[PATCH v3 8/9] 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 can't be entered during video
playback because there are not enough idle frames in a row to meet
most PSR2 panel deep sleep entry requirement typically 4 frames.
Hence switch to DC3CO when there is an update to display and switch
back to DC5 when display is idle. It is safer to allow DC5 after 6
idle frame, as PSR2 requires 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 dropping it, dc5_idle_thread() checks the valid wakeref before
    putting the reference count, which avoids any chances of dropping
    a zero wakeref. [Imre (IRC)]

Cc: Nikula, Jani <jani.nikula@intel.com>
Cc: Deak, Imre <imre.deak@intel.com>
Cc: Manna, Animesh <animesh.manna@intel.com>
Signed-off-by: Anshuman Gupta <anshuman.gupta@intel.com>
---
 drivers/gpu/drm/i915/display/intel_display.c  |  4 ++
 .../drm/i915/display/intel_display_power.c    | 72 +++++++++++++++++++
 .../drm/i915/display/intel_display_power.h    |  5 ++
 drivers/gpu/drm/i915/i915_drv.h               |  1 +
 4 files changed, 82 insertions(+)

diff --git a/drivers/gpu/drm/i915/display/intel_display.c b/drivers/gpu/drm/i915/display/intel_display.c
index 34a1867cd803..e8cc98757880 100644
--- a/drivers/gpu/drm/i915/display/intel_display.c
+++ b/drivers/gpu/drm/i915/display/intel_display.c
@@ -14083,6 +14083,8 @@ static void intel_atomic_commit_tail(struct intel_atomic_state *state)
 		intel_uncore_arm_unclaimed_mmio_detection(&dev_priv->uncore);
 		intel_display_power_put(dev_priv, POWER_DOMAIN_MODESET, wakeref);
 	}
+
+	tgl_switch_to_dc3co_after_flip(dev_priv);
 	intel_runtime_pm_put(&dev_priv->runtime_pm, state->wakeref);
 
 	/*
@@ -16157,6 +16159,7 @@ 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);
 
@@ -17100,6 +17103,7 @@ void intel_modeset_driver_remove(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 24df21e86a38..c44bef4b907d 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);
@@ -825,6 +826,41 @@ void tgl_enable_psr2_transcoder_exitline(struct intel_crtc_state  *cstate)
 	I915_WRITE(EXITLINE(cstate->cpu_transcoder), val);
 }
 
+void tgl_switch_to_dc3co_after_flip(struct drm_i915_private *dev_priv)
+{
+	struct intel_crtc *crtc;
+	struct intel_crtc_state *cstate;
+	u32 delay;
+
+	/* PSR2 is enabled and only edp is connected */
+	if (dev_priv->csr.prefer_dc3co && dev_priv->psr.psr2_enabled &&
+	    dev_priv->psr.enabled) {
+		/*
+		 * 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));
+	}
+}
+
 static bool tgl_is_only_edp_connected(struct intel_crtc_state  *crtc_state)
 {
 	struct drm_atomic_state *state = crtc_state->base.state;
@@ -889,6 +925,20 @@ 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);
@@ -1164,6 +1214,27 @@ 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)
 {
@@ -4234,6 +4305,7 @@ 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 1dd221c4bee1..43fb4bebba95 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;
@@ -237,6 +239,8 @@ 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);
@@ -259,6 +263,7 @@ void bxt_display_core_uninit(struct drm_i915_private *dev_priv);
 void tgl_prefer_dc3co_over_dc5_check(struct drm_i915_private *dev_priv,
 				     struct intel_atomic_state *state);
 void tgl_enable_psr2_transcoder_exitline(struct intel_crtc_state  *cstate);
+void tgl_switch_to_dc3co_after_flip(struct drm_i915_private *dev_priv);
 
 const char *
 intel_display_power_domain_str(struct drm_i915_private *i915,
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 8b7dbaa91a0d..0e07338de6db 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -359,6 +359,7 @@ 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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