1 files changed, 30 insertions, 1 deletions

diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
index ccbdd83f5220..d10e6735771f 100644
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -5500,9 +5500,38 @@ void intel_gt_init(struct drm_device *dev)
         if (IS_VALLEYVIEW(dev)) {
                 dev_priv->gt.force_wake_get = vlv_force_wake_get;
                 dev_priv->gt.force_wake_put = vlv_force_wake_put;
-        } else if (IS_IVYBRIDGE(dev) || IS_HASWELL(dev)) {
+        } else if (IS_HASWELL(dev)) {
                 dev_priv->gt.force_wake_get = __gen6_gt_force_wake_mt_get;
                 dev_priv->gt.force_wake_put = __gen6_gt_force_wake_mt_put;
+        } else if (IS_IVYBRIDGE(dev)) {
+                u32 ecobus;
+
+                /* IVB configs may use multi-threaded forcewake */
+
+                /* A small trick here - if the bios hasn't configured
+                 * MT forcewake, and if the device is in RC6, then
+                 * force_wake_mt_get will not wake the device and the
+                 * ECOBUS read will return zero. Which will be
+                 * (correctly) interpreted by the test below as MT
+                 * forcewake being disabled.
+                 */
+                mutex_lock(&dev->struct_mutex);
+                __gen6_gt_force_wake_mt_get(dev_priv);
+                ecobus = I915_READ_NOTRACE(ECOBUS);
+                __gen6_gt_force_wake_mt_put(dev_priv);
+                mutex_unlock(&dev->struct_mutex);
+
+                if (ecobus & FORCEWAKE_MT_ENABLE) {
+                        dev_priv->gt.force_wake_get =
+                                                __gen6_gt_force_wake_mt_get;
+                        dev_priv->gt.force_wake_put =
+                                                __gen6_gt_force_wake_mt_put;
+                } else {
+                        DRM_INFO("No MT forcewake available on Ivybridge, this can result in issues\n");
+                        DRM_INFO("when using vblank-synced partial screen updates.\n");
+                        dev_priv->gt.force_wake_get = __gen6_gt_force_wake_get;
+                        dev_priv->gt.force_wake_put = __gen6_gt_force_wake_put;
+                }
         } else if (IS_GEN6(dev)) {
                 dev_priv->gt.force_wake_get = __gen6_gt_force_wake_get;
                 dev_priv->gt.force_wake_put = __gen6_gt_force_wake_put;