ALSA: hda/hdmi: expose ELD control

Applications may want to read ELD information to
understand what codecs are supported on the HDMI
receiver and handle the a-v delay for better lip-sync.

ELD information is exposed in a device-specific
IFACE_PCM kcontrol. Tested both with amixer and
PulseAudio; with a corresponding patch passthrough modes
are enabled automagically.

ELD control size is set to zero in case of errors or
wrong configurations. No notifications are implemented
for now, it is expected that jack detection is used to
reconfigure the audio outputs.

Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

1 files changed, 68 insertions, 0 deletions

diff --git a/sound/pci/hda/patch_hdmi.c b/sound/pci/hda/patch_hdmi.c
index 3f1f6ac8e64..342540128fb 100644
--- a/sound/pci/hda/patch_hdmi.c
+++ b/sound/pci/hda/patch_hdmi.c
@@ -324,6 +324,66 @@ static int cvt_nid_to_cvt_index(struct hdmi_spec *spec, hda_nid_t cvt_nid)
 	return -EINVAL;
 }
 
+static int hdmi_eld_ctl_info(struct snd_kcontrol *kcontrol,
+			struct snd_ctl_elem_info *uinfo)
+{
+	struct hda_codec *codec = snd_kcontrol_chip(kcontrol);
+	struct hdmi_spec *spec;
+	int pin_idx;
+
+	spec = codec->spec;
+	uinfo->type = SNDRV_CTL_ELEM_TYPE_BYTES;
+
+	pin_idx = kcontrol->private_value;
+	uinfo->count = spec->pins[pin_idx].sink_eld.eld_size;
+
+	return 0;
+}
+
+static int hdmi_eld_ctl_get(struct snd_kcontrol *kcontrol,
+			struct snd_ctl_elem_value *ucontrol)
+{
+	struct hda_codec *codec = snd_kcontrol_chip(kcontrol);
+	struct hdmi_spec *spec;
+	int pin_idx;
+
+	spec = codec->spec;
+	pin_idx = kcontrol->private_value;
+
+	memcpy(ucontrol->value.bytes.data,
+		spec->pins[pin_idx].sink_eld.eld_buffer, ELD_MAX_SIZE);
+
+	return 0;
+}
+
+static struct snd_kcontrol_new eld_bytes_ctl = {
+	.access = SNDRV_CTL_ELEM_ACCESS_READ | SNDRV_CTL_ELEM_ACCESS_VOLATILE,
+	.iface = SNDRV_CTL_ELEM_IFACE_PCM,
+	.name = "ELD",
+	.info = hdmi_eld_ctl_info,
+	.get = hdmi_eld_ctl_get,
+};
+
+static int hdmi_create_eld_ctl(struct hda_codec *codec, int pin_idx,
+			int device)
+{
+	struct snd_kcontrol *kctl;
+	struct hdmi_spec *spec = codec->spec;
+	int err;
+
+	kctl = snd_ctl_new1(&eld_bytes_ctl, codec);
+	if (!kctl)
+		return -ENOMEM;
+	kctl->private_value = pin_idx;
+	kctl->id.device = device;
+
+	err = snd_hda_ctl_add(codec, spec->pins[pin_idx].pin_nid, kctl);
+	if (err < 0)
+		return err;
+
+	return 0;
+}
+
 #ifdef BE_PARANOID
 static void hdmi_get_dip_index(struct hda_codec *codec, hda_nid_t pin_nid,
 				int *packet_index, int *byte_index)
@@ -1193,6 +1253,14 @@ static int generic_hdmi_build_controls(struct hda_codec *codec)
 		if (err < 0)
 			return err;
 		snd_hda_spdif_ctls_unassign(codec, pin_idx);
+
+		/* add control for ELD Bytes */
+		err = hdmi_create_eld_ctl(codec,
+					pin_idx,
+					spec->pcm_rec[pin_idx].device);
+
+		if (err < 0)
+			return err;
 	}
 
 	return 0;