drm/i915: Use intel_dp->DP in eDP PLL setup

Use intel_dp->DP in the eDP PLL setup, instead of doing RMWs.

To do this we need to move DP_AUDIO_OUTPUT_ENABLE setup to happen later,
so that we don't enable audio accidentally while configuring the PLL.

Note that actually we already enabled audio before the port due to
the double port register write magic required by VLV/CHV from
7b713f50 ("drm/i915: Fix eDP link training when switching pipes on VLV/CHV")
So that gets changed now to keep audio off as long as the port is off.

Also intel_dp_link_down() must be made to update intel_dp->DP so that we
don't re-enable the port by accident when turning off the PLL. This is
safe now that we don't call intel_dp_link_down() during link retraining.

v2: Add a note about the audio vs. port enable (Daniel)
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1447164977-32315-1-git-send-email-ville.syrjala@linux.intel.comReviewed-by: Jani Nikula <jani.nikula@intel.com>

drivers/gpu/drm/i915/intel_dp.c

@@ -1551,23 +1551,18 @@ static void ironlake_set_pll_cpu_edp(struct intel_dp *intel_dp)
 	struct intel_crtc *crtc = to_intel_crtc(dig_port->base.base.crtc);
 	struct drm_device *dev = crtc->base.dev;
 	struct drm_i915_private *dev_priv = dev->dev_private;
-	u32 dpa_ctl;
 
 	DRM_DEBUG_KMS("eDP PLL enable for clock %d\n",
 		      crtc->config->port_clock);
-	dpa_ctl = I915_READ(DP_A);
-	dpa_ctl &= ~DP_PLL_FREQ_MASK;
 
-	if (crtc->config->port_clock == 162000) {
-		dpa_ctl |= DP_PLL_FREQ_162MHZ;
+	intel_dp->DP &= ~DP_PLL_FREQ_MASK;
+
+	if (crtc->config->port_clock == 162000)
 		intel_dp->DP |= DP_PLL_FREQ_162MHZ;
-	} else {
-		dpa_ctl |= DP_PLL_FREQ_270MHZ;
+	else
 		intel_dp->DP |= DP_PLL_FREQ_270MHZ;
-	}
-
-	I915_WRITE(DP_A, dpa_ctl);
 
+	I915_WRITE(DP_A, intel_dp->DP);
 	POSTING_READ(DP_A);
 	udelay(500);
 }
@@ -1616,9 +1611,6 @@ static void intel_dp_prepare(struct intel_encoder *encoder)
 	intel_dp->DP |= DP_VOLTAGE_0_4 | DP_PRE_EMPHASIS_0;
 	intel_dp->DP |= DP_PORT_WIDTH(crtc->config->lane_count);
 
-	if (crtc->config->has_audio)
-		intel_dp->DP |= DP_AUDIO_OUTPUT_ENABLE;
-
 	/* Split out the IBX/CPU vs CPT settings */
 
 	if (IS_GEN7(dev) && port == PORT_A) {
@@ -2179,20 +2171,14 @@ static void ironlake_edp_pll_on(struct intel_dp *intel_dp)
 	struct intel_digital_port *intel_dig_port = dp_to_dig_port(intel_dp);
 	struct intel_crtc *crtc = to_intel_crtc(intel_dig_port->base.base.crtc);
 	struct drm_i915_private *dev_priv = to_i915(crtc->base.dev);
-	u32 dpa_ctl;
 
 	assert_pipe_disabled(dev_priv, crtc->pipe);
 	assert_dp_port_disabled(intel_dp);
 	assert_edp_pll_disabled(dev_priv);
 
 	DRM_DEBUG_KMS("\n");
-	dpa_ctl = I915_READ(DP_A);
-
-	/* We don't adjust intel_dp->DP while tearing down the link, to
-	 * facilitate link retraining (e.g. after hotplug). Hence clear all
-	 * enable bits here to ensure that we don't enable too much. */
-	intel_dp->DP &= ~(DP_PORT_EN | DP_AUDIO_OUTPUT_ENABLE);
 	intel_dp->DP |= DP_PLL_ENABLE;
+
 	I915_WRITE(DP_A, intel_dp->DP);
 	POSTING_READ(DP_A);
 	udelay(200);
@@ -2203,19 +2189,14 @@ static void ironlake_edp_pll_off(struct intel_dp *intel_dp)
 	struct intel_digital_port *intel_dig_port = dp_to_dig_port(intel_dp);
 	struct intel_crtc *crtc = to_intel_crtc(intel_dig_port->base.base.crtc);
 	struct drm_i915_private *dev_priv = to_i915(crtc->base.dev);
-	u32 dpa_ctl;
 
 	assert_pipe_disabled(dev_priv, crtc->pipe);
 	assert_dp_port_disabled(intel_dp);
 	assert_edp_pll_enabled(dev_priv);
 
-	dpa_ctl = I915_READ(DP_A);
+	intel_dp->DP &= ~DP_PLL_ENABLE;
 
-	/* We can't rely on the value tracked for the DP register in
-	 * intel_dp->DP because link_down must not change that (otherwise link
-	 * re-training will fail. */
-	dpa_ctl &= ~DP_PLL_ENABLE;
-	I915_WRITE(DP_A, dpa_ctl);
+	I915_WRITE(DP_A, intel_dp->DP);
 	POSTING_READ(DP_A);
 	udelay(200);
 }
@@ -2571,6 +2552,8 @@ static void intel_dp_enable_port(struct intel_dp *intel_dp)
 {
 	struct drm_device *dev = intel_dp_to_dev(intel_dp);
 	struct drm_i915_private *dev_priv = dev->dev_private;
+	struct intel_crtc *crtc =
+		to_intel_crtc(dp_to_dig_port(intel_dp)->base.base.crtc);
 
 	/* enable with pattern 1 (as per spec) */
 	_intel_dp_set_link_train(intel_dp, &intel_dp->DP,
@@ -2586,6 +2569,8 @@ static void intel_dp_enable_port(struct intel_dp *intel_dp)
 	 * fail when the power sequencer is freshly used for this port.
 	 */
 	intel_dp->DP |= DP_PORT_EN;
+	if (crtc->config->has_audio)
+		intel_dp->DP |= DP_AUDIO_OUTPUT_ENABLE;
 
 	I915_WRITE(intel_dp->output_reg, intel_dp->DP);
 	POSTING_READ(intel_dp->output_reg);
@@ -3726,6 +3711,8 @@ intel_dp_link_down(struct intel_dp *intel_dp)
 	}
 
 	msleep(intel_dp->panel_power_down_delay);
+
+	intel_dp->DP = DP;
 }
 
 static bool