gpu: nvgpu: Add sw shadow for load value

Reading the load value may increase CPU power consumption
temprorarily. In most cases we are ok with a value that
was read a moment earlier.

This patch introduces a software shadow for gpu load. The shadow
is updated before starting scaling and all scaling code paths use
the sw shadow.

Change-Id: I53d2ccb8e7f83147f411a14d3104d890dd9af9a3
Signed-off-by: Arto Merilainen <amerilainen@nvidia.com>
Reviewed-on: http://git-master/r/453347
Reviewed-by: Automatic_Commit_Validation_User
Reviewed-by: Terje Bergstrom <tbergstrom@nvidia.com>

1 files changed, 8 insertions, 2 deletions

diff --git a/drivers/gpu/nvgpu/gk20a/pmu_gk20a.c b/drivers/gpu/nvgpu/gk20a/pmu_gk20a.c
index 7c441f53..06e7a4e6 100644
--- a/drivers/gpu/nvgpu/gk20a/pmu_gk20a.c
+++ b/drivers/gpu/nvgpu/gk20a/pmu_gk20a.c
@@ -3677,16 +3677,22 @@ int gk20a_pmu_destroy(struct gk20a *g)
 
 int gk20a_pmu_load_norm(struct gk20a *g, u32 *load)
 {
+        *load = g->pmu.load_shadow;
+        return 0;
+}
+
+int gk20a_pmu_load_update(struct gk20a *g)
+{
         struct pmu_gk20a *pmu = &g->pmu;
         u16 _load = 0;
 
         if (!pmu->perfmon_ready) {
-                *load = 0;
+                pmu->load_shadow = 0;
                 return 0;
         }
 
         pmu_copy_from_dmem(pmu, pmu->sample_buffer, (u8 *)&_load, 2, 0);
-        *load = _load / 10;
+        pmu->load_shadow = _load / 10;
 
         return 0;
 }