Commit 951894cf authored by Harsha Priya's avatar Harsha Priya Committed by Takashi Iwai
Browse files

ALSA: hda/hdmi: Add Intel silent stream support 



External HDMI receivers have analog circuitry that needs to be powered-on
when exiting standby, and a mechanism to detect PCM v. IEC61937 data.
These two steps take time and up to 2-3 seconds of audio may be muted
when starting playback.

Intel hardware (Haswell and beyond) can keep the link active
with a 'silent stream', so that the receiver does not go through those
two steps when valid audio is transmitted. This mechanism relies
on an setting the channel_id as 0xf, sending info packet and preventing
the codec from going to D3,  which will increase the platform
static power consumption. The info packet assumes a basic 2ch stereo,
and the silent stream is enabled when connecting a monitor.
In case of format changes the detection of PCM v. IEC61937 needs to
be re-run. In this case there is no way to avoid the 2-3s mute.

The silent stream is enabled with a Kconfig option, as well as a kernel
parameter should there be a need to override the build time default.
This approach is used based on the power_save capability as an example,
but in the future, it may be used with a kcontrol,
depending on UCM support for HDaudio legacy.

Signed-off-by: default avatarHarsha Priya <harshapriya.n@intel.com>
Signed-off-by: default avatarEmmanuel Jillela <emmanuel.jillela@intel.com>
Reviewed-by: default avatarKai Vehmanen <kai.vehmanen@linux.intel.com>
Reported-by: default avatarkernel test robot <lkp@intel.com>
Link: https://lore.kernel.org/r/1594068797-14011-1-git-send-email-harshapriya.n@intel.com


Signed-off-by: default avatarTakashi Iwai <tiwai@suse.de>
parent ad1e0b7d

sound/pci/hda/Kconfig

+14 −0
Original line number Diff line number Diff line
@@ -240,6 +240,20 @@ config SND_HDA_POWER_SAVE_DEFAULT 
	  The default time-out value in seconds for HD-audio automatic

	  power-save mode.  0 means to disable the power-save mode.



config SND_HDA_INTEL_HDMI_SILENT_STREAM

	bool "Enable Silent Stream always for HDMI"

	depends on SND_HDA_INTEL

	help

	  Intel hardware has a feature called 'silent stream', that

	  keeps external HDMI receiver's analog circuitry powered on

	  avoiding 2-3 sec silence during playback start. This mechanism

	  relies on setting channel_id as 0xf, sending info packet and

	  preventing codec D3 entry (increasing  platform static power

	  consumption when HDMI receiver is plugged-in). 2-3 sec silence

	  at the playback start is expected whenever there is format change.

	  (default is 2 channel format).

	  Say Y to enable Silent Stream feature.



endif



endmenu

sound/pci/hda/patch_hdmi.c

+64 −0
Original line number Diff line number Diff line
@@ -42,6 +42,11 @@ static bool enable_acomp = true; 
module_param(enable_acomp, bool, 0444);

MODULE_PARM_DESC(enable_acomp, "Enable audio component binding (default=yes)");



static bool enable_silent_stream =

IS_ENABLED(CONFIG_SND_HDA_INTEL_HDMI_SILENT_STREAM);

module_param(enable_silent_stream, bool, 0644);

MODULE_PARM_DESC(enable_silent_stream, "Enable Silent Stream for HDMI devices");



struct hdmi_spec_per_cvt {

	hda_nid_t cvt_nid;

	int assigned;
@@ -167,6 +172,7 @@ struct hdmi_spec { 
	hda_nid_t vendor_nid;

	const int *port_map;

	int port_num;

	bool send_silent_stream; /* Flag to enable silent stream feature */

};



#ifdef CONFIG_SND_HDA_COMPONENT
@@ -1634,21 +1640,72 @@ static void hdmi_present_sense_via_verbs(struct hdmi_spec_per_pin *per_pin, 
	snd_hda_power_down_pm(codec);

}



static void silent_stream_enable(struct hda_codec *codec,

				struct hdmi_spec_per_pin *per_pin)

{

	unsigned int newval, oldval;



	codec_dbg(codec, "hdmi: enabling silent stream for NID %d\n",

			per_pin->pin_nid);



	mutex_lock(&per_pin->lock);



	if (!per_pin->channels)

		per_pin->channels = 2;



	oldval = snd_hda_codec_read(codec, per_pin->pin_nid, 0,

			AC_VERB_GET_CONV, 0);

	newval = (oldval & 0xF0) | 0xF;

	snd_hda_codec_write(codec, per_pin->pin_nid, 0,

			AC_VERB_SET_CHANNEL_STREAMID, newval);



	hdmi_setup_audio_infoframe(codec, per_pin, per_pin->non_pcm);



	mutex_unlock(&per_pin->lock);

}



/* update ELD and jack state via audio component */

static void sync_eld_via_acomp(struct hda_codec *codec,

			       struct hdmi_spec_per_pin *per_pin)

{

	struct hdmi_spec *spec = codec->spec;

	struct hdmi_eld *eld = &spec->temp_eld;

	bool monitor_prev, monitor_next;



	mutex_lock(&per_pin->lock);

	eld->monitor_present = false;

	monitor_prev = per_pin->sink_eld.monitor_present;

	eld->eld_size = snd_hdac_acomp_get_eld(&codec->core, per_pin->pin_nid,

				      per_pin->dev_id, &eld->monitor_present,

				      eld->eld_buffer, ELD_MAX_SIZE);

	eld->eld_valid = (eld->eld_size > 0);

	update_eld(codec, per_pin, eld, 0);

	monitor_next = per_pin->sink_eld.monitor_present;

	mutex_unlock(&per_pin->lock);



	/*

	 * Power-up will call hdmi_present_sense, so the PM calls

	 * have to be done without mutex held.

	 */



	if (spec->send_silent_stream) {

		int pm_ret;



		if (!monitor_prev && monitor_next) {

			pm_ret = snd_hda_power_up_pm(codec);

			if (pm_ret < 0)

				codec_err(codec,

				"Monitor plugged-in, Failed to power up codec ret=[%d]\n",

				pm_ret);

			silent_stream_enable(codec, per_pin);

		} else if (monitor_prev && !monitor_next) {

			pm_ret = snd_hda_power_down_pm(codec);

			if (pm_ret < 0)

				codec_err(codec,

				"Monitor plugged-out, Failed to power down codec ret=[%d]\n",

				pm_ret);

		}

	}

}



static void hdmi_present_sense(struct hdmi_spec_per_pin *per_pin, int repoll)
@@ -2791,6 +2848,13 @@ static int intel_hsw_common_init(struct hda_codec *codec, hda_nid_t vendor_nid, 
	spec->ops.setup_stream = i915_hsw_setup_stream;

	spec->ops.pin_cvt_fixup = i915_pin_cvt_fixup;



	/*

	 * Enable silent stream feature, if it is enabled via

	 * module param or Kconfig option

	 */

	if (enable_silent_stream)

		spec->send_silent_stream = true;



	return parse_intel_hdmi(codec);

}

CRA Git | Maintained and supported by SUSTech CRA and CCSE