drm/i915: rearrange vlv dp enable and pre_enable callbacks

VLV wants encoder enabling before the pipe is up. This is currently
achieved through calling the ->enable callback early, right after the
->pre_enable callback, in valleyview_crtc_enable(). This loses both the
distinction between ->pre_enable and ->enable on VLV and the possibility
to use a hook at the end of the modeset sequence.

Rearrange the DP callbacks to make it possible to move ->enable call
later. Basically do everything in ->pre_enable on VLV, and make ->enable
a NOP.

There should be no functional changes.

v2: Rebase.

v3: Explain why this is needed in the commit message (Chris).
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/intel_dp.c

@@ -1700,34 +1700,34 @@ static void intel_enable_dp(struct intel_encoder *encoder)
 	intel_dp_complete_link_train(intel_dp);
 	intel_dp_stop_link_train(intel_dp);
 	ironlake_edp_backlight_on(intel_dp);
+}
 
-	if (IS_VALLEYVIEW(dev)) {
-		struct intel_digital_port *dport =
-			enc_to_dig_port(&encoder->base);
-		int channel = vlv_dport_to_channel(dport);
-
-		vlv_wait_port_ready(dev_priv, channel);
-	}
+static void vlv_enable_dp(struct intel_encoder *encoder)
+{
 }
 
 static void intel_pre_enable_dp(struct intel_encoder *encoder)
 {
 	struct intel_dp *intel_dp = enc_to_intel_dp(&encoder->base);
 	struct intel_digital_port *dport = dp_to_dig_port(intel_dp);
-	struct drm_device *dev = encoder->base.dev;
-	struct drm_i915_private *dev_priv = dev->dev_private;
 
-	if (dport->port == PORT_A && !IS_VALLEYVIEW(dev))
+	if (dport->port == PORT_A)
 		ironlake_edp_pll_on(intel_dp);
+}
 
-	if (IS_VALLEYVIEW(dev)) {
-		struct intel_crtc *intel_crtc =
-			to_intel_crtc(encoder->base.crtc);
+static void vlv_pre_enable_dp(struct intel_encoder *encoder)
+{
+	struct intel_dp *intel_dp = enc_to_intel_dp(&encoder->base);
+	struct intel_digital_port *dport = dp_to_dig_port(intel_dp);
+	struct drm_device *dev = encoder->base.dev;
+	struct drm_i915_private *dev_priv = dev->dev_private;
+	struct intel_crtc *intel_crtc = to_intel_crtc(encoder->base.crtc);
 	int port = vlv_dport_to_channel(dport);
 	int pipe = intel_crtc->pipe;
 	u32 val;
 
 	mutex_lock(&dev_priv->dpio_lock);
+
 	val = vlv_dpio_read(dev_priv, DPIO_DATA_LANE_A(port));
 	val = 0;
 	if (pipe)
@@ -1736,13 +1736,14 @@ static void intel_pre_enable_dp(struct intel_encoder *encoder)
 		val &= ~(1<<21);
 	val |= 0x001000c4;
 	vlv_dpio_write(dev_priv, DPIO_DATA_CHANNEL(port), val);
+	vlv_dpio_write(dev_priv, DPIO_PCS_CLOCKBUF0(port), 0x00760018);
+	vlv_dpio_write(dev_priv, DPIO_PCS_CLOCKBUF8(port), 0x00400888);
 
-		vlv_dpio_write(dev_priv, DPIO_PCS_CLOCKBUF0(port),
-				 0x00760018);
-		vlv_dpio_write(dev_priv, DPIO_PCS_CLOCKBUF8(port),
-				 0x00400888);
 	mutex_unlock(&dev_priv->dpio_lock);
-	}
+
+	intel_enable_dp(encoder);
+
+	vlv_wait_port_ready(dev_priv, port);
 }
 
 static void intel_dp_pre_pll_enable(struct intel_encoder *encoder)
@@ -3522,14 +3523,18 @@ intel_dp_init(struct drm_device *dev, int output_reg, enum port port)
 
 	intel_encoder->compute_config = intel_dp_compute_config;
 	intel_encoder->mode_set = intel_dp_mode_set;
-	intel_encoder->enable = intel_enable_dp;
-	intel_encoder->pre_enable = intel_pre_enable_dp;
 	intel_encoder->disable = intel_disable_dp;
 	intel_encoder->post_disable = intel_post_disable_dp;
 	intel_encoder->get_hw_state = intel_dp_get_hw_state;
 	intel_encoder->get_config = intel_dp_get_config;
-	if (IS_VALLEYVIEW(dev))
+	if (IS_VALLEYVIEW(dev)) {
 		intel_encoder->pre_pll_enable = intel_dp_pre_pll_enable;
+		intel_encoder->pre_enable = vlv_pre_enable_dp;
+		intel_encoder->enable = vlv_enable_dp;
+	} else {
+		intel_encoder->pre_enable = intel_pre_enable_dp;
+		intel_encoder->enable = intel_enable_dp;
+	}
 
 	intel_dig_port->port = port;
 	intel_dig_port->dp.output_reg = output_reg;