[Intel-gfx] [PATCH v3] drm/i915: Debugfs disable RPS boost and idle

[Daisy Sun]

RP frequency request is affected by 2 modules: normal turbo
algorithm and RPS boost algorithm. By adding RPS boost algorithm
to the mix, the final frequency becomes relatively unpredictable.
Add a switch to enable/disable RPS boost functionality. When
disabled, RP frequency will follow the normal turbo algorithm only.

Intention: when boost and idle are disabled, we have a clear vision
of turbo algorithm. It‘s very helpful to verify if the turbo
algorithm is working as expected.
Without debugfs hooks, the RPS boost or idle may kick in at
anytime and any circumstances.

V1->V2: Follow Daniel's comment to explain the intention.
V2->V3: Abandon flush_delayed work, abandon lock of rps.hw_lock
during get/set of rps.debugfs_disable_boost

Signed-off-by: Daisy Sun <daisy.sun at intel.com>
---
 drivers/gpu/drm/i915/i915_debugfs.c | 29 +++++++++++++++++++++++++++++
 drivers/gpu/drm/i915/i915_drv.h     |  1 +
 drivers/gpu/drm/i915/intel_pm.c     |  8 ++++++--
 3 files changed, 36 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c
index 1e83ae4..685f7e5 100644
--- a/drivers/gpu/drm/i915/i915_debugfs.c
+++ b/drivers/gpu/drm/i915/i915_debugfs.c
@@ -3486,6 +3486,34 @@ DEFINE_SIMPLE_ATTRIBUTE(i915_drop_caches_fops,
 			i915_drop_caches_get, i915_drop_caches_set,
 			"0x%08llx\n");
 
+static int i915_rps_disable_boost_get(void *data, u64 *val)
+{
+	struct drm_device *dev = data;
+	struct drm_i915_private *dev_priv = dev->dev_private;
+
+	*val = dev_priv->rps.debugfs_disable_boost;
+
+	return 0;
+}
+
+static int i915_rps_disable_boost_set(void *data, u64 val)
+{
+	struct drm_device *dev = data;
+	struct drm_i915_private *dev_priv = dev->dev_private;
+	int ret;
+
+	DRM_DEBUG_DRIVER("%s RPS Boost-Idle mode\n",
+				 val ? "Disable" : "Enable");
+
+	dev_priv->rps.debugfs_disable_boost = val;
+
+	return 0;
+}
+
+DEFINE_SIMPLE_ATTRIBUTE(i915_rps_disable_boost_fops,
+		i915_rps_disable_boost_get, i915_rps_disable_boost_set,
+			"%llu\n");
+
 static int
 i915_max_freq_get(void *data, u64 *val)
 {
@@ -3821,6 +3849,7 @@ static const struct i915_debugfs_files {
 	{"i915_wedged", &i915_wedged_fops},
 	{"i915_max_freq", &i915_max_freq_fops},
 	{"i915_min_freq", &i915_min_freq_fops},
+	{"i915_rps_disable_boost", &i915_rps_disable_boost_fops},
 	{"i915_cache_sharing", &i915_cache_sharing_fops},
 	{"i915_ring_stop", &i915_ring_stop_fops},
 	{"i915_ring_missed_irq", &i915_ring_missed_irq_fops},
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 272aa7a..9c427da 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -847,6 +847,7 @@ struct intel_gen6_power_mgmt {
 	int last_adj;
 	enum { LOW_POWER, BETWEEN, HIGH_POWER } power;
 
+	bool debugfs_disable_boost;
 	bool enabled;
 	struct delayed_work delayed_resume_work;
 
diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
index 75c1c76..6acac14 100644
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -3163,7 +3163,9 @@ void gen6_rps_idle(struct drm_i915_private *dev_priv)
 	struct drm_device *dev = dev_priv->dev;
 
 	mutex_lock(&dev_priv->rps.hw_lock);
-	if (dev_priv->rps.enabled) {
+
+	if (dev_priv->rps.enabled
+		&& !dev_priv->rps.debugfs_disable_boost) {
 		if (IS_VALLEYVIEW(dev))
 			vlv_set_rps_idle(dev_priv);
 		else
@@ -3178,7 +3180,9 @@ void gen6_rps_boost(struct drm_i915_private *dev_priv)
 	struct drm_device *dev = dev_priv->dev;
 
 	mutex_lock(&dev_priv->rps.hw_lock);
-	if (dev_priv->rps.enabled) {
+
+	if (dev_priv->rps.enabled
+		&& !dev_priv->rps.debugfs_disable_boost) {
 		if (IS_VALLEYVIEW(dev))
 			valleyview_set_rps(dev_priv->dev, dev_priv->rps.max_freq_softlimit);
 		else
-- 
1.9.1