gpu: nvgpu: create sync_fence only if needed

Currently, we create sync_fence (from nvhost_sync_create_fence())
for every submit
But not all submits request for a sync_fence.

Also, nvhost_sync_create_fence() API takes about 1/3rd of the total
submit path.

Hence to optimize, we can allocate sync_fence
only when user explicitly asks for it using
(NVGPU_SUBMIT_GPFIFO_FLAGS_FENCE_GET &&
NVGPU_SUBMIT_GPFIFO_FLAGS_SYNC_FENCE)

Also, in CDE path from gk20a_prepare_compressible_read(),
we reuse existing fence stored in "state" and that can
result into not returning sync_fence_fd when user asked
for it
Hence, force allocation of sync_fence when job submission
comes from CDE path

Bug 200141116

Change-Id: Ia921701bf0e2432d6b8a5e8b7d91160e7f52db1e
Signed-off-by: Deepak Nibade <dnibade@nvidia.com>
Reviewed-on: http://git-master/r/812845
(cherry picked from commit 5fd47015eeed00352cc8473eff969a66c94fee98)
Reviewed-on: http://git-master/r/837662
Reviewed-by: Automatic_Commit_Validation_User
GVS: Gerrit_Virtual_Submit
Reviewed-by: Sachin Nikam <snikam@nvidia.com>

1 files changed, 5 insertions, 3 deletions

diff --git a/drivers/gpu/nvgpu/gk20a/channel_sync_gk20a.h b/drivers/gpu/nvgpu/gk20a/channel_sync_gk20a.h
index a347cbab..618e1b26 100644
--- a/drivers/gpu/nvgpu/gk20a/channel_sync_gk20a.h
+++ b/drivers/gpu/nvgpu/gk20a/channel_sync_gk20a.h
@@ -3,7 +3,7 @@
  *
  * GK20A Channel Synchronization Abstraction
  *
- * Copyright (c) 2014, NVIDIA CORPORATION.  All rights reserved.
+ * Copyright (c) 2014-2015, NVIDIA CORPORATION.  All rights reserved.
  *
  * This program is free software; you can redistribute it and/or modify it
  * under the terms and conditions of the GNU General Public License,
@@ -54,7 +54,8 @@ struct gk20a_channel_sync {
          */
         int (*incr)(struct gk20a_channel_sync *s,
                     struct priv_cmd_entry **entry,
-                    struct gk20a_fence **fence);
+                    struct gk20a_fence **fence,
+                    bool need_sync_fence);
 
         /* Increment syncpoint/semaphore, preceded by a wfi.
          * Returns
@@ -76,7 +77,8 @@ struct gk20a_channel_sync {
                          int wait_fence_fd,
                          struct priv_cmd_entry **entry,
                          struct gk20a_fence **fence,
-                         bool wfi);
+                         bool wfi,
+                         bool need_sync_fence);
 
         /* Reset the channel syncpoint/semaphore. */
         void (*set_min_eq_max)(struct gk20a_channel_sync *s);