[alsa-devel] [PATCH v2] ALSA: hda - program ICT bits to support HBR audio

[Pierre-Louis Bossart]

From: Sriram Periyasamy <sriramx.periyasamy at intel.com>

On recent Intel platforms (Haswell, Broadwell, Skylake, ApolloLake,
KabyLake, ...), the IEC Coding Type (ICT) bitfield in the Digital
Converter Control #3 needs to be set explicitly for HDMI/DisplayPort
High Bit Rate (HBR) audio playback to work. This was not required in
earlier platforms when HBR was first introduced. The ICT bits are
defined in Section 7.3.3.9 of the HDaudio 1.0a specification.

Since the ICT bitfield was not specified for HDAudio 1.0 devices
(before 2009), we only program it on machines more recent than
Haswell.

We tested that this fix is not needed on Baytrail-I (MinnowBoard
Turbot) and believe by extension it also does not apply to Braswell.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=98797

Signed-off-by: Sriram Periyasamy <sriramx.periyasamy at intel.com>
Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart at linux.intel.com>
Signed-off-by: Subhransu S. Prusty <subhransu.s.prusty at intel.com>
---
v2: move digi3 verb in Set section, only set ICT for haswell and newer

 include/sound/hda_verbs.h  |  1 +
 sound/pci/hda/patch_hdmi.c | 21 +++++++++++++++++++++
 2 files changed, 22 insertions(+)

diff --git a/include/sound/hda_verbs.h b/include/sound/hda_verbs.h
index d0509db6d0ec..d2004d7feb2b 100644
--- a/include/sound/hda_verbs.h
+++ b/include/sound/hda_verbs.h
@@ -54,6 +54,7 @@ enum {
 #define AC_VERB_GET_EAPD_BTLENABLE		0x0f0c
 #define AC_VERB_GET_DIGI_CONVERT_1		0x0f0d
 #define AC_VERB_GET_DIGI_CONVERT_2		0x0f0e /* unused */
+#define AC_VERB_SET_DIGI_CONVERT_3		0x73e
 #define AC_VERB_GET_VOLUME_KNOB_CONTROL		0x0f0f
 /* f10-f1a: GPIO */
 #define AC_VERB_GET_GPIO_DATA			0x0f15
diff --git a/sound/pci/hda/patch_hdmi.c b/sound/pci/hda/patch_hdmi.c
index 53f9311370de..8566de298ea3 100644
--- a/sound/pci/hda/patch_hdmi.c
+++ b/sound/pci/hda/patch_hdmi.c
@@ -906,6 +906,7 @@ static int hdmi_setup_stream(struct hda_codec *codec, hda_nid_t cvt_nid,
 			      hda_nid_t pin_nid, u32 stream_tag, int format)
 {
 	struct hdmi_spec *spec = codec->spec;
+	unsigned int param;
 	int err;
 
 	err = spec->ops.pin_hbr_setup(codec, pin_nid, is_hbr_format(format));
@@ -915,6 +916,26 @@ static int hdmi_setup_stream(struct hda_codec *codec, hda_nid_t cvt_nid,
 		return err;
 	}
 
+	if (is_haswell_plus(codec)) {
+
+		/*
+		 * on recent platforms IEC Coding Type is required for HBR
+		 * support, read current Digital Converter settings and set
+		 * ICT bitfield if needed.
+		 */
+		param = snd_hda_codec_read(codec, cvt_nid, 0,
+					   AC_VERB_GET_DIGI_CONVERT_1, 0);
+
+		param = (param >> 16) & ~(AC_DIG3_ICT);
+
+		/* on recent platforms ICT mode is required for HBR support */
+		if (is_hbr_format(format))
+			param |= 0x1;
+
+		snd_hda_codec_write(codec, cvt_nid, 0,
+				    AC_VERB_SET_DIGI_CONVERT_3, param);
+	}
+
 	snd_hda_codec_setup_stream(codec, cvt_nid, stream_tag, 0, format);
 	return 0;
 }
-- 
2.11.0