[Intel-gfx] [PATCH 1/1] drm/i915: Add debugfs tunable for forcewake hysteresis

[Mika Kuoppala]

Add a tunable to set forcewake hysteresis timer for those
who want explore the perf/power impacts.

Signed-off-by: Mika Kuoppala <mika.kuoppala at intel.com>
---
 drivers/gpu/drm/i915/i915_debugfs.c | 44 +++++++++++++++++++++++++++++++++++++
 drivers/gpu/drm/i915/i915_drv.h     |  8 +++++++
 drivers/gpu/drm/i915/intel_uncore.c | 19 +++++++++++++++-
 3 files changed, 70 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c
index 2ad4c48..3c55d40 100644
--- a/drivers/gpu/drm/i915/i915_debugfs.c
+++ b/drivers/gpu/drm/i915/i915_debugfs.c
@@ -1301,6 +1301,9 @@ static int i915_forcewake_domains(struct seq_file *m, void *data)
 		seq_printf(m, "%s.wake_count = %u\n",
 			   intel_uncore_forcewake_domain_to_str(i),
 			   fw_domain->wake_count);
+		seq_printf(m, "%s.hyst_ms = %u\n",
+			   intel_uncore_forcewake_domain_to_str(i),
+			   jiffies_to_msecs(fw_domain->hyst_jiffies));
 	}
 	spin_unlock_irq(&dev_priv->uncore.lock);
 
@@ -4321,6 +4324,46 @@ DEFINE_SIMPLE_ATTRIBUTE(i915_cache_sharing_fops,
 			i915_cache_sharing_get, i915_cache_sharing_set,
 			"%llu\n");
 
+static int i915_forcewake_hysteresis_get(void *data, u64 *val)
+{
+	struct drm_device *dev = data;
+	struct drm_i915_private *dev_priv = dev->dev_private;
+	struct intel_uncore_forcewake_domain *d;
+	enum forcewake_domain_id id;
+
+	spin_lock_irq(&dev_priv->uncore.lock);
+	/* Same hysteresis for all */
+	for_each_fw_domain(d, dev_priv, id) {
+		*val = fw_domain_get_hysteresis(d);
+		break;
+	}
+	spin_unlock_irq(&dev_priv->uncore.lock);
+
+	return 0;
+}
+
+static int i915_forcewake_hysteresis_set(void *data, u64 val)
+{
+	struct drm_device *dev = data;
+	struct drm_i915_private *dev_priv = dev->dev_private;
+	struct intel_uncore_forcewake_domain *d;
+	enum forcewake_domain_id id;
+
+	spin_lock_irq(&dev_priv->uncore.lock);
+	/* Same hysteresis for all */
+	for_each_fw_domain(d, dev_priv, id)
+		fw_domain_set_hysteresis(d, val);
+
+	spin_unlock_irq(&dev_priv->uncore.lock);
+
+	return 0;
+}
+
+DEFINE_SIMPLE_ATTRIBUTE(i915_forcewake_hysteresis_fops,
+			i915_forcewake_hysteresis_get,
+			i915_forcewake_hysteresis_set,
+			"%llu\n");
+
 static int i915_forcewake_open(struct inode *inode, struct file *file)
 {
 	struct drm_device *dev = inode->i_private;
@@ -4455,6 +4498,7 @@ static const struct i915_debugfs_files {
 	{"i915_spr_wm_latency", &i915_spr_wm_latency_fops},
 	{"i915_cur_wm_latency", &i915_cur_wm_latency_fops},
 	{"i915_fbc_false_color", &i915_fbc_fc_fops},
+	{"i915_forcewake_hysteresis", &i915_forcewake_hysteresis_fops},
 };
 
 void intel_display_crc_init(struct drm_device *dev)
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 0d67b17..6b10dc1 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -630,6 +630,7 @@ struct intel_uncore {
 		enum forcewake_domain_id id;
 		unsigned wake_count;
 		struct timer_list timer;
+		unsigned long hyst_jiffies;
 		u32 reg_set;
 		u32 val_set;
 		u32 val_clear;
@@ -2578,6 +2579,13 @@ void intel_uncore_forcewake_put(struct drm_i915_private *dev_priv,
 void assert_forcewakes_inactive(struct drm_i915_private *dev_priv);
 
 void
+fw_domain_set_hysteresis(struct intel_uncore_forcewake_domain *d,
+			      unsigned hyst_ms);
+unsigned
+fw_domain_get_hysteresis(const struct intel_uncore_forcewake_domain *d);
+
+
+void
 i915_enable_pipestat(struct drm_i915_private *dev_priv, enum pipe pipe,
 		     u32 status_mask);
 
diff --git a/drivers/gpu/drm/i915/intel_uncore.c b/drivers/gpu/drm/i915/intel_uncore.c
index b3951f2..723698c 100644
--- a/drivers/gpu/drm/i915/intel_uncore.c
+++ b/drivers/gpu/drm/i915/intel_uncore.c
@@ -62,6 +62,22 @@ intel_uncore_forcewake_domain_to_str(const enum forcewake_domain_id id)
 	return "unknown";
 }
 
+void
+fw_domain_set_hysteresis(struct intel_uncore_forcewake_domain *d,
+			 unsigned hyst_ms)
+{
+	d->hyst_jiffies = msecs_to_jiffies_timeout(hyst_ms);
+
+	if (d->hyst_jiffies == 0)
+		d->hyst_jiffies = 1;
+}
+
+unsigned
+fw_domain_get_hysteresis(const struct intel_uncore_forcewake_domain *d)
+{
+	return jiffies_to_msecs(d->hyst_jiffies);
+}
+
 static void
 assert_device_not_suspended(struct drm_i915_private *dev_priv)
 {
@@ -78,7 +94,7 @@ fw_domain_reset(const struct intel_uncore_forcewake_domain *d)
 static inline void
 fw_domain_arm_timer(struct intel_uncore_forcewake_domain *d)
 {
-	mod_timer_pinned(&d->timer, jiffies + 1);
+	mod_timer_pinned(&d->timer, jiffies + d->hyst_jiffies);
 }
 
 static inline void
@@ -956,6 +972,7 @@ static void fw_domain_init(struct drm_i915_private *dev_priv,
 	WARN_ON(d->wake_count);
 
 	d->wake_count = 0;
+	d->hyst_jiffies = 1;
 	d->reg_set = reg_set;
 	d->reg_ack = reg_ack;
 
-- 
1.9.1