drm/i915: Disable CRT port after pipe on PCH platforms

Follow the BSpec sequence for the CRT port as well on PCH platforms,
ie. disable the pipe before the port.

Didn't bother looking at DDI in detail yet, so leave that one be even
though the CRT is a PCH port there.
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/intel_crt.c

@@ -207,6 +207,14 @@ static void intel_disable_crt(struct intel_encoder *encoder)
 	intel_crt_set_dpms(encoder, DRM_MODE_DPMS_OFF);
 }
 
+static void pch_disable_crt(struct intel_encoder *encoder)
+{
+}
+
+static void pch_post_disable_crt(struct intel_encoder *encoder)
+{
+	intel_disable_crt(encoder);
+}
 
 static void hsw_crt_post_disable(struct intel_encoder *encoder)
 {
@@ -888,7 +896,12 @@ void intel_crt_init(struct drm_device *dev)
 		crt->adpa_reg = ADPA;
 
 	crt->base.compute_config = intel_crt_compute_config;
+	if (HAS_PCH_SPLIT(dev) && !HAS_DDI(dev)) {
+		crt->base.disable = pch_disable_crt;
+		crt->base.post_disable = pch_post_disable_crt;
+	} else {
 		crt->base.disable = intel_disable_crt;
+	}
 	crt->base.enable = intel_enable_crt;
 	if (I915_HAS_HOTPLUG(dev))
 		crt->base.hpd_pin = HPD_CRT;