We would like to start doing some bookkeeping at the beginning, between
contexts and at the end of execlists submission. We already mark the
beginning and end using EXECLISTS_ACTIVE_USER, to provide an indication
when the HW is idle. This give us a pair of sequence points we can then
expand on for further bookkeeping.

Signed-off-by: Chris Wilson <ch...@chris-wilson.co.uk>
Cc: Mika Kuoppala <mika.kuopp...@linux.intel.com>
Cc: Francisco Jerez <curroje...@riseup.net>
---
 drivers/gpu/drm/i915/intel_lrc.c        | 42 ++++++++++++++++++++++++---------
 drivers/gpu/drm/i915/intel_ringbuffer.h | 11 ++++++++-
 2 files changed, 41 insertions(+), 12 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_lrc.c b/drivers/gpu/drm/i915/intel_lrc.c
index f60b61bf8b3b..2d2d33becce3 100644
--- a/drivers/gpu/drm/i915/intel_lrc.c
+++ b/drivers/gpu/drm/i915/intel_lrc.c
@@ -374,6 +374,19 @@ execlists_context_status_change(struct i915_request *rq, 
unsigned long status)
                                   status, rq);
 }
 
+static inline void
+execlists_user_begin(struct intel_engine_execlists *execlists,
+                    const struct execlist_port *port)
+{
+       execlists_set_active_once(execlists, EXECLISTS_ACTIVE_USER);
+}
+
+static inline void
+execlists_user_end(struct intel_engine_execlists *execlists)
+{
+       execlists_clear_active(execlists, EXECLISTS_ACTIVE_USER);
+}
+
 static inline void
 execlists_context_schedule_in(struct i915_request *rq)
 {
@@ -711,7 +724,7 @@ static void execlists_dequeue(struct intel_engine_cs 
*engine)
        spin_unlock_irq(&engine->timeline->lock);
 
        if (submit) {
-               execlists_set_active(execlists, EXECLISTS_ACTIVE_USER);
+               execlists_user_begin(execlists, execlists->port);
                execlists_submit_ports(engine);
        }
 
@@ -742,7 +755,7 @@ execlists_cancel_port_requests(struct 
intel_engine_execlists * const execlists)
                port++;
        }
 
-       execlists_clear_active(execlists, EXECLISTS_ACTIVE_USER);
+       execlists_user_end(execlists);
 }
 
 static void clear_gtiir(struct intel_engine_cs *engine)
@@ -873,7 +886,7 @@ static void execlists_submission_tasklet(unsigned long data)
 {
        struct intel_engine_cs * const engine = (struct intel_engine_cs *)data;
        struct intel_engine_execlists * const execlists = &engine->execlists;
-       struct execlist_port * const port = execlists->port;
+       struct execlist_port *port = execlists->port;
        struct drm_i915_private *dev_priv = engine->i915;
        bool fw = false;
 
@@ -1012,9 +1025,19 @@ static void execlists_submission_tasklet(unsigned long 
data)
 
                        GEM_BUG_ON(count == 0);
                        if (--count == 0) {
+                               /*
+                                * On the final event corresponding to the
+                                * submission of this context, we expect either
+                                * an element-switch event or a completion
+                                * event (and on completion, the active-idle
+                                * marker). No more preemptions, lite-restore
+                                * or otherwise
+                                */
                                GEM_BUG_ON(status & GEN8_CTX_STATUS_PREEMPTED);
                                GEM_BUG_ON(port_isset(&port[1]) &&
                                           !(status & 
GEN8_CTX_STATUS_ELEMENT_SWITCH));
+                               GEM_BUG_ON(!port_isset(&port[1]) &&
+                                          !(status & 
GEN8_CTX_STATUS_ACTIVE_IDLE));
                                GEM_BUG_ON(!i915_request_completed(rq));
                                execlists_context_schedule_out(rq);
                                trace_i915_request_out(rq);
@@ -1023,17 +1046,14 @@ static void execlists_submission_tasklet(unsigned long 
data)
                                GEM_TRACE("%s completed ctx=%d\n",
                                          engine->name, port->context_id);
 
-                               execlists_port_complete(execlists, port);
+                               port = execlists_port_complete(execlists, port);
+                               if (port_isset(port))
+                                       execlists_user_begin(execlists, port);
+                               else
+                                       execlists_user_end(execlists);
                        } else {
                                port_set(port, port_pack(rq, count));
                        }
-
-                       /* After the final element, the hw should be idle */
-                       GEM_BUG_ON(port_count(port) == 0 &&
-                                  !(status & GEN8_CTX_STATUS_ACTIVE_IDLE));
-                       if (port_count(port) == 0)
-                               execlists_clear_active(execlists,
-                                                      EXECLISTS_ACTIVE_USER);
                }
 
                if (head != execlists->csb_head) {
diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.h 
b/drivers/gpu/drm/i915/intel_ringbuffer.h
index a02c7b3b9d55..2e20627e254b 100644
--- a/drivers/gpu/drm/i915/intel_ringbuffer.h
+++ b/drivers/gpu/drm/i915/intel_ringbuffer.h
@@ -638,6 +638,13 @@ execlists_set_active(struct intel_engine_execlists 
*execlists,
        __set_bit(bit, (unsigned long *)&execlists->active);
 }
 
+static inline bool
+execlists_set_active_once(struct intel_engine_execlists *execlists,
+                         unsigned int bit)
+{
+       return !__test_and_set_bit(bit, (unsigned long *)&execlists->active);
+}
+
 static inline void
 execlists_clear_active(struct intel_engine_execlists *execlists,
                       unsigned int bit)
@@ -664,7 +671,7 @@ execlists_num_ports(const struct intel_engine_execlists * 
const execlists)
        return execlists->port_mask + 1;
 }
 
-static inline void
+static inline struct execlist_port *
 execlists_port_complete(struct intel_engine_execlists * const execlists,
                        struct execlist_port * const port)
 {
@@ -675,6 +682,8 @@ execlists_port_complete(struct intel_engine_execlists * 
const execlists,
 
        memmove(port, port + 1, m * sizeof(struct execlist_port));
        memset(port + m, 0, sizeof(struct execlist_port));
+
+       return port;
 }
 
 static inline unsigned int
-- 
2.16.3

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