Ring switches can occur many times per frame, and are often out of
control, causing frequent RPS boosting for no practical benefit. Treat
the sw semaphore synchronisation as a separate client and only allow it
to boost once per busy/idle cycle.

Signed-off-by: Chris Wilson <ch...@chris-wilson.co.uk>
---
 drivers/gpu/drm/i915/i915_debugfs.c |  1 +
 drivers/gpu/drm/i915/i915_drv.h     | 34 ++++++++++++++++++----------------
 drivers/gpu/drm/i915/i915_gem.c     |  7 +++++--
 drivers/gpu/drm/i915/intel_pm.c     |  1 +
 4 files changed, 25 insertions(+), 18 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_debugfs.c 
b/drivers/gpu/drm/i915/i915_debugfs.c
index 5da74b46e202..c8fe548af41d 100644
--- a/drivers/gpu/drm/i915/i915_debugfs.c
+++ b/drivers/gpu/drm/i915/i915_debugfs.c
@@ -2296,6 +2296,7 @@ static int i915_rps_boost_info(struct seq_file *m, void 
*data)
                           list_empty(&file_priv->rps_boost) ? "" : ", active");
                rcu_read_unlock();
        }
+       seq_printf(m, "Semaphore boosts: %d\n", 
dev_priv->rps.semaphores.rps_boosts);
        seq_printf(m, "Kernel boosts: %d\n", dev_priv->rps.boosts);
 
        mutex_unlock(&dev_priv->rps.hw_lock);
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index d35778797ef0..057a1346e81f 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -268,6 +268,22 @@ struct drm_i915_private;
 struct i915_mm_struct;
 struct i915_mmu_object;
 
+struct drm_i915_file_private {
+       struct drm_i915_private *dev_priv;
+       struct drm_file *file;
+
+       struct {
+               spinlock_t lock;
+               struct list_head request_list;
+       } mm;
+       struct idr context_idr;
+
+       struct list_head rps_boost;
+       struct intel_engine_cs *bsd_ring;
+
+       unsigned rps_boosts;
+};
+
 enum intel_dpll_id {
        DPLL_ID_PRIVATE = -1, /* non-shared dpll in use */
        /* real shared dpll ids must be >= 0 */
@@ -1047,6 +1063,8 @@ struct intel_gen6_power_mgmt {
        struct list_head clients;
        unsigned boosts;
 
+       struct drm_i915_file_private semaphores;
+
        /* manual wa residency calculations */
        struct intel_rps_ei up_ei, down_ei;
 
@@ -2185,22 +2203,6 @@ static inline void i915_gem_request_assign(struct 
drm_i915_gem_request **pdst,
  * a later patch when the call to i915_seqno_passed() is obsoleted...
  */
 
-struct drm_i915_file_private {
-       struct drm_i915_private *dev_priv;
-       struct drm_file *file;
-
-       struct {
-               spinlock_t lock;
-               struct list_head request_list;
-       } mm;
-       struct idr context_idr;
-
-       struct list_head rps_boost;
-       struct intel_engine_cs *bsd_ring;
-
-       unsigned rps_boosts;
-};
-
 /*
  * A command that requires special handling by the command parser.
  */
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index a32a84598fac..3d31ff11fbef 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -3045,9 +3045,12 @@ __i915_gem_object_sync(struct drm_i915_gem_object *obj,
                return ret;
 
        if (!i915_semaphore_is_enabled(obj->base.dev)) {
+               struct drm_i915_private *i915 = to_i915(obj->base.dev);
                ret = __i915_wait_request(rq,
-                                         
atomic_read(&to_i915(obj->base.dev)->gpu_error.reset_counter),
-                                         
to_i915(obj->base.dev)->mm.interruptible, NULL, NULL);
+                                         
atomic_read(&i915->gpu_error.reset_counter),
+                                         i915->mm.interruptible,
+                                         NULL,
+                                         &i915->rps.semaphores);
                if (ret)
                        return ret;
 
diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
index d3f4e9593db1..3e274cf3adaa 100644
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -6827,6 +6827,7 @@ void intel_pm_setup(struct drm_device *dev)
        INIT_DELAYED_WORK(&dev_priv->rps.delayed_resume_work,
                          intel_gen6_powersave_work);
        INIT_LIST_HEAD(&dev_priv->rps.clients);
+       INIT_LIST_HEAD(&dev_priv->rps.semaphores.rps_boost);
 
        dev_priv->pm.suspended = false;
 }
-- 
2.1.4

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