drm/i915: introduce intel_has_sagv()

And use it to move knowledge about the SAGV-supporting platforms from
the callers to the SAGV code.

We'll add more platforms to intel_has_sagv(), so IMHO it makes more
sense to move all this to a single function instead of patching all
the callers every time we add SAGV support to a new platform.

v2: Move I915_SAGV_NOT_CONTROLLED to the new function (Lyude).

Cc: stable@vger.kernel.org
Reviewed-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Signed-off-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1474578035-424-3-git-send-email-paulo.r.zanoni@intel.com
(cherry picked from commit 56feca91)
Signed-off-by: Jani Nikula <jani.nikula@intel.com>

drivers/gpu/drm/i915/intel_display.c

@@ -14367,7 +14367,7 @@ static void intel_atomic_commit_tail(struct drm_atomic_state *state)
 		 * SKL workaround: bspec recommends we disable the SAGV when we
 		 * have more then one pipe enabled
 		 */
-		if (IS_SKYLAKE(dev_priv) && !intel_can_enable_sagv(state))
+		if (!intel_can_enable_sagv(state))
 			intel_disable_sagv(dev_priv);
 
 		intel_modeset_verify_disabled(dev);
@@ -14425,8 +14425,7 @@ static void intel_atomic_commit_tail(struct drm_atomic_state *state)
 		intel_modeset_verify_crtc(crtc, old_crtc_state, crtc->state);
 	}
 
-	if (IS_SKYLAKE(dev_priv) && intel_state->modeset &&
-	    intel_can_enable_sagv(state))
+	if (intel_state->modeset && intel_can_enable_sagv(state))
 		intel_enable_sagv(dev_priv);
 
 	drm_atomic_helper_commit_hw_done(state);

drivers/gpu/drm/i915/intel_pm.c

@@ -2877,6 +2877,13 @@ skl_wm_plane_id(const struct intel_plane *plane)
 	}
 }
 
+static bool
+intel_has_sagv(struct drm_i915_private *dev_priv)
+{
+	return IS_SKYLAKE(dev_priv) &&
+	       dev_priv->sagv_status != I915_SAGV_NOT_CONTROLLED;
+}
+
 /*
  * SAGV dynamically adjusts the system agent voltage and clock frequencies
  * depending on power and performance requirements. The display engine access
@@ -2893,8 +2900,10 @@ intel_enable_sagv(struct drm_i915_private *dev_priv)
 {
 	int ret;
 
-	if (dev_priv->sagv_status == I915_SAGV_NOT_CONTROLLED ||
-	    dev_priv->sagv_status == I915_SAGV_ENABLED)
+	if (!intel_has_sagv(dev_priv))
+		return 0;
+
+	if (dev_priv->sagv_status == I915_SAGV_ENABLED)
 		return 0;
 
 	DRM_DEBUG_KMS("Enabling the SAGV\n");
@@ -2942,8 +2951,10 @@ intel_disable_sagv(struct drm_i915_private *dev_priv)
 {
 	int ret, result;
 
-	if (dev_priv->sagv_status == I915_SAGV_NOT_CONTROLLED ||
-	    dev_priv->sagv_status == I915_SAGV_DISABLED)
+	if (!intel_has_sagv(dev_priv))
+		return 0;
+
+	if (dev_priv->sagv_status == I915_SAGV_DISABLED)
 		return 0;
 
 	DRM_DEBUG_KMS("Disabling the SAGV\n");
@@ -2984,6 +2995,9 @@ bool intel_can_enable_sagv(struct drm_atomic_state *state)
 	enum pipe pipe;
 	int level, plane;
 
+	if (!intel_has_sagv(dev_priv))
+		return false;
+
 	/*
 	 * SKL workaround: bspec recommends we disable the SAGV when we have
 	 * more then one pipe enabled