diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 9f655e2..1f6fe8c 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -1962,6 +1962,8 @@ struct drm_i915_private {
 	struct i915_suspend_saved_registers regfile;
 	struct vlv_s0ix_state vlv_s0ix_state;
 
+	bool skl_sagv_enabled;
+
 	struct {
 		/*
 		 * Raw watermark latency values:
diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
index 9397dde..89d146f 100644
--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/drivers/gpu/drm/i915/i915_reg.h
@@ -7166,6 +7166,11 @@ enum {
 #define   HSW_PCODE_DE_WRITE_FREQ_REQ		0x17
 #define   DISPLAY_IPS_CONTROL			0x19
 #define	  HSW_PCODE_DYNAMIC_DUTY_CYCLE_CONTROL	0x1A
+#define   GEN9_PCODE_SAGV_CONTROL		0x21
+#define     GEN9_SAGV_DISABLE			0x0
+#define     GEN9_SAGV_LOW_FREQ			0x1
+#define     GEN9_SAGV_HIGH_FREQ			0x2
+#define     GEN9_SAGV_DYNAMIC_FREQ              0x3
 #define GEN6_PCODE_DATA				_MMIO(0x138128)
 #define   GEN6_PCODE_FREQ_IA_RATIO_SHIFT	8
 #define   GEN6_PCODE_FREQ_RING_RATIO_SHIFT	16
diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
index 64d628c..066fe6b 100644
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -2876,6 +2876,109 @@ skl_wm_plane_id(const struct intel_plane *plane)
 }
 
 static void
+skl_sagv_get_hw_state(struct drm_i915_private *dev_priv)
+{
+	u32 temp;
+	int ret;
+
+	if (IS_BROXTON(dev_priv))
+		return;
+
+	mutex_lock(&dev_priv->rps.hw_lock);
+	ret = sandybridge_pcode_read(dev_priv, GEN9_PCODE_SAGV_CONTROL, &temp);
+	mutex_unlock(&dev_priv->rps.hw_lock);
+
+	if (!ret) {
+		dev_priv->skl_sagv_enabled = !!(temp & GEN9_SAGV_DYNAMIC_FREQ);
+	} else {
+		/*
+		 * If for some reason we can't access the SAGV state, follow
+		 * the bspec and assume it's enabled
+		 */
+		DRM_ERROR("Failed to get SAGV state, assuming enabled\n");
+		dev_priv->skl_sagv_enabled = true;
+	}
+}
+
+/*
+ * SAGV dynamically adjusts the system agent voltage and clock frequencies
+ * depending on power and performance requirements. The display engine access
+ * to system memory is blocked during the adjustment time. Having this enabled
+ * in multi-pipe configurations can cause issues (such as underruns causing
+ * full system hangs), and the bspec also suggests that software disable it
+ * when more then one pipe is enabled.
+ */
+static int
+skl_enable_sagv(struct drm_i915_private *dev_priv)
+{
+	int ret;
+
+	if (IS_BROXTON(dev_priv))
+		return 0;
+	if (dev_priv->skl_sagv_enabled)
+		return 0;
+
+	mutex_lock(&dev_priv->rps.hw_lock);
+	DRM_DEBUG_KMS("Enabling the SAGV\n");
+
+	ret = sandybridge_pcode_write(dev_priv, GEN9_PCODE_SAGV_CONTROL,
+				      GEN9_SAGV_DYNAMIC_FREQ);
+	if (!ret)
+		dev_priv->skl_sagv_enabled = true;
+	else
+		DRM_ERROR("Failed to enable the SAGV\n");
+
+	/* We don't need to wait for SAGV when enabling */
+	mutex_unlock(&dev_priv->rps.hw_lock);
+	return ret;
+}
+
+static int
+skl_disable_sagv(struct drm_i915_private *dev_priv)
+{
+	int ret = 0;
+	unsigned long timeout;
+	u32 temp;
+
+	if (IS_BROXTON(dev_priv))
+		return 0;
+	if (!dev_priv->skl_sagv_enabled)
+		return 0;
+
+	mutex_lock(&dev_priv->rps.hw_lock);
+	DRM_DEBUG_KMS("Disabling the SAGV\n");
+
+	/* bspec says to keep retrying for at least 1 ms */
+	timeout = jiffies + msecs_to_jiffies(1);
+	do {
+		ret = sandybridge_pcode_write(dev_priv, GEN9_PCODE_SAGV_CONTROL,
+					      GEN9_SAGV_DISABLE);
+		if (ret) {
+			DRM_ERROR("Failed to disable the SAGV\n");
+			goto out;
+		}
+
+		ret = sandybridge_pcode_read(dev_priv, GEN9_PCODE_SAGV_CONTROL,
+					     &temp);
+		if (ret) {
+			DRM_ERROR("Failed to check the status of the SAGV\n");
+			goto out;
+		}
+	} while (!(temp & 0x1) && time_before(jiffies, timeout));
+
+	if (temp & 0x1) {
+		dev_priv->skl_sagv_enabled = false;
+	} else {
+		ret = -1;
+		DRM_ERROR("Request to disable SAGV timed out\n");
+	}
+
+out:
+	mutex_unlock(&dev_priv->rps.hw_lock);
+	return ret;
+}
+
+static void
 skl_ddb_get_pipe_allocation_limits(struct drm_device *dev,
 				   const struct intel_crtc_state *cstate,
 				   struct skl_ddb_entry *alloc, /* out */
@@ -3686,6 +3789,11 @@ static void skl_write_wm_values(struct drm_i915_private *dev_priv,
 	struct drm_device *dev = &dev_priv->drm;
 	struct intel_crtc *crtc;
 
+	if (dev_priv->active_crtcs == 1)
+		skl_enable_sagv(dev_priv);
+	else
+		skl_disable_sagv(dev_priv);
+
 	for_each_intel_crtc(dev, crtc) {
 		int i, level, max_level = ilk_wm_max_level(dev);
 		enum pipe pipe = crtc->pipe;
@@ -4228,6 +4336,8 @@ void skl_wm_get_hw_state(struct drm_device *dev)
 		/* Easy/common case; just sanitize DDB now if everything off */
 		memset(ddb, 0, sizeof(*ddb));
 	}
+
+	skl_sagv_get_hw_state(dev_priv);
 }
 
 static void ilk_pipe_wm_get_hw_state(struct drm_crtc *crtc)
