drm/i915: Improve assert_planes_disabled()

Ever since gen4 primary planes were fixed to pipes.

And for gen2-3, don't check plane B if it doesn't exist.
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@gmail.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/intel_display.c

@@ -1105,12 +1105,13 @@ static void assert_plane(struct drm_i915_private *dev_priv,
 static void assert_planes_disabled(struct drm_i915_private *dev_priv,
 				   enum pipe pipe)
 {
+	struct drm_device *dev = dev_priv->dev;
 	int reg, i;
 	u32 val;
 	int cur_pipe;
 
-	/* Planes are fixed to pipes on ILK+ */
-	if (HAS_PCH_SPLIT(dev_priv->dev) || IS_VALLEYVIEW(dev_priv->dev)) {
+	/* Primary planes are fixed to pipes on gen4+ */
+	if (INTEL_INFO(dev)->gen >= 4) {
 		reg = DSPCNTR(pipe);
 		val = I915_READ(reg);
 		WARN((val & DISPLAY_PLANE_ENABLE),
@@ -1120,7 +1121,7 @@ static void assert_planes_disabled(struct drm_i915_private *dev_priv,
 	}
 
 	/* Need to check both planes against the pipe */
-	for (i = 0; i < 2; i++) {
+	for (i = 0; i < INTEL_INFO(dev)->num_pipes; i++) {
 		reg = DSPCNTR(i);
 		val = I915_READ(reg);
 		cur_pipe = (val & DISPPLANE_SEL_PIPE_MASK) >>