102 lines
3.0 KiB
ReStructuredText
102 lines
3.0 KiB
ReStructuredText
=======================
|
|
HD-Audio DP-MST Support
|
|
=======================
|
|
|
|
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
|
|
|
|
Pin Initialization
|
|
==================
|
|
Each pin may have several device entries (virtual pins). On Intel platform,
|
|
the device entries number is dynamically changed. If DP MST hub is connected,
|
|
it is in DP MST mode, and the device entries number is 3. Otherwise, the
|
|
device entries number is 1.
|
|
|
|
To simplify the implementation, all the device entries will be initialized
|
|
when bootup no matter whether it is in DP MST mode or not.
|
|
|
|
Connection list
|
|
===============
|
|
DP MST reuses connection list code. The code can be reused because
|
|
device entries on the same pin have the same connection list.
|
|
|
|
This means DP MST gets the device entry connection list without the
|
|
device entry setting.
|
|
|
|
Jack
|
|
====
|
|
|
|
Presume:
|
|
- MST must be dyn_pcm_assign, and it is acomp (for Intel scenario);
|
|
- 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. NON-MST && dyn_pcm_assign && acomp
|
|
c. 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 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
|
|
----------
|
|
|
|
- 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
|
|
========================
|