drm/i915: add encoder->pre_enable/post_disable

The cpu eDP encoder has some horrible hacks to set up the DP pll at
the right time. To be able to move them to the right place, add some
more encoder callbacks so that this can happen at the right time.

LVDS has some similar funky hacks, but that would require more work
(we need to move around the pll setup a bit). Hence for now only
wire these new callbacks up for ilk+ - we only have cpu eDP on these
platforms.

v2: Bikeshed the vtable ordering, requested by Chris Wilson.

Reviewed-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
Signed-Off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/intel_display.c

@@ -3242,6 +3242,10 @@ static void ironlake_crtc_enable(struct drm_crtc *crtc)
 	else
 		ironlake_fdi_disable(crtc);
 
+	for_each_encoder_on_crtc(dev, crtc, encoder)
+		if (encoder->pre_enable)
+			encoder->pre_enable(encoder);
+
 	/* Enable panel fitting for LVDS */
 	if (dev_priv->pch_pf_size &&
 	    (intel_pipe_has_type(crtc, INTEL_OUTPUT_LVDS) || HAS_eDP)) {
@@ -3311,6 +3315,10 @@ static void ironlake_crtc_disable(struct drm_crtc *crtc)
 	I915_WRITE(PF_CTL(pipe), 0);
 	I915_WRITE(PF_WIN_SZ(pipe), 0);
 
+	for_each_encoder_on_crtc(dev, crtc, encoder)
+		if (encoder->post_disable)
+			encoder->post_disable(encoder);
+
 	ironlake_fdi_disable(crtc);
 
 	/* This is a horrible layering violation; we should be doing this in

drivers/gpu/drm/i915/intel_drv.h

@@ -152,8 +152,10 @@ struct intel_encoder {
 	bool cloneable;
 	bool connectors_active;
 	void (*hot_plug)(struct intel_encoder *);
+	void (*pre_enable)(struct intel_encoder *);
 	void (*enable)(struct intel_encoder *);
 	void (*disable)(struct intel_encoder *);
+	void (*post_disable)(struct intel_encoder *);
 	/* Read out the current hw state of this connector, returning true if
 	 * the encoder is active. If the encoder is enabled it also set the pipe
 	 * it is connected to in the pipe parameter. */