1 ======================= 1 =======================
2 HD-Audio DP-MST Support 2 HD-Audio DP-MST Support
3 ======================= 3 =======================
4 4
5 To support DP MST audio, HD Audio hdmi codec d 5 To support DP MST audio, HD Audio hdmi codec driver introduces virtual pin
6 and dynamic pcm assignment. 6 and dynamic pcm assignment.
7 7
8 Virtual pin is an extension of per_pin. The mo 8 Virtual pin is an extension of per_pin. The most difference of DP MST
9 from legacy is that DP MST introduces device e 9 from legacy is that DP MST introduces device entry. Each pin can contain
10 several device entries. Each device entry beha 10 several device entries. Each device entry behaves as a pin.
11 11
12 As each pin may contain several device entries 12 As each pin may contain several device entries and each codec may contain
13 several pins, if we use one pcm per per_pin, t 13 several pins, if we use one pcm per per_pin, there will be many PCMs.
14 The new solution is to create a few PCMs and t 14 The new solution is to create a few PCMs and to dynamically bind pcm to
15 per_pin. Driver uses spec->dyn_pcm_assign flag 15 per_pin. Driver uses spec->dyn_pcm_assign flag to indicate whether to use
16 the new solution. 16 the new solution.
17 17
18 PCM 18 PCM
19 === 19 ===
20 To be added 20 To be added
21 21
22 Pin Initialization 22 Pin Initialization
23 ================== 23 ==================
24 Each pin may have several device entries (virt 24 Each pin may have several device entries (virtual pins). On Intel platform,
25 the device entries number is dynamically chang 25 the device entries number is dynamically changed. If DP MST hub is connected,
26 it is in DP MST mode, and the device entries n 26 it is in DP MST mode, and the device entries number is 3. Otherwise, the
27 device entries number is 1. 27 device entries number is 1.
28 28
29 To simplify the implementation, all the device 29 To simplify the implementation, all the device entries will be initialized
30 when bootup no matter whether it is in DP MST 30 when bootup no matter whether it is in DP MST mode or not.
31 31
32 Connection list 32 Connection list
33 =============== 33 ===============
34 DP MST reuses connection list code. The code c 34 DP MST reuses connection list code. The code can be reused because
35 device entries on the same pin have the same c 35 device entries on the same pin have the same connection list.
36 36
37 This means DP MST gets the device entry connec 37 This means DP MST gets the device entry connection list without the
38 device entry setting. 38 device entry setting.
39 39
40 Jack 40 Jack
41 ==== 41 ====
42 42
43 Presume: 43 Presume:
44 - MST must be dyn_pcm_assign, and it is acomp 44 - MST must be dyn_pcm_assign, and it is acomp (for Intel scenario);
45 - NON-MST may or may not be dyn_pcm_assign, i 45 - NON-MST may or may not be dyn_pcm_assign, it can be acomp or !acomp;
46 46
47 So there are the following scenarios: 47 So there are the following scenarios:
48 a. MST (&& dyn_pcm_assign && acomp) 48 a. MST (&& dyn_pcm_assign && acomp)
49 b. NON-MST && dyn_pcm_assign && acomp 49 b. NON-MST && dyn_pcm_assign && acomp
50 c. NON-MST && !dyn_pcm_assign && !acomp 50 c. NON-MST && !dyn_pcm_assign && !acomp
51 51
52 Below discussion will ignore MST and NON-MST d 52 Below discussion will ignore MST and NON-MST difference as it doesn't
53 impact on jack handling too much. 53 impact on jack handling too much.
54 54
55 Driver uses struct hdmi_pcm pcm[] array in hdm 55 Driver uses struct hdmi_pcm pcm[] array in hdmi_spec and snd_jack is
56 a member of hdmi_pcm. Each pin has one struct 56 a member of hdmi_pcm. Each pin has one struct hdmi_pcm * pcm pointer.
57 57
58 For !dyn_pcm_assign, per_pin->pcm will assigne 58 For !dyn_pcm_assign, per_pin->pcm will assigned to spec->pcm[n] statically.
59 59
60 For dyn_pcm_assign, per_pin->pcm will assigned 60 For dyn_pcm_assign, per_pin->pcm will assigned to spec->pcm[n]
61 when monitor is hotplugged. 61 when monitor is hotplugged.
62 62
63 63
64 Build Jack 64 Build Jack
65 ---------- 65 ----------
66 66
67 - dyn_pcm_assign 67 - dyn_pcm_assign
68 68
69 Will not use hda_jack but use snd_jack in sp 69 Will not use hda_jack but use snd_jack in spec->pcm_rec[pcm_idx].jack directly.
70 70
71 - !dyn_pcm_assign 71 - !dyn_pcm_assign
72 72
73 Use hda_jack and assign spec->pcm_rec[pcm_id 73 Use hda_jack and assign spec->pcm_rec[pcm_idx].jack = jack->jack statically.
74 74
75 75
76 Unsolicited Event Enabling 76 Unsolicited Event Enabling
77 -------------------------- 77 --------------------------
78 Enable unsolicited event if !acomp. 78 Enable unsolicited event if !acomp.
79 79
80 80
81 Monitor Hotplug Event Handling 81 Monitor Hotplug Event Handling
82 ------------------------------ 82 ------------------------------
83 - acomp 83 - acomp
84 84
85 pin_eld_notify() -> check_presence_and_repor 85 pin_eld_notify() -> check_presence_and_report() -> hdmi_present_sense() ->
86 sync_eld_via_acomp(). 86 sync_eld_via_acomp().
87 87
88 Use directly snd_jack_report() on spec->pcm_ 88 Use directly snd_jack_report() on spec->pcm_rec[pcm_idx].jack for
89 both dyn_pcm_assign and !dyn_pcm_assign 89 both dyn_pcm_assign and !dyn_pcm_assign
90 90
91 - !acomp 91 - !acomp
92 92
93 hdmi_unsol_event() -> hdmi_intrinsic_event() 93 hdmi_unsol_event() -> hdmi_intrinsic_event() -> check_presence_and_report() ->
94 hdmi_present_sense() -> hdmi_prepsent_sense_ 94 hdmi_present_sense() -> hdmi_prepsent_sense_via_verbs()
95 95
96 Use directly snd_jack_report() on spec->pcm_ 96 Use directly snd_jack_report() on spec->pcm_rec[pcm_idx].jack for dyn_pcm_assign.
97 Use hda_jack mechanism to handle jack events 97 Use hda_jack mechanism to handle jack events.
98 98
99 99
100 Others to be added later 100 Others to be added later
101 ======================== 101 ========================
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