drm/i915: add DisplayPort amp unmute for LPE audio mode

Enable unmute/mute amp notification. This doesn't seem to affect
HDMI support so this is done unconditionally.

An earlier version of this patch set a chicken bit at address 0x62F38
prior to the mute/unmute but this register doesn't seem to do anything
so this phase was removed.

v1->v2: Drop needless pipe A check, avoid temporary reg offset variable.
v2->v3: Add "_" prefix to VLV_AUD_PORT_EN_X_DBG as they are internal.

Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Acked-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
diff --git a/drivers/gpu/drm/i915/intel_lpe_audio.c b/drivers/gpu/drm/i915/intel_lpe_audio.c
index 245523e..5da14f4 100644
--- a/drivers/gpu/drm/i915/intel_lpe_audio.c
+++ b/drivers/gpu/drm/i915/intel_lpe_audio.c
@@ -337,6 +337,7 @@ void intel_lpe_audio_notify(struct drm_i915_private *dev_priv,
 {
 	unsigned long irq_flags;
 	struct intel_hdmi_lpe_audio_pdata *pdata = NULL;
+	u32 audio_enable;
 
 	if (!HAS_LPE_AUDIO(dev_priv))
 		return;
@@ -346,6 +347,8 @@ void intel_lpe_audio_notify(struct drm_i915_private *dev_priv,
 
 	spin_lock_irqsave(&pdata->lpe_audio_slock, irq_flags);
 
+	audio_enable = I915_READ(VLV_AUD_PORT_EN_DBG(port));
+
 	if (eld != NULL) {
 		memcpy(pdata->eld.eld_data, eld,
 			HDMI_MAX_ELD_BYTES);
@@ -357,11 +360,20 @@ void intel_lpe_audio_notify(struct drm_i915_private *dev_priv,
 			pdata->tmds_clock_speed = tmds_clk_speed;
 		if (link_rate)
 			pdata->link_rate = link_rate;
+
+		/* Unmute the amp for both DP and HDMI */
+		I915_WRITE(VLV_AUD_PORT_EN_DBG(port),
+			   audio_enable & ~VLV_AMP_MUTE);
+
 	} else {
 		memset(pdata->eld.eld_data, 0,
 			HDMI_MAX_ELD_BYTES);
 		pdata->hdmi_connected = false;
 		pdata->dp_output = false;
+
+		/* Mute the amp for both DP and HDMI */
+		I915_WRITE(VLV_AUD_PORT_EN_DBG(port),
+			   audio_enable | VLV_AMP_MUTE);
 	}
 
 	if (pdata->notify_audio_lpe)