gpu: nvgpu: Remove unnecessary use of ACCESS_ONCE()

ACCESS_ONCE() is used for making sure that in a given place of code
access a variable exactly once. It prevents compiler rearranging the
read from happening earlier.

Remove its use from cases where rearranging of the read does not
create problems.

Change-Id: I340f375e8fecc31f3a3fab543256069cb4c682dc
Signed-off-by: Terje Bergstrom <tbergstrom@nvidia.com>
Reviewed-on: https://git-master.nvidia.com/r/1531649
GVS: Gerrit_Virtual_Submit
Reviewed-by: Alex Waterman <alexw@nvidia.com>

2 files changed, 6 insertions, 12 deletions

diff --git a/drivers/gpu/nvgpu/common/pmu/pmu_pg.c b/drivers/gpu/nvgpu/common/pmu/pmu_pg.c
index 3cdeedcc..ca74f243 100644
--- a/drivers/gpu/nvgpu/common/pmu/pmu_pg.c
+++ b/drivers/gpu/nvgpu/common/pmu/pmu_pg.c
@@ -206,7 +206,7 @@ int nvgpu_pmu_enable_elpg(struct gk20a *g)
                 pg_engine_id++) {
 
                 if (pg_engine_id == PMU_PG_ELPG_ENGINE_ID_MS &&
-                        ACCESS_ONCE(pmu->mscg_stat) == PMU_MSCG_DISABLED)
+                        pmu->mscg_stat == PMU_MSCG_DISABLED)
                         continue;
 
                 if (BIT(pg_engine_id) & pg_engine_id_list)
@@ -281,7 +281,7 @@ int nvgpu_pmu_disable_elpg(struct gk20a *g)
                 pg_engine_id++) {
 
                 if (pg_engine_id == PMU_PG_ELPG_ENGINE_ID_MS &&
-                        ACCESS_ONCE(pmu->mscg_stat) == PMU_MSCG_DISABLED)
+                        pmu->mscg_stat == PMU_MSCG_DISABLED)
                         continue;
 
                 if (BIT(pg_engine_id) & pg_engine_id_list) {
diff --git a/drivers/gpu/nvgpu/lpwr/lpwr.c b/drivers/gpu/nvgpu/lpwr/lpwr.c
index c80ddee0..b1189590 100644
--- a/drivers/gpu/nvgpu/lpwr/lpwr.c
+++ b/drivers/gpu/nvgpu/lpwr/lpwr.c
@@ -352,11 +352,8 @@ int nvgpu_lpwr_enable_pg(struct gk20a *g, bool pstate_lock)
         is_mscg_supported = nvgpu_lpwr_is_mscg_supported(g,
                         present_pstate);
         if (is_mscg_supported && g->mscg_enabled) {
-                if (!ACCESS_ONCE(pmu->mscg_stat)) {
-                        WRITE_ONCE(pmu->mscg_stat, PMU_MSCG_ENABLED);
-                        /* make status visible */
-                        smp_mb();
-                }
+                if (!pmu->mscg_stat)
+                        pmu->mscg_stat = PMU_MSCG_ENABLED;
         }
 
         is_rppg_supported = nvgpu_lpwr_is_rppg_supported(g,
@@ -402,11 +399,8 @@ int nvgpu_lpwr_disable_pg(struct gk20a *g, bool pstate_lock)
         is_mscg_supported = nvgpu_lpwr_is_mscg_supported(g,
                         present_pstate);
         if (is_mscg_supported && g->mscg_enabled) {
-                if (ACCESS_ONCE(pmu->mscg_stat)) {
-                        WRITE_ONCE(pmu->mscg_stat, PMU_MSCG_DISABLED);
-                        /* make status visible */
-                        smp_mb();
-                }
+                if (pmu->mscg_stat)
+                        pmu->mscg_stat = PMU_MSCG_DISABLED;
         }
 
 exit_unlock: