gpu: nvgpu: implement sync refcounting

We currently free sync when we find job list empty
If aggressive_sync is set to true, we try to free
sync during channel unbind() call

But we rarely free sync from channel_unbind() call
since freeing it when job list is empty is
aggressive enough

Hence remove sync free code from channel_unbind()

Implement refcounting for sync:
- get a refcount while submitting a job (and
  allocate sync if it is not allocated already)
- put a refcount while freeing the job
- if refcount==0 and if aggressive_sync_destroy is
  set, free the sync
- if aggressive_sync_destroy is not set, we will
  free the sync during channel close time

Bug 200187553

Change-Id: I74e24adb15dc26a375ebca1fdd017b3ad6d57b61
Signed-off-by: Deepak Nibade <dnibade@nvidia.com>
Reviewed-on: http://git-master/r/1120410
Reviewed-by: Terje Bergstrom <tbergstrom@nvidia.com>
Tested-by: Terje Bergstrom <tbergstrom@nvidia.com>

4 files changed, 23 insertions, 45 deletions

diff --git a/drivers/gpu/nvgpu/gk20a/channel_gk20a.c b/drivers/gpu/nvgpu/gk20a/channel_gk20a.c
index aeb115ef..b282db89 100644
--- a/drivers/gpu/nvgpu/gk20a/channel_gk20a.c
+++ b/drivers/gpu/nvgpu/gk20a/channel_gk20a.c
@@ -370,7 +370,6 @@ static void channel_gk20a_bind(struct channel_gk20a *c)
 void channel_gk20a_unbind(struct channel_gk20a *ch_gk20a)
 {
         struct gk20a *g = ch_gk20a->g;
-        struct gk20a_platform *platform = gk20a_get_platform(g->dev);
 
         gk20a_dbg_fn("");
 
@@ -380,18 +379,6 @@ void channel_gk20a_unbind(struct channel_gk20a *ch_gk20a)
                         ccsr_channel_inst_bind_false_f());
 
         ch_gk20a->bound = false;
-
-        /*
-         * if we are agrressive then we can destroy the syncpt
-         * resource at this point
-         * if not, then it will be destroyed at channel_free()
-         */
-        mutex_lock(&ch_gk20a->sync_lock);
-        if (ch_gk20a->sync && platform->aggressive_sync_destroy) {
-                ch_gk20a->sync->destroy(ch_gk20a->sync);
-                ch_gk20a->sync = NULL;
-        }
-        mutex_unlock(&ch_gk20a->sync_lock);
 }
 
 int channel_gk20a_alloc_inst(struct gk20a *g, struct channel_gk20a *ch)
@@ -954,7 +941,7 @@ static void gk20a_free_channel(struct channel_gk20a *ch)
         /* sync must be destroyed before releasing channel vm */
         mutex_lock(&ch->sync_lock);
         if (ch->sync) {
-                ch->sync->destroy(ch->sync);
+                gk20a_channel_sync_destroy(ch->sync);
                 ch->sync = NULL;
         }
         mutex_unlock(&ch->sync_lock);
@@ -1922,8 +1909,18 @@ static void gk20a_channel_clean_up_jobs(struct work_struct *work)
 
                 gk20a_channel_timeout_stop(c);
 
-                if (c->sync)
+                mutex_lock(&c->sync_lock);
+                if (c->sync) {
                         c->sync->signal_timeline(c->sync);
+                        if (atomic_dec_and_test(&c->sync->refcount) &&
+                                        platform->aggressive_sync_destroy) {
+                                gk20a_channel_sync_destroy(c->sync);
+                                c->sync = NULL;
+                        }
+                } else {
+                        WARN_ON(1);
+                }
+                mutex_unlock(&c->sync_lock);
 
                 if (job->num_mapped_buffers)
                         gk20a_vm_put_buffers(vm, job->mapped_buffers,
@@ -1950,23 +1947,6 @@ static void gk20a_channel_clean_up_jobs(struct work_struct *work)
                 gk20a_idle(g->dev);
         }
 
-        /*
-         * If job list is empty then channel is idle and we can free
-         * the syncpt here (given aggressive_destroy flag is set)
-         * Note: check if last submit is complete before destroying
-         * the sync resource
-         */
-        if (list_empty(&c->jobs)) {
-                mutex_lock(&c->sync_lock);
-                mutex_lock(&c->last_submit.fence_lock);
-                if (c->sync && platform->aggressive_sync_destroy &&
-                          gk20a_fence_is_expired(c->last_submit.post_fence)) {
-                        c->sync->destroy(c->sync);
-                        c->sync = NULL;
-                }
-                mutex_unlock(&c->last_submit.fence_lock);
-                mutex_unlock(&c->sync_lock);
-        }
         mutex_unlock(&c->jobs_lock);
         mutex_unlock(&c->submit_lock);
 
@@ -2121,6 +2101,7 @@ int gk20a_submit_channel_gpfifo(struct channel_gk20a *c,
                 }
                 new_sync_created = true;
         }
+        atomic_inc(&c->sync->refcount);
         mutex_unlock(&c->sync_lock);
 
         if (g->ops.fifo.resetup_ramfc && new_sync_created) {
diff --git a/drivers/gpu/nvgpu/gk20a/channel_sync_gk20a.c b/drivers/gpu/nvgpu/gk20a/channel_sync_gk20a.c
index 025b000e..b47c1010 100644
--- a/drivers/gpu/nvgpu/gk20a/channel_sync_gk20a.c
+++ b/drivers/gpu/nvgpu/gk20a/channel_sync_gk20a.c
@@ -356,6 +356,7 @@ gk20a_channel_syncpt_create(struct channel_gk20a *c)
 
         nvhost_syncpt_set_min_eq_max_ext(sp->host1x_pdev, sp->id);
 
+        atomic_set(&sp->ops.refcount, 0);
         sp->ops.wait_syncpt             = gk20a_channel_syncpt_wait_syncpt;
         sp->ops.wait_fd                 = gk20a_channel_syncpt_wait_fd;
         sp->ops.incr                    = gk20a_channel_syncpt_incr;
@@ -711,6 +712,7 @@ gk20a_channel_semaphore_create(struct channel_gk20a *c)
         if (!sema->timeline)
                 goto clean_up;
 #endif
+        atomic_set(&sema->ops.refcount, 0);
         sema->ops.wait_syncpt   = gk20a_channel_semaphore_wait_syncpt;
         sema->ops.wait_fd       = gk20a_channel_semaphore_wait_fd;
         sema->ops.incr          = gk20a_channel_semaphore_incr;
@@ -727,6 +729,11 @@ clean_up:
         return NULL;
 }
 
+void gk20a_channel_sync_destroy(struct gk20a_channel_sync *sync)
+{
+        sync->destroy(sync);
+}
+
 struct gk20a_channel_sync *gk20a_channel_sync_create(struct channel_gk20a *c)
 {
 #ifdef CONFIG_TEGRA_GK20A
diff --git a/drivers/gpu/nvgpu/gk20a/channel_sync_gk20a.h b/drivers/gpu/nvgpu/gk20a/channel_sync_gk20a.h
index 618e1b26..4b0918de 100644
--- a/drivers/gpu/nvgpu/gk20a/channel_sync_gk20a.h
+++ b/drivers/gpu/nvgpu/gk20a/channel_sync_gk20a.h
@@ -27,6 +27,8 @@ struct gk20a_semaphore;
 struct gk20a_fence;
 
 struct gk20a_channel_sync {
+        atomic_t refcount;
+
         /* Generate a gpu wait cmdbuf from syncpoint.
          * Returns
          *  - a gpu cmdbuf that performs the wait when executed,
@@ -91,13 +93,11 @@ struct gk20a_channel_sync {
         /* Returns the sync point id or negative number if no syncpt*/
         int (*syncpt_id)(struct gk20a_channel_sync *s);
 
-        /* flag to set sync destroy aggressiveness */
-        bool aggressive_destroy;
-
         /* Free the resources allocated by gk20a_channel_sync_create. */
         void (*destroy)(struct gk20a_channel_sync *s);
 };
 
+void gk20a_channel_sync_destroy(struct gk20a_channel_sync *sync);
 struct gk20a_channel_sync *gk20a_channel_sync_create(struct channel_gk20a *c);
 
 #endif
diff --git a/drivers/gpu/nvgpu/vgpu/fifo_vgpu.c b/drivers/gpu/nvgpu/vgpu/fifo_vgpu.c
index 535de851..294581b9 100644
--- a/drivers/gpu/nvgpu/vgpu/fifo_vgpu.c
+++ b/drivers/gpu/nvgpu/vgpu/fifo_vgpu.c
@@ -59,16 +59,6 @@ static void vgpu_channel_unbind(struct channel_gk20a *ch)
         }
 
         ch->bound = false;
-
-        /*
-         * if we are agrressive then we can destroy the syncpt
-         * resource at this point
-         * if not, then it will be destroyed at channel_free()
-         */
-        if (ch->sync && platform->aggressive_sync_destroy) {
-                ch->sync->destroy(ch->sync);
-                ch->sync = NULL;
-        }
 }
 
 static int vgpu_channel_alloc_inst(struct gk20a *g, struct channel_gk20a *ch)