gpu: nvgpu: gk20a: add busy lock

- add rw_semaphore busy_lock for gpu busy() path
- take read lock on busy_lock inside gk20a_busy()
  so that all usual requests can execute simultaneously
- write lock can be taken when we need to block all
  of the gk20a_busy() calls

Bug 1487804

Change-Id: I1b162b38bce9621723d3e45280c6076816cf771a
Signed-off-by: Deepak Nibade <dnibade@nvidia.com>
Reviewed-on: http://git-master/r/412060
Reviewed-by: Terje Bergstrom <tbergstrom@nvidia.com>
Tested-by: Terje Bergstrom <tbergstrom@nvidia.com>

1 files changed, 2 insertions, 0 deletions

diff --git a/drivers/gpu/nvgpu/gk20a/gk20a.h b/drivers/gpu/nvgpu/gk20a/gk20a.h
index ef7945f4..e6630ebf 100644
--- a/drivers/gpu/nvgpu/gk20a/gk20a.h
+++ b/drivers/gpu/nvgpu/gk20a/gk20a.h
@@ -220,6 +220,8 @@ struct gk20a {
 
         bool power_on;
 
+        struct rw_semaphore busy_lock;
+
         struct clk_gk20a clk;
         struct fifo_gk20a fifo;
         struct gr_gk20a gr;