drm/i915: disable all crtcs at suspend time

We need this to avoid confusing the hw state readout code with the cpt
pch plls at resume time: We'd read the new pipe state (which is
disabled), but still believe that we have a life pll connected to that
pipe (from before the suspend). Hence properly disable pipes to clear
out all the residual state.

This has the neat side-effect that we don't enable ports prematurely
by restoring bogus state from the saved register values.

Reviewed-by: Jesse Barnes <jbarnes@virtuousgeek.org>
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 2a393cb..4c0ec18 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -3545,6 +3545,16 @@
 	}
 }
 
+void intel_modeset_disable(struct drm_device *dev)
+{
+	struct drm_crtc *crtc;
+
+	list_for_each_entry(crtc, &dev->mode_config.crtc_list, head) {
+		if (crtc->enabled)
+			intel_crtc_disable(crtc);
+	}
+}
+
 void intel_encoder_noop(struct drm_encoder *encoder)
 {
 }