drm/i915/dp: Remove ->mode_set callback

With all the preceding refactoring the dp mode_set callback only
computes a bit of state (all derived from the pipe config) and also
writes the eld. As long as we do that before we enable the audio bit
or depend upon the correct value in intel_dp->DP we'll be fine.

No other hw state is touched.

We therefore only need to check that clearing intel_dp->DP is save.
Which it is since when we re-enable we already mask out all the bits
the link training code sets. And we need to keep on doing that so that
the re-train loop walking over pre-emph/voltage-swing values still
works properly.
Reviewed-by: Naresh Kumar Kachhi <naresh.kumar.kachhi@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/intel_dp.c

@@ -925,7 +925,7 @@ static void ironlake_set_pll_cpu_edp(struct intel_dp *intel_dp)
 	udelay(500);
 }
 
-static void intel_dp_mode_set(struct intel_encoder *encoder)
+static void intel_dp_prepare(struct intel_encoder *encoder)
 {
 	struct drm_device *dev = encoder->base.dev;
 	struct drm_i915_private *dev_priv = dev->dev_private;
@@ -1902,6 +1902,8 @@ static void g4x_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);
 
+	intel_dp_prepare(encoder);
+
 	/* Only ilk+ has port A */
 	if (dport->port == PORT_A) {
 		ironlake_set_pll_cpu_edp(intel_dp);
@@ -1958,6 +1960,8 @@ static void vlv_dp_pre_pll_enable(struct intel_encoder *encoder)
 	enum dpio_channel port = vlv_dport_to_channel(dport);
 	int pipe = intel_crtc->pipe;
 
+	intel_dp_prepare(encoder);
+
 	/* Program Tx lane resets to default */
 	mutex_lock(&dev_priv->dpio_lock);
 	vlv_dpio_write(dev_priv, pipe, VLV_PCS_DW0(port),
@@ -4224,7 +4228,6 @@ intel_dp_init(struct drm_device *dev, int output_reg, enum port port)
 			 DRM_MODE_ENCODER_TMDS);
 
 	intel_encoder->compute_config = intel_dp_compute_config;
-	intel_encoder->mode_set = intel_dp_mode_set;
 	intel_encoder->disable = intel_disable_dp;
 	intel_encoder->get_hw_state = intel_dp_get_hw_state;
 	intel_encoder->get_config = intel_dp_get_config;