drm/i915: Enable FBC at Haswell.

This patch introduce Frame Buffer Compression (FBC) support for HSW.
FBC is tied to primary plane A in HSW.

v2: Ville pointed out docs say FBC must be disabled before disabling
    the plane on HSW.
v3: Really enabling it by default at HSW.

Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@gmail.com>
Tested-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index a14fec3..50814ce 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -3518,11 +3518,12 @@
 	drm_vblank_off(dev, pipe);
 	intel_crtc_update_cursor(crtc, false);
 
-	intel_disable_plane(dev_priv, plane, pipe);
-
+	/* FBC must be disabled before disabling the plane on HSW. */
 	if (dev_priv->cfb_plane == plane)
 		intel_disable_fbc(dev);
 
+	intel_disable_plane(dev_priv, plane, pipe);
+
 	if (intel_crtc->config.has_pch_encoder)
 		intel_set_pch_fifo_underrun_reporting(dev, TRANSCODER_A, false);
 	intel_disable_pipe(dev_priv, pipe);