[alsa-devel] [PATCH v3 3/4] ALSA: hda - display audio call ncts callback

[libin.yang at intel.com]

From: Libin Yang <libin.yang at intel.com>

On some Intel platforms, display audio need set N/CTS
manually at some TMDS frequencies.

Signed-off-by: Libin Yang <libin.yang at intel.com>
---
 sound/pci/hda/patch_hdmi.c | 23 +++++++++++++++++++++++
 1 file changed, 23 insertions(+)

diff --git a/sound/pci/hda/patch_hdmi.c b/sound/pci/hda/patch_hdmi.c
index a97db5f..918435e 100644
--- a/sound/pci/hda/patch_hdmi.c
+++ b/sound/pci/hda/patch_hdmi.c
@@ -1770,6 +1770,16 @@ static bool check_non_pcm_per_cvt(struct hda_codec *codec, hda_nid_t cvt_nid)
 	return non_pcm;
 }
 
+/* There is a fixed mapping between audio pin node and display port
+ * on current Intel platforms:
+ * Pin Widget 5 - PORT B (port = 1 in i915 driver)
+ * Pin Widget 6 - PORT C (port = 2 in i915 driver)
+ * Pin Widget 7 - PORT D (port = 3 in i915 driver)
+ */
+static int intel_pin2port(hda_nid_t pin_nid)
+{
+	return pin_nid - 4;
+}
 
 /*
  * HDMI callbacks
@@ -1786,6 +1796,8 @@ static int generic_hdmi_playback_pcm_prepare(struct hda_pcm_stream *hinfo,
 	int pin_idx = hinfo_to_pin_index(codec, hinfo);
 	struct hdmi_spec_per_pin *per_pin = get_pin(spec, pin_idx);
 	hda_nid_t pin_nid = per_pin->pin_nid;
+	struct snd_pcm_runtime *runtime = substream->runtime;
+	struct i915_audio_component *acomp = codec->bus->core.audio_component;
 	bool non_pcm;
 	int pinctl;
 
@@ -1802,6 +1814,17 @@ static int generic_hdmi_playback_pcm_prepare(struct hda_pcm_stream *hinfo,
 		intel_not_share_assigned_cvt(codec, pin_nid, per_pin->mux_idx);
 	}
 
+	/* Set N/CTS for HSW, BDW and SKL platforms.
+	 * These platforms need call set_ncts to set the N/CTS manually,
+	 * otherwise there is no sound in some sample rates.
+	 */
+	if (is_haswell_plus(codec)) {
+		/* Todo: add DP1.2 MST audio support later */
+		if (acomp && acomp->ops && acomp->ops->set_ncts)
+			acomp->ops->set_ncts(acomp->dev,
+				intel_pin2port(pin_nid),
+				0, runtime->rate);
+	}
 	non_pcm = check_non_pcm_per_cvt(codec, cvt_nid);
 	mutex_lock(&per_pin->lock);
 	per_pin->channels = substream->runtime->channels;
-- 
1.9.1