2 files changed, 3 insertions, 0 deletions

diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
index 4a446b116e6a..96fb0fa47c40 100644
--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/drivers/gpu/drm/i915/i915_reg.h
@@ -579,6 +579,7 @@
 #define   DPFC_CTL_PLANEA       (0<<30)
 #define   DPFC_CTL_PLANEB       (1<<30)
 #define   DPFC_CTL_FENCE_EN     (1<<29)
+#define   DPFC_CTL_PERSISTENT_MODE      (1<<25)
 #define   DPFC_SR_EN            (1<<10)
 #define   DPFC_CTL_LIMIT_1X     (0<<6)
 #define   DPFC_CTL_LIMIT_2X     (1<<6)
diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 31c75266a456..9df96bdc002e 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -1581,6 +1581,8 @@ static void ironlake_enable_fbc(struct drm_crtc *crtc, unsigned long interval)
 
         dpfc_ctl &= DPFC_RESERVED;
         dpfc_ctl |= (plane | DPFC_CTL_LIMIT_1X);
+        /* Set persistent mode for front-buffer rendering, ala X. */
+        dpfc_ctl |= DPFC_CTL_PERSISTENT_MODE;
         dpfc_ctl |= (DPFC_CTL_FENCE_EN | dev_priv->cfb_fence);
         I915_WRITE(ILK_DPFC_CHICKEN, DPFC_HT_MODIFY);