drm/i915: Restore vblank interrupts earlier

Plane sanitation needs vblank interrupts (on account of CxSR disable).
So let's restore vblank interrupts earlier.

v2: Make it actually build
v3: Add comment to explain why we need this (Daniel)

Cc: stable@vger.kernel.org
Cc: Dennis <dennis.nezic@utoronto.ca>
Tested-by: Dennis <dennis.nezic@utoronto.ca>
Tested-by: Peter Nowee <peter.nowee@gmail.com>
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=105637
Fixes: b1e01595 ("drm/i915: Redo plane sanitation during readout")
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20181003144951.4397-1-ville.syrjala@linux.intel.com

drivers/gpu/drm/i915/intel_display.c

@@ -15570,13 +15570,9 @@ static void intel_sanitize_crtc(struct intel_crtc *crtc,
 			   I915_READ(reg) & ~PIPECONF_FRAME_START_DELAY_MASK);
 	}
 
-	/* restore vblank interrupts to correct state */
-	drm_crtc_vblank_reset(&crtc->base);
 	if (crtc->active) {
 		struct intel_plane *plane;
 
-		drm_crtc_vblank_on(&crtc->base);
-
 		/* Disable everything but the primary plane */
 		for_each_intel_plane_on_crtc(dev, crtc, plane) {
 			const struct intel_plane_state *plane_state =
@@ -15918,7 +15914,6 @@ intel_modeset_setup_hw_state(struct drm_device *dev,
 			     struct drm_modeset_acquire_ctx *ctx)
 {
 	struct drm_i915_private *dev_priv = to_i915(dev);
-	enum pipe pipe;
 	struct intel_crtc *crtc;
 	struct intel_encoder *encoder;
 	int i;
@@ -15931,15 +15926,23 @@ intel_modeset_setup_hw_state(struct drm_device *dev,
 	/* HW state is read out, now we need to sanitize this mess. */
 	get_encoder_power_domains(dev_priv);
 
-	intel_sanitize_plane_mapping(dev_priv);
+	/*
+	 * intel_sanitize_plane_mapping() may need to do vblank
+	 * waits, so we need vblank interrupts restored beforehand.
+	 */
+	for_each_intel_crtc(&dev_priv->drm, crtc) {
+		drm_crtc_vblank_reset(&crtc->base);
 
-	for_each_intel_encoder(dev, encoder) {
-		intel_sanitize_encoder(encoder);
+		if (crtc->active)
+			drm_crtc_vblank_on(&crtc->base);
 	}
 
-	for_each_pipe(dev_priv, pipe) {
-		crtc = intel_get_crtc_for_pipe(dev_priv, pipe);
+	intel_sanitize_plane_mapping(dev_priv);
 
+	for_each_intel_encoder(dev, encoder)
+		intel_sanitize_encoder(encoder);
+
+	for_each_intel_crtc(&dev_priv->drm, crtc) {
 		intel_sanitize_crtc(crtc, ctx);
 		intel_dump_pipe_config(crtc, crtc->config,
 				       "[setup_hw_state]");