From: John Harrison <john.c.harri...@intel.com>

The GPU scheduler can cause seqno values to become out of order. This means that
a straight forward 'is seqno X > seqno Y' test is no longer valid. Instead, a
call into the scheduler must be made to see if the value being queried is known
to be out of order.
---
 drivers/gpu/drm/i915/i915_drv.h       |   23 ++++++++++++++++++++++-
 drivers/gpu/drm/i915/i915_gem.c       |   14 +++++++-------
 drivers/gpu/drm/i915/i915_irq.c       |    4 ++--
 drivers/gpu/drm/i915/i915_scheduler.c |   20 ++++++++++++++++++++
 drivers/gpu/drm/i915/i915_scheduler.h |    3 +++
 5 files changed, 54 insertions(+), 10 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 6e592d3..0977653 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -2214,14 +2214,35 @@ int i915_gem_dumb_create(struct drm_file *file_priv,
                         struct drm_mode_create_dumb *args);
 int i915_gem_mmap_gtt(struct drm_file *file_priv, struct drm_device *dev,
                      uint32_t handle, uint64_t *offset);
+
+bool i915_scheduler_is_seqno_in_flight(struct intel_engine_cs *ring,
+                               uint32_t seqno, bool *completed);
+
 /**
  * Returns true if seq1 is later than seq2.
  */
 static inline bool
-i915_seqno_passed(uint32_t seq1, uint32_t seq2)
+i915_seqno_passed(struct intel_engine_cs *ring, uint32_t seq1, uint32_t seq2)
 {
+#ifdef CONFIG_DRM_I915_SCHEDULER
+       bool    completed;
+
+       if (i915_scheduler_is_seqno_in_flight(ring, seq2, &completed))
+               return completed;
+#endif
+
        return (int32_t)(seq1 - seq2) >= 0;
 }
+static inline int32_t
+i915_compare_seqno_values(uint32_t seq1, uint32_t seq2)
+{
+       int32_t diff = seq1 - seq2;
+
+       if (!diff)
+               return 0;
+
+       return (diff > 0) ? 1 : -1;
+}
 
 int __must_check i915_gem_get_seqno(struct drm_device *dev, u32 *seqno);
 int __must_check i915_gem_set_seqno(struct drm_device *dev, u32 seqno);
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 7e53446..fece5e7 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -1165,7 +1165,7 @@ static int __wait_seqno(struct intel_engine_cs *ring, u32 
seqno,
 
        WARN(dev_priv->pm.irqs_disabled, "IRQs disabled\n");
 
-       if (i915_seqno_passed(ring->get_seqno(ring, true), seqno))
+       if (i915_seqno_passed(ring, ring->get_seqno(ring, true), seqno))
                return 0;
 
        timeout_expire = timeout ? jiffies + 
timespec_to_jiffies_timeout(timeout) : 0;
@@ -1201,7 +1201,7 @@ static int __wait_seqno(struct intel_engine_cs *ring, u32 
seqno,
                        break;
                }
 
-               if (i915_seqno_passed(ring->get_seqno(ring, false), seqno)) {
+               if (i915_seqno_passed(ring, ring->get_seqno(ring, false), 
seqno)) {
                        ret = 0;
                        break;
                }
@@ -2243,7 +2243,7 @@ i915_gem_object_retire(struct drm_i915_gem_object *obj)
        if (ring == NULL)
                return;
 
-       if (i915_seqno_passed(ring->get_seqno(ring, true),
+       if (i915_seqno_passed(ring, ring->get_seqno(ring, true),
                              obj->last_read_seqno))
                i915_gem_object_move_to_inactive(obj);
 }
@@ -2489,7 +2489,7 @@ i915_gem_find_active_request(struct intel_engine_cs *ring)
        completed_seqno = ring->get_seqno(ring, false);
 
        list_for_each_entry(request, &ring->request_list, list) {
-               if (i915_seqno_passed(completed_seqno, request->seqno))
+               if (i915_seqno_passed(ring, completed_seqno, request->seqno))
                        continue;
 
                return request;
@@ -2620,7 +2620,7 @@ i915_gem_retire_requests_ring(struct intel_engine_cs 
*ring)
         */
 
        list_for_each_entry_safe(req, req_next, &ring->request_list, list) {
-               if (!i915_seqno_passed(seqno, req->seqno))
+               if (!i915_seqno_passed(ring, seqno, req->seqno))
                        continue;
 
                trace_i915_gem_request_retire(ring, req->seqno);
@@ -2639,14 +2639,14 @@ i915_gem_retire_requests_ring(struct intel_engine_cs 
*ring)
         * before we free the context associated with the requests.
         */
        list_for_each_entry_safe(obj, obj_next, &ring->active_list, ring_list) {
-               if (!i915_seqno_passed(seqno, obj->last_read_seqno))
+               if (!i915_seqno_passed(ring, seqno, obj->last_read_seqno))
                        continue;
 
                i915_gem_object_move_to_inactive(obj);
        }
 
        if (unlikely(ring->trace_irq_seqno &&
-                    i915_seqno_passed(seqno, ring->trace_irq_seqno))) {
+                    i915_seqno_passed(ring, seqno, ring->trace_irq_seqno))) {
                ring->irq_put(ring);
                ring->trace_irq_seqno = 0;
        }
diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c
index 00358f9..eff08a3e 100644
--- a/drivers/gpu/drm/i915/i915_irq.c
+++ b/drivers/gpu/drm/i915/i915_irq.c
@@ -2750,7 +2750,7 @@ static bool
 ring_idle(struct intel_engine_cs *ring, u32 seqno)
 {
        return (list_empty(&ring->request_list) ||
-               i915_seqno_passed(seqno, ring_last_seqno(ring)));
+               i915_seqno_passed(ring, seqno, ring_last_seqno(ring)));
 }
 
 static bool
@@ -2862,7 +2862,7 @@ static int semaphore_passed(struct intel_engine_cs *ring)
        if (ctl & RING_WAIT_SEMAPHORE && semaphore_passed(signaller) < 0)
                return -1;
 
-       return i915_seqno_passed(signaller->get_seqno(signaller, false), seqno);
+       return i915_seqno_passed(ring, signaller->get_seqno(signaller, false), 
seqno);
 }
 
 static void semaphore_clear_deadlocks(struct drm_i915_private *dev_priv)
diff --git a/drivers/gpu/drm/i915/i915_scheduler.c 
b/drivers/gpu/drm/i915/i915_scheduler.c
index 9ec0225..e9aa566 100644
--- a/drivers/gpu/drm/i915/i915_scheduler.c
+++ b/drivers/gpu/drm/i915/i915_scheduler.c
@@ -49,6 +49,26 @@ int i915_scheduler_init(struct drm_device *dev)
        return 0;
 }
 
+bool i915_scheduler_is_seqno_in_flight(struct intel_engine_cs *ring,
+                              uint32_t seqno, bool *completed)
+{
+       struct drm_i915_private *dev_priv = ring->dev->dev_private;
+       struct i915_scheduler   *scheduler = dev_priv->scheduler;
+       bool                    found = false;
+       unsigned long           flags;
+
+       if (!scheduler)
+               return false;
+
+       spin_lock_irqsave(&scheduler->lock, flags);
+
+       /* Do stuff... */
+
+       spin_unlock_irqrestore(&scheduler->lock, flags);
+
+       return found;
+}
+
 #else   /* CONFIG_DRM_I915_SCHEDULER */
 
 int i915_scheduler_init(struct drm_device *dev)
diff --git a/drivers/gpu/drm/i915/i915_scheduler.h 
b/drivers/gpu/drm/i915/i915_scheduler.h
index bbe1934..67260b7 100644
--- a/drivers/gpu/drm/i915/i915_scheduler.h
+++ b/drivers/gpu/drm/i915/i915_scheduler.h
@@ -35,6 +35,9 @@ struct i915_scheduler {
        uint32_t    index;
 };
 
+bool        i915_scheduler_is_seqno_in_flight(struct intel_engine_cs *ring,
+                                             uint32_t seqno, bool *completed);
+
 #endif  /* CONFIG_DRM_I915_SCHEDULER */
 
 #endif  /* _I915_SCHEDULER_H_ */
-- 
1.7.9.5

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