From: Libin Yang libin.yang@linux.intel.com
Add the documentation about HD-audio DP MST: 1. Overview 2. Jack
Others will be added later.
Signed-off-by: Libin Yang libin.yang@linux.intel.com --- Documentation/sound/alsa/HD-Audio-DP-MST-audio.txt | 78 ++++++++++++++++++++++ 1 file changed, 78 insertions(+) create mode 100644 Documentation/sound/alsa/HD-Audio-DP-MST-audio.txt
diff --git a/Documentation/sound/alsa/HD-Audio-DP-MST-audio.txt b/Documentation/sound/alsa/HD-Audio-DP-MST-audio.txt new file mode 100644 index 0000000..ff28e55 --- /dev/null +++ b/Documentation/sound/alsa/HD-Audio-DP-MST-audio.txt @@ -0,0 +1,78 @@ +To support DP MST audio, HD Audio hdmi codec driver introduces virtual pin +and dynamic pcm assignment. + +Virtual pin is an extension of per_pin. The most difference of DP MST +from legacy is that DP MST introduces device entry. Each pin can contain +several device entries. Each device entry behaves as a pin. + +As each pin may contain several device entries and each codec may contain +several pins, if we use one pcm per per_pin, there will be many PCMs. +The new solution is to create a few PCMs and to dynamically bind pcm to +per_pin. Driver uses spec->dyn_pcm_assign flag to indicate whether to use +the new solution. + +PCM +=== +To be added + + +Jack +==== + +Presume: + - MST must be dyn_pcm_assign, it can be acomp or !acomp; + - NON-MST may or may not be dyn_pcm_assign, it can be acomp or !acomp; + +So there are the following scenarios: + a.MST (&& dyn_pcm_assign) && acomp + b.MST (&& dyn_pcm_assign) && !acomp + c.NON-MST && dyn_pcm_assign && acomp + d.NON-MST && dyn_pcm_assign && !acomp + e.NON-MST && !dyn_pcm_assign && acomp + f.NON-MST && !dyn_pcm_assign && !acomp + +Below discussion will ignore MST and NON-MST difference as it doesn't +impact on jack handling too much. + +Driver uses new struct hdmi_pcm pcm[] array in hdmi_spec and snd_jack is +a member of hdmi_pcm. Each pin has one struct hdmi_pcm * pcm pointer. + +For !dyn_pcm_assign, per_pin->pcm will assigned to spec->pcm[n] statically. + +For dyn_pcm_assign, per_pin->pcm will assigned to spec->pcm[n] +when monitor is hotplugged. + + +Build Jack +---------- + +Build jack based on the pcm. acomp or !acomp will not impact on jack buiding. +- dyn_pcm_assign +Will not use hda_jack but use snd_jack in spec->pcm_rec[pcm_idx].jack directly. + +- !dyn_pcm_assign +Use hda_jack and assign spec->pcm_rec[pcm_idx].jack = jack->jack statically. + + +Unsolicited Event Enabling +-------------------------- +Enable unsolicited event if !acomp. + + +Monitor Hotplug Event Handling +------------------------------ +- acomp +pin_eld_notify() -> check_presence_and_report() -> hdmi_present_sense() -> +sync_eld_via_acomp(). +Use directly snd_jack_report() on spec->pcm_rec[pcm_idx].jack for +both dyn_pcm_assign and !dyn_pcm_assign + +- !acomp +Hdmi_unsol_event() -> hdmi_intrinsic_event() -> check_presence_and_report() -> +hdmi_present_sense() -> hdmi_prepsent_sense_via_verbs() +Use directly snd_jack_report() on spec->pcm_rec[pcm_idx].jack for dyn_pcm_assign. +Use hda_jack mechanism to handle jack events. + + +Others to be added later +========================