1=================================
2Notes on Maya44 USB Audio Support
3=================================
4
5.. note::
6   The following is the original document of Rainer's patch that the
7   current maya44 code based on.  Some contents might be obsoleted, but I
8   keep here as reference -- tiwai
9
10Feb 14, 2008
11
12Rainer Zimmermann <mail@lightshed.de>
13
14STATE OF DEVELOPMENT
15====================
16
17This driver is being developed on the initiative of Piotr Makowski (oponek@gmail.com) and financed by Lars Bergmann.
18Development is carried out by Rainer Zimmermann (mail@lightshed.de).
19
20ESI provided a sample Maya44 card for the development work.
21
22However, unfortunately it has turned out difficult to get detailed programming information, so I (Rainer Zimmermann) had to find out some card-specific information by experiment and conjecture. Some information (in particular, several GPIO bits) is still missing.
23
24This is the first testing version of the Maya44 driver released to the alsa-devel mailing list (Feb 5, 2008).
25
26
27The following functions work, as tested by Rainer Zimmermann and Piotr Makowski:
28
29- playback and capture at all sampling rates
30- input/output level
31- crossmixing
32- line/mic switch
33- phantom power switch
34- analogue monitor a.k.a bypass
35
36
37The following functions *should* work, but are not fully tested:
38
39- Channel 3+4 analogue - S/PDIF input switching
40- S/PDIF output
41- all inputs/outputs on the M/IO/DIO extension card
42- internal/external clock selection
43
44
45*In particular, we would appreciate testing of these functions by anyone who has access to an M/IO/DIO extension card.*
46
47
48Things that do not seem to work:
49
50- The level meters ("multi track") in 'alsamixer' do not seem to react to signals in (if this is a bug, it would probably be in the existing ICE1724 code).
51
52- Ardour 2.1 seems to work only via JACK, not using ALSA directly or via OSS. This still needs to be tracked down.
53
54
55DRIVER DETAILS
56==============
57
58the following files were added:
59
60* pci/ice1724/maya44.c - Maya44 specific code
61* pci/ice1724/maya44.h
62* pci/ice1724/ice1724.patch
63* pci/ice1724/ice1724.h.patch - PROPOSED patch to ice1724.h (see SAMPLING RATES)
64* i2c/other/wm8776.c - low-level access routines for Wolfson WM8776 codecs
65* include/wm8776.h
66
67
68Note that the wm8776.c code is meant to be card-independent and does not actually register the codec with the ALSA infrastructure.
69This is done in maya44.c, mainly because some of the WM8776 controls are used in Maya44-specific ways, and should be named appropriately.
70
71
72the following files were created in pci/ice1724, simply #including the corresponding file from the alsa-kernel tree:
73
74* wtm.h
75* vt1720_mobo.h
76* revo.h
77* prodigy192.h
78* pontis.h
79* phase.h
80* maya44.h
81* juli.h
82* aureon.h
83* amp.h
84* envy24ht.h
85* se.h
86* prodigy_hifi.h
87
88
89*I hope this is the correct way to do things.*
90
91
92SAMPLING RATES
93==============
94
95The Maya44 card (or more exactly, the Wolfson WM8776 codecs) allow a maximum sampling rate of 192 kHz for playback and 92 kHz for capture.
96
97As the ICE1724 chip only allows one global sampling rate, this is handled as follows:
98
99* setting the sampling rate on any open PCM device on the maya44 card will always set the *global* sampling rate for all playback and capture channels.
100
101* In the current state of the driver, setting rates of up to 192 kHz is permitted even for capture devices.
102
103*AVOID CAPTURING AT RATES ABOVE 96kHz*, even though it may appear to work. The codec cannot actually capture at such rates, meaning poor quality.
104
105
106I propose some additional code for limiting the sampling rate when setting on a capture pcm device. However because of the global sampling rate, this logic would be somewhat problematic.
107
108The proposed code (currently deactivated) is in ice1712.h.patch, ice1724.c and maya44.c (in pci/ice1712).
109
110
111SOUND DEVICES
112=============
113
114PCM devices correspond to inputs/outputs as follows (assuming Maya44 is card #0):
115
116* hw:0,0 input - stereo, analog input 1+2
117* hw:0,0 output - stereo, analog output 1+2
118* hw:0,1 input - stereo, analog input 3+4 OR S/PDIF input
119* hw:0,1 output - stereo, analog output 3+4 (and SPDIF out)
120
121
122NAMING OF MIXER CONTROLS
123========================
124
125(for more information about the signal flow, please refer to the block diagram on p.24 of the ESI Maya44 manual, or in the ESI windows software).
126
127
128PCM
129    (digital) output level for channel 1+2
130PCM 1
131    same for channel 3+4
132
133Mic Phantom+48V
134    switch for +48V phantom power for electrostatic microphones on input 1/2.
135
136    Make sure this is not turned on while any other source is connected to input 1/2.
137    It might damage the source and/or the maya44 card.
138
139Mic/Line input
140    if switch is on, input jack 1/2 is microphone input (mono), otherwise line input (stereo).
141
142Bypass
143    analogue bypass from ADC input to output for channel 1+2. Same as "Monitor" in the windows driver.
144Bypass 1
145    same for channel 3+4.
146
147Crossmix
148    cross-mixer from channels 1+2 to channels 3+4
149Crossmix 1
150    cross-mixer from channels 3+4 to channels 1+2
151
152IEC958 Output
153    switch for S/PDIF output.
154
155    This is not supported by the ESI windows driver.
156    S/PDIF should output the same signal as channel 3+4. [untested!]
157
158
159Digitial output selectors
160    These switches allow a direct digital routing from the ADCs to the DACs.
161    Each switch determines where the digital input data to one of the DACs comes from.
162    They are not supported by the ESI windows driver.
163    For normal operation, they should all be set to "PCM out".
164
165H/W
166    Output source channel 1
167H/W 1
168    Output source channel 2
169H/W 2
170    Output source channel 3
171H/W 3
172    Output source channel 4
173
174H/W 4 ... H/W 9
175    unknown function, left in to enable testing.
176
177    Possibly some of these control S/PDIF output(s).
178    If these turn out to be unused, they will go away in later driver versions.
179
180Selectable values for each of the digital output selectors are:
181
182PCM out
183	DAC output of the corresponding channel (default setting)
184Input 1 ... Input 4
185	direct routing from ADC output of the selected input channel
186
187