+/**
+ * intel_edp_drrs_flush - Flush DRRS
+ * @dev: DRM device
+ * @frontbuffer_bits: frontbuffer plane tracking bits
+ *
+ * When there is no movement on screen, DRRS work can be scheduled.
+ * This DRRS work is responsible for setting relevant registers after a
+ * timeout of 1 second.
+ *
+ * Dirty frontbuffers relevant to DRRS are tracked in busy_frontbuffer_bits.
+ */
+void intel_edp_drrs_flush(struct drm_device *dev,
+ unsigned frontbuffer_bits)
+{
+ struct drm_i915_private *dev_priv = dev->dev_private;
+ struct drm_crtc *crtc;
+ enum pipe pipe;
+
+ if (!dev_priv->drrs.dp)
+ return;
+
+ mutex_lock(&dev_priv->drrs.mutex);
+ crtc = dp_to_dig_port(dev_priv->drrs.dp)->base.base.crtc;
+ pipe = to_intel_crtc(crtc)->pipe;
+ dev_priv->drrs.busy_frontbuffer_bits &= ~frontbuffer_bits;
+
+ cancel_delayed_work_sync(&dev_priv->drrs.work);
+
+ if (dev_priv->drrs.refresh_rate_type != DRRS_LOW_RR &&
+ !dev_priv->drrs.busy_frontbuffer_bits)
+ schedule_delayed_work(&dev_priv->drrs.work,
+ msecs_to_jiffies(1000));
+ mutex_unlock(&dev_priv->drrs.mutex);
+}
+
+/**
+ * DOC: Display Refresh Rate Switching (DRRS)
+ *
+ * Display Refresh Rate Switching (DRRS) is a power conservation feature
+ * which enables swtching between low and high refresh rates,
+ * dynamically, based on the usage scenario. This feature is applicable
+ * for internal panels.
+ *
+ * Indication that the panel supports DRRS is given by the panel EDID, which
+ * would list multiple refresh rates for one resolution.
+ *
+ * DRRS is of 2 types - static and seamless.
+ * Static DRRS involves changing refresh rate (RR) by doing a full modeset
+ * (may appear as a blink on screen) and is used in dock-undock scenario.
+ * Seamless DRRS involves changing RR without any visual effect to the user
+ * and can be used during normal system usage. This is done by programming
+ * certain registers.
+ *
+ * Support for static/seamless DRRS may be indicated in the VBT based on
+ * inputs from the panel spec.
+ *
+ * DRRS saves power by switching to low RR based on usage scenarios.
+ *
+ * eDP DRRS:-
+ * The implementation is based on frontbuffer tracking implementation.
+ * When there is a disturbance on the screen triggered by user activity or a
+ * periodic system activity, DRRS is disabled (RR is changed to high RR).
+ * When there is no movement on screen, after a timeout of 1 second, a switch
+ * to low RR is made.
+ * For integration with frontbuffer tracking code,
+ * intel_edp_drrs_invalidate() and intel_edp_drrs_flush() are called.
+ *
+ * DRRS can be further extended to support other internal panels and also
+ * the scenario of video playback wherein RR is set based on the rate
+ * requested by userspace.
+ */
+
+/**
+ * intel_dp_drrs_init - Init basic DRRS work and mutex.
+ * @intel_connector: eDP connector
+ * @fixed_mode: preferred mode of panel
+ *
+ * This function is called only once at driver load to initialize basic
+ * DRRS stuff.
+ *
+ * Returns:
+ * Downclock mode if panel supports it, else return NULL.
+ * DRRS support is determined by the presence of downclock mode (apart
+ * from VBT setting).
+ */