1 files changed, 16 insertions, 8 deletions

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 3bc6ab56cf8b..841f0397288b 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -1516,8 +1516,10 @@ static void intel_enable_pipe(struct drm_i915_private *dev_priv, enum pipe pipe,
 
         reg = PIPECONF(pipe);
         val = I915_READ(reg);
-        val |= PIPECONF_ENABLE;
-        I915_WRITE(reg, val);
+        if (val & PIPECONF_ENABLE)
+                return;
+
+        I915_WRITE(reg, val | PIPECONF_ENABLE);
         intel_wait_for_vblank(dev_priv->dev, pipe);
 }
 
@@ -1551,8 +1553,10 @@ static void intel_disable_pipe(struct drm_i915_private *dev_priv,
 
         reg = PIPECONF(pipe);
         val = I915_READ(reg);
-        val &= ~PIPECONF_ENABLE;
-        I915_WRITE(reg, val);
+        if ((val & PIPECONF_ENABLE) == 0)
+                return;
+
+        I915_WRITE(reg, val & ~PIPECONF_ENABLE);
         intel_wait_for_pipe_off(dev_priv->dev, pipe);
 }
 
@@ -1575,8 +1579,10 @@ static void intel_enable_plane(struct drm_i915_private *dev_priv,
 
         reg = DSPCNTR(plane);
         val = I915_READ(reg);
-        val |= DISPLAY_PLANE_ENABLE;
-        I915_WRITE(reg, val);
+        if (val & DISPLAY_PLANE_ENABLE)
+                return;
+
+        I915_WRITE(reg, val | DISPLAY_PLANE_ENABLE);
         intel_wait_for_vblank(dev_priv->dev, pipe);
 }
 
@@ -1607,8 +1613,10 @@ static void intel_disable_plane(struct drm_i915_private *dev_priv,
 
         reg = DSPCNTR(plane);
         val = I915_READ(reg);
-        val &= ~DISPLAY_PLANE_ENABLE;
-        I915_WRITE(reg, val);
+        if ((val & DISPLAY_PLANE_ENABLE) == 0)
+                return;
+
+        I915_WRITE(reg, val & ~DISPLAY_PLANE_ENABLE);
         intel_flush_display_plane(dev_priv, plane);
         intel_wait_for_vblank(dev_priv->dev, pipe);
 }