gpu: nvgpu: 3d.emc frequency scaling

o QoS notifier
  Refresh the gpu load query because we may update the emc target
  if gpu load changed.

o tegra_postscale()
  Scaling the emc clock to a new target may be necessary
  if the gpu load changed at low gpu frequencies.

Bug 1591643

Change-Id: Ibc6f73c02eaf6cedb7f0f579d5f4d90c735d354a
Signed-off-by: Anders Kugler <akugler@nvidia.com>
Reviewed-on: http://git-master/r/680929
Reviewed-by: Automatic_Commit_Validation_User
Reviewed-by: Arto Merilainen <amerilainen@nvidia.com>
Reviewed-by: Terje Bergstrom <tbergstrom@nvidia.com>
Reviewed-by: Yu-Huan Hsu <yhsu@nvidia.com>

1 files changed, 11 insertions, 5 deletions

diff --git a/drivers/gpu/nvgpu/gk20a/gk20a_scale.c b/drivers/gpu/nvgpu/gk20a/gk20a_scale.c
index 7efd07bf..c3affe83 100644
--- a/drivers/gpu/nvgpu/gk20a/gk20a_scale.c
+++ b/drivers/gpu/nvgpu/gk20a/gk20a_scale.c
@@ -1,7 +1,7 @@
 /*
  * gk20a clock scaling profile
  *
- * Copyright (c) 2013-2014, NVIDIA Corporation. All rights reserved.
+ * Copyright (c) 2013-2015, 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,
@@ -60,6 +60,9 @@ static int gk20a_scale_qos_notify(struct notifier_block *nb,
         if (g->devfreq)
                 freq = max(g->devfreq->previous_freq, freq);
 
+        /* Update gpu load because we may scale the emc target
+         * if the gpu load changed. */
+        gk20a_pmu_load_update(g);
         platform->postscale(profile->pdev, freq);
 
         return NOTIFY_OK;
@@ -107,15 +110,18 @@ static int gk20a_scale_target(struct device *dev, unsigned long *freq,
         struct gk20a_scale_profile *profile = g->scale_profile;
         unsigned long rounded_rate = gk20a_clk_round_rate(g, *freq);
 
-        if (gk20a_clk_get_rate(g) == rounded_rate) {
+        if (gk20a_clk_get_rate(g) == rounded_rate)
                 *freq = rounded_rate;
-                return 0;
+        else {
+                gk20a_clk_set_rate(g, rounded_rate);
+                *freq = gk20a_clk_get_rate(g);
         }
 
-        gk20a_clk_set_rate(g, rounded_rate);
+        /* postscale will only scale emc (dram clock) if evaluating
+         * gk20a_tegra_get_emc_rate() produces a new or different emc
+         * target because the load or_and gpufreq has changed */
         if (platform->postscale)
                 platform->postscale(profile->pdev, rounded_rate);
-        *freq = gk20a_clk_get_rate(g);
 
         return 0;
 }