[PATCH] ALSA: hda/hdmi: Add Intel silent stream support

[Pierre-Louis Bossart]

2 nit-picks that I missed in previous versions of this patch, sorry:

> diff --git a/sound/pci/hda/Kconfig b/sound/pci/hda/Kconfig
> index 7ba542e45a3d..8804808410b3 100644
> --- a/sound/pci/hda/Kconfig
> +++ b/sound/pci/hda/Kconfig
> @@ -232,4 +232,20 @@ config SND_HDA_POWER_SAVE_DEFAULT
>   
>   endif
>   
> +config SND_HDA_INTEL_HDMI_SILENT_STREAM
> +	bool "Enable Silent Stream always for HDMI"
> +	depends on SND_HDA

nit-pick: should this be 'depends on SND_HDA_INTEL'?
if not, this 'depends on SND_HDA' is redundant, already within an
'if SND_HDA' block

> +	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 an info packet and preventing the codec from going to
> +	  D3. (increasing the platform static power consumption when a
> +	  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
> +

[...]

>   /* 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 (enable_silent_stream) {
> +		if (!monitor_prev && monitor_next) {
> +			snd_hda_power_up_pm(codec);

nit-pick: is there a need to test the return value? I see this in 
patch_hdmi.c

	ret = snd_hda_power_up_pm(codec);
	if (ret < 0 && pm_runtime_suspended(hda_codec_dev(codec)))
		goto out;

> +			silent_stream_enable(codec, per_pin);
> +		} else if (monitor_prev && !monitor_next)
> +			snd_hda_power_down_pm(codec);
> +	}
>   }
>   
>   static void hdmi_present_sense(struct hdmi_spec_per_pin *per_pin, int repoll)
>