gpu: nvgpu: rework private command buffer free path

We currently allocate private command buffers (wait_cmd
and incr_cmd) before submitting the job but we never
free them explicitly.
When private command queue of the channel is full, we
then try to recycle/remove free command buffers.
But this recycling happens during submit path, and
hence that particular submit path takes much longer

Rework this as below :
- add reference of command buffers to job structure
- when job completes, free the command buffers
  explicitly
- remove the code to recycle buffers since it should
  not be needed now

Note that command buffers need to be freed in order of
their allocation. Ensure this with error print before
freeing the command buffer entry

Bug 200141116
Bug 1698667

Change-Id: Id4b69429d7ad966307e0d122a71ad55076684307
Signed-off-by: Deepak Nibade <dnibade@nvidia.com>
Reviewed-on: http://git-master/r/827638
(cherry picked from commit c6cefd69b71c9b70d6df5343b13dfcfb3fa99598)
Reviewed-on: http://git-master/r/835802
Reviewed-by: Terje Bergstrom <tbergstrom@nvidia.com>
Tested-by: Terje Bergstrom <tbergstrom@nvidia.com>

1 files changed, 0 insertions, 2 deletions

diff --git a/drivers/gpu/nvgpu/gk20a/mm_gk20a.h b/drivers/gpu/nvgpu/gk20a/mm_gk20a.h
index 2dd4ccf5..ac55e988 100644
--- a/drivers/gpu/nvgpu/gk20a/mm_gk20a.h
+++ b/drivers/gpu/nvgpu/gk20a/mm_gk20a.h
@@ -160,8 +160,6 @@ struct priv_cmd_queue {
         u32 size;       /* num of entries in words */
         u32 put;        /* put for priv cmd queue */
         u32 get;        /* get for priv cmd queue */
-        struct list_head free;  /* list of pre-allocated free entries */
-        struct list_head head;  /* list of used entries */
 };
 
 struct priv_cmd_entry {