drm/i915: Disable/enable planes as the first/last thing during modeset on HSW

Refactor the plane enabling/disabling into helper functions and move
the calls to happen as the first thing during .crtc_disable, and the
last thing during .crtc_enable.

Those are the two clear points where we are sure that the pipe is
actually running regardless of the encoder type or hardware
generation.

v2: Made by Paulo:
  Remove the code touching everything but the Haswell functions. We
  need this change on Haswell right now since it fixes a FIFO underrun
  that we get on pipe A while we enable pipe B (see the workaround
  notes on the Haswell mode set sequence documentation). We can bring
  back the code to gens 2-7 later, once they're tested.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/intel_display.c

@@ -3453,6 +3453,47 @@ static bool hsw_crtc_supports_ips(struct intel_crtc *crtc)
 	return HAS_IPS(crtc->base.dev) && crtc->pipe == PIPE_A;
 }
 
+static void haswell_crtc_enable_planes(struct drm_crtc *crtc)
+{
+	struct drm_device *dev = crtc->dev;
+	struct drm_i915_private *dev_priv = dev->dev_private;
+	struct intel_crtc *intel_crtc = to_intel_crtc(crtc);
+	int pipe = intel_crtc->pipe;
+	int plane = intel_crtc->plane;
+
+	intel_enable_plane(dev_priv, plane, pipe);
+	intel_enable_planes(crtc);
+	intel_crtc_update_cursor(crtc, true);
+
+	hsw_enable_ips(intel_crtc);
+
+	mutex_lock(&dev->struct_mutex);
+	intel_update_fbc(dev);
+	mutex_unlock(&dev->struct_mutex);
+}
+
+static void haswell_crtc_disable_planes(struct drm_crtc *crtc)
+{
+	struct drm_device *dev = crtc->dev;
+	struct drm_i915_private *dev_priv = dev->dev_private;
+	struct intel_crtc *intel_crtc = to_intel_crtc(crtc);
+	int pipe = intel_crtc->pipe;
+	int plane = intel_crtc->plane;
+
+	intel_crtc_wait_for_pending_flips(crtc);
+	drm_vblank_off(dev, pipe);
+
+	/* FBC must be disabled before disabling the plane on HSW. */
+	if (dev_priv->fbc.plane == plane)
+		intel_disable_fbc(dev);
+
+	hsw_disable_ips(intel_crtc);
+
+	intel_crtc_update_cursor(crtc, false);
+	intel_disable_planes(crtc);
+	intel_disable_plane(dev_priv, plane, pipe);
+}
+
 static void haswell_crtc_enable(struct drm_crtc *crtc)
 {
 	struct drm_device *dev = crtc->dev;
@@ -3460,7 +3501,6 @@ static void haswell_crtc_enable(struct drm_crtc *crtc)
 	struct intel_crtc *intel_crtc = to_intel_crtc(crtc);
 	struct intel_encoder *encoder;
 	int pipe = intel_crtc->pipe;
-	int plane = intel_crtc->plane;
 
 	WARN_ON(!crtc->enabled);
 
@@ -3496,24 +3536,17 @@ static void haswell_crtc_enable(struct drm_crtc *crtc)
 	intel_update_watermarks(crtc);
 	intel_enable_pipe(dev_priv, pipe,
 			  intel_crtc->config.has_pch_encoder, false);
-	intel_enable_plane(dev_priv, plane, pipe);
-	intel_enable_planes(crtc);
-	intel_crtc_update_cursor(crtc, true);
-
-	hsw_enable_ips(intel_crtc);
 
 	if (intel_crtc->config.has_pch_encoder)
 		lpt_pch_enable(crtc);
 
-	mutex_lock(&dev->struct_mutex);
-	intel_update_fbc(dev);
-	mutex_unlock(&dev->struct_mutex);
-
 	for_each_encoder_on_crtc(dev, crtc, encoder) {
 		encoder->enable(encoder);
 		intel_opregion_notify_encoder(encoder, true);
 	}
 
+	haswell_crtc_enable_planes(crtc);
+
 	/*
 	 * There seems to be a race in PCH platform hw (at least on some
 	 * outputs) where an enabled pipe still completes any pageflip right
@@ -3620,30 +3653,18 @@ static void haswell_crtc_disable(struct drm_crtc *crtc)
 	struct intel_crtc *intel_crtc = to_intel_crtc(crtc);
 	struct intel_encoder *encoder;
 	int pipe = intel_crtc->pipe;
-	int plane = intel_crtc->plane;
 	enum transcoder cpu_transcoder = intel_crtc->config.cpu_transcoder;
 
 	if (!intel_crtc->active)
 		return;
 
+	haswell_crtc_disable_planes(crtc);
+
 	for_each_encoder_on_crtc(dev, crtc, encoder) {
 		intel_opregion_notify_encoder(encoder, false);
 		encoder->disable(encoder);
 	}
 
-	intel_crtc_wait_for_pending_flips(crtc);
-	drm_vblank_off(dev, pipe);
-
-	/* FBC must be disabled before disabling the plane on HSW. */
-	if (dev_priv->fbc.plane == plane)
-		intel_disable_fbc(dev);
-
-	hsw_disable_ips(intel_crtc);
-
-	intel_crtc_update_cursor(crtc, false);
-	intel_disable_planes(crtc);
-	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);