ int __i915_add_request(struct intel_engine_cs *ring,
 	list_add_tail(&request->list, &ring->request_list);
 	request->file_priv = NULL;
 
+	/* Avoid race condition where the request completes before it has
+	 * been added to the list. */
+	ring->last_read_seqno = 0;
+
 	if (file) {
 		struct drm_i915_file_private *file_priv = file->driver_priv;
 
@@ -2768,6 +2777,7 @@ i915_gem_retire_requests(struct drm_device *dev)
 	int i;
 
 	for_each_ring(ring, dev_priv, i) {
+		i915_gem_complete_requests_ring(ring, false);
 		i915_gem_retire_requests_ring(ring);
 		idle &= list_empty(&ring->request_list);
 	}
diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c
index 21e1d69..1f8f708 100644
--- a/drivers/gpu/drm/i915/i915_irq.c
+++ b/drivers/gpu/drm/i915/i915_irq.c
@@ -979,6 +979,8 @@ static void notify_ring(struct drm_device *dev,
 
 	trace_i915_gem_request_complete(ring);
 
+	i915_gem_complete_requests_ring(ring, false);
+
 	if (drm_core_check_feature(dev, DRIVER_MODESET))
 		intel_notify_mmio_flip(ring);
 
-- 
1.7.9.5