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>

drivers/gpu/drm/i915/i915_reg.h

@@ -2061,6 +2061,16 @@ enum skl_disp_power_wells {
 #define I915_HDMI_LPE_AUDIO_BASE	(VLV_DISPLAY_BASE + 0x65000)
 #define I915_HDMI_LPE_AUDIO_SIZE	0x1000
 
+/* DisplayPort Audio w/ LPE */
+#define _VLV_AUD_PORT_EN_B_DBG		(VLV_DISPLAY_BASE + 0x62F20)
+#define _VLV_AUD_PORT_EN_C_DBG		(VLV_DISPLAY_BASE + 0x62F30)
+#define _VLV_AUD_PORT_EN_D_DBG		(VLV_DISPLAY_BASE + 0x62F34)
+#define VLV_AUD_PORT_EN_DBG(port)	_MMIO_PORT3((port) - PORT_B,	   \
+						    _VLV_AUD_PORT_EN_B_DBG, \
+						    _VLV_AUD_PORT_EN_C_DBG, \
+						    _VLV_AUD_PORT_EN_D_DBG)
+#define VLV_AMP_MUTE		        (1 << 1)
+
 #define GEN6_BSD_RNCID			_MMIO(0x12198)
 
 #define GEN7_FF_THREAD_MODE		_MMIO(0x20a0)

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)