[PATCH v2 08/10] drm/i915/tgl:switch between dc3co and dc5 based on display idleness.

[Anshuman Gupta <anshuman.gupta@intel.com>]

DC5 and DC6 not allowed when DC3CO feature is enabled.

DC5 and DC6 saves more power, but cannot be entered during video
playback because there are not enough idle frames in a row to meet.
Most PSR2 panel deep sleep entry requirements typically 4 frames.

This patch switch to DC3CO when there is an update to display and it
switch to DC5 when display is idle.
It is safer to allow DC5 after 6 idle frame, as PSR2 required minimum
6 idle frame.

v2: calculated s/w state to switch over dc3co when there is an
    update. [Imre]
    used cancel_delayed_work_sync() in order to avoid any race
    with already scheduled delayed work. [Imre]
v3  cancel_delayed_work_sync() may blocked the commit work.
    Hence droping it, dc5_idle_thread() checks the valid wakeref before
    putting the reference count, which avoids any chances of droping
    a zero wakeref. [Imre (IRC)]
    Now there can be chances of existing scheduled delayed work may get
    run before 6 idle frames whilst an atomic commit, but that is
    harmless because DMC will enter DC3CO after PSR2 Selective update
    followed by PSR2 idle frame trigger during Video Playback and that
    will require more than one flip.

Cc: jani.nikula@intel.com
Cc: imre.deak@intel.com
Cc: animesh.manna@intel.com
Signed-off-by: Anshuman Gupta <anshuman.gupta@intel.com>
---
 drivers/gpu/drm/i915/display/intel_display.c  | 34 +++++++++++++++++
 .../drm/i915/display/intel_display_power.c    | 37 +++++++++++++++++++
 .../drm/i915/display/intel_display_power.h    |  4 ++
 drivers/gpu/drm/i915/i915_drv.h               |  1 +
 4 files changed, 76 insertions(+)

diff --git a/drivers/gpu/drm/i915/display/intel_display.c b/drivers/gpu/drm/i915/display/intel_display.c
index ff2865e94c4c..688cdb3296c2 100644
--- a/drivers/gpu/drm/i915/display/intel_display.c
+++ b/drivers/gpu/drm/i915/display/intel_display.c
@@ -14140,6 +14140,7 @@ static int intel_atomic_commit(struct drm_device *dev,
 	struct intel_atomic_state *intel_state = to_intel_atomic_state(state);
 	struct drm_i915_private *dev_priv = to_i915(dev);
 	int ret = 0;
+	u32 delay;
 
 	intel_state->wakeref = intel_runtime_pm_get(&dev_priv->runtime_pm);
 
@@ -14224,6 +14225,37 @@ static int intel_atomic_commit(struct drm_device *dev,
 			flush_workqueue(dev_priv->modeset_wq);
 		intel_atomic_commit_tail(intel_state);
 	}
+	/* PSR2 is enabled and only edp is connected */
+	if (dev_priv->csr.prefer_dc3co && dev_priv->psr.psr2_enabled &&
+	    dev_priv->psr.enabled) {
+		struct intel_crtc *crtc;
+		struct intel_crtc_state *cstate;
+
+		/*
+		 * As every flip go through intel_atomic_commit, so tracking a
+		 * atomic commit will be a hint for idle frames.
+		 * Delayed work for 6 idle frames will be enough to allow dc6
+		 * over dc3co for deepest power savings.
+		 * At every atomic commit cancel the delayed work first,
+		 * when delayed scheduled that means display has been idle
+		 * for the 6 idle frame.
+		 */
+		cancel_delayed_work(&dev_priv->csr.idle_work);
+		mutex_lock(&dev_priv->csr.dc5_mutex);
+		if (!dev_priv->csr.dc5_wakeref) {
+			dev_priv->csr.dc5_wakeref =
+			intel_display_power_get(dev_priv, POWER_DOMAIN_VIDEO);
+			tgl_psr2_deep_sleep_disable(dev_priv);
+		}
+		mutex_unlock(&dev_priv->csr.dc5_mutex);
+		crtc = intel_get_crtc_for_pipe(dev_priv, PIPE_A);
+		cstate = to_intel_crtc_state(crtc->base.state);
+
+		delay = DC5_REQ_IDLE_FRAMES * intel_get_frame_time_us(cstate);
+		schedule_delayed_work(&dev_priv->csr.idle_work,
+				      usecs_to_jiffies(delay));
+	}
+
 
 	return 0;
 }
@@ -16148,6 +16180,7 @@ int intel_modeset_init(struct drm_device *dev)
 	init_llist_head(&dev_priv->atomic_helper.free_list);
 	INIT_WORK(&dev_priv->atomic_helper.free_work,
 		  intel_atomic_helper_free_state_worker);
+	INIT_DELAYED_WORK(&dev_priv->csr.idle_work, intel_dc5_idle_thread);
 
 	intel_init_quirks(dev_priv);
 
@@ -17089,6 +17122,7 @@ void intel_modeset_cleanup(struct drm_device *dev)
 	flush_workqueue(dev_priv->modeset_wq);
 
 	flush_work(&dev_priv->atomic_helper.free_work);
+	flush_delayed_work(&dev_priv->csr.idle_work);
 	WARN_ON(!llist_empty(&dev_priv->atomic_helper.free_list));
 
 	/*
diff --git a/drivers/gpu/drm/i915/display/intel_display_power.c b/drivers/gpu/drm/i915/display/intel_display_power.c
index 9d29ee460c68..28edab5cb97e 100644
--- a/drivers/gpu/drm/i915/display/intel_display_power.c
+++ b/drivers/gpu/drm/i915/display/intel_display_power.c
@@ -19,6 +19,7 @@
 #include "intel_sideband.h"
 #include "intel_tc.h"
 #include "intel_pm.h"
+#include "intel_psr.h"
 
 bool intel_display_power_well_is_enabled(struct drm_i915_private *dev_priv,
 					 enum i915_power_well_id power_well_id);
@@ -883,6 +884,20 @@ void tgl_prefer_dc3co_over_dc5_check(struct drm_i915_private *dev_priv,
 	}
 }
 
+void intel_dc5_idle_thread(struct work_struct *work)
+{
+	intel_wakeref_t wakeref __maybe_unused;
+	struct drm_i915_private *dev_priv =
+		container_of(work, typeof(*dev_priv), csr.idle_work.work);
+
+	mutex_lock(&dev_priv->csr.dc5_mutex);
+	wakeref	= fetch_and_zero(&dev_priv->csr.dc5_wakeref);
+	if (wakeref)
+		intel_display_power_put(dev_priv, POWER_DOMAIN_VIDEO, wakeref);
+	tgl_psr2_deep_sleep_enable(dev_priv);
+	mutex_unlock(&dev_priv->csr.dc5_mutex);
+}
+
 static void tgl_allow_dc3co(struct drm_i915_private *dev_priv)
 {
 	gen9_set_dc_state(dev_priv, DC_STATE_EN_DC3CO);
@@ -1158,6 +1173,27 @@ static bool tgl_dc3co_power_well_enabled(struct drm_i915_private *dev_priv,
 		(I915_READ(DC_STATE_EN) & DC_STATE_EN_UPTO_DC5_DC6_MASK) == 0);
 }
 
+u32 intel_get_frame_time_us(const struct intel_crtc_state *cstate)
+{
+	u32 pixel_rate, crtc_htotal, crtc_vtotal;
+	uint_fixed_16_16_t frametime_us;
+
+	if (!cstate || !cstate->base.active)
+		return 0;
+
+	pixel_rate = cstate->pixel_rate;
+
+	if (WARN_ON(pixel_rate == 0))
+		return 0;
+
+	crtc_htotal = cstate->base.adjusted_mode.crtc_htotal;
+	crtc_vtotal = cstate->base.adjusted_mode.crtc_vtotal;
+	frametime_us = div_fixed16(crtc_htotal * crtc_vtotal * 1000,
+				   pixel_rate);
+
+	return fixed16_to_u32_round_up(frametime_us);
+}
+
 static void i9xx_power_well_sync_hw_noop(struct drm_i915_private *dev_priv,
 					 struct i915_power_well *power_well)
 {
@@ -4228,6 +4264,7 @@ int intel_power_domains_init(struct drm_i915_private *dev_priv)
 	BUILD_BUG_ON(POWER_DOMAIN_NUM > 64);
 
 	mutex_init(&power_domains->lock);
+	mutex_init(&dev_priv->csr.dc5_mutex);
 
 	INIT_DELAYED_WORK(&power_domains->async_put_work,
 			  intel_display_power_put_async_work);
diff --git a/drivers/gpu/drm/i915/display/intel_display_power.h b/drivers/gpu/drm/i915/display/intel_display_power.h
index 635b93cf67fd..2dd57c3bf383 100644
--- a/drivers/gpu/drm/i915/display/intel_display_power.h
+++ b/drivers/gpu/drm/i915/display/intel_display_power.h
@@ -10,6 +10,8 @@
 #include "intel_runtime_pm.h"
 #include "i915_reg.h"
 
+#define DC5_REQ_IDLE_FRAMES	6
+
 struct drm_i915_private;
 struct intel_encoder;
 struct intel_crtc_state;
@@ -236,6 +238,8 @@ struct i915_power_domains {
 
 void skl_enable_dc6(struct drm_i915_private *dev_priv);
 void gen9_sanitize_dc_state(struct drm_i915_private *dev_priv);
+void intel_dc5_idle_thread(struct work_struct *work);
+u32 intel_get_frame_time_us(const struct intel_crtc_state *cstate);
 void bxt_enable_dc9(struct drm_i915_private *dev_priv);
 void bxt_disable_dc9(struct drm_i915_private *dev_priv);
 void gen9_enable_dc5(struct drm_i915_private *dev_priv);
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 72bbc786053e..ae565661a095 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -358,6 +358,7 @@ struct intel_csr {
 	u32 mmiodata[20];
 	u32 dc_state;
 	u32 allowed_dc_mask;
+	struct delayed_work idle_work;
 	intel_wakeref_t wakeref;
 	bool prefer_dc3co;
 	intel_wakeref_t dc5_wakeref;
-- 
2.21.0

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