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+=================================
+Notes on Maya44 USB Audio Support
+=================================
+
+.. note::
+   The following is the original document of Rainer's patch that the
+   current maya44 code based on.  Some contents might be obsoleted, but I
+   keep here as reference -- tiwai
+
+Feb 14, 2008
+
+Rainer Zimmermann <mail@lightshed.de>
+ 
+STATE OF DEVELOPMENT
+====================
+
+This driver is being developed on the initiative of Piotr Makowski (oponek@gmail.com) and financed by Lars Bergmann.
+Development is carried out by Rainer Zimmermann (mail@lightshed.de).
+
+ESI provided a sample Maya44 card for the development work.
+
+However, 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.
+
+This is the first testing version of the Maya44 driver released to the alsa-devel mailing list (Feb 5, 2008).
+
+
+The following functions work, as tested by Rainer Zimmermann and Piotr Makowski:
+
+- playback and capture at all sampling rates
+- input/output level
+- crossmixing
+- line/mic switch
+- phantom power switch
+- analogue monitor a.k.a bypass
+
+
+The following functions *should* work, but are not fully tested:
+
+- Channel 3+4 analogue - S/PDIF input switching
+- S/PDIF output
+- all inputs/outputs on the M/IO/DIO extension card
+- internal/external clock selection
+
+
+*In particular, we would appreciate testing of these functions by anyone who has access to an M/IO/DIO extension card.*
+
+
+Things that do not seem to work:
+
+- 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).
+
+- Ardour 2.1 seems to work only via JACK, not using ALSA directly or via OSS. This still needs to be tracked down.
+
+
+DRIVER DETAILS
+==============
+
+the following files were added:
+
+* pci/ice1724/maya44.c - Maya44 specific code
+* pci/ice1724/maya44.h
+* pci/ice1724/ice1724.patch
+* pci/ice1724/ice1724.h.patch - PROPOSED patch to ice1724.h (see SAMPLING RATES)
+* i2c/other/wm8776.c - low-level access routines for Wolfson WM8776 codecs 
+* include/wm8776.h
+
+
+Note that the wm8776.c code is meant to be card-independent and does not actually register the codec with the ALSA infrastructure.
+This is done in maya44.c, mainly because some of the WM8776 controls are used in Maya44-specific ways, and should be named appropriately.
+
+
+the following files were created in pci/ice1724, simply #including the corresponding file from the alsa-kernel tree:
+
+* wtm.h
+* vt1720_mobo.h
+* revo.h
+* prodigy192.h
+* pontis.h
+* phase.h
+* maya44.h
+* juli.h
+* aureon.h
+* amp.h
+* envy24ht.h
+* se.h
+* prodigy_hifi.h
+
+
+*I hope this is the correct way to do things.*
+
+
+SAMPLING RATES
+==============
+
+The Maya44 card (or more exactly, the Wolfson WM8776 codecs) allow a maximum sampling rate of 192 kHz for playback and 92 kHz for capture.
+
+As the ICE1724 chip only allows one global sampling rate, this is handled as follows:
+
+* 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.
+
+* In the current state of the driver, setting rates of up to 192 kHz is permitted even for capture devices.
+
+*AVOID CAPTURING AT RATES ABOVE 96kHz*, even though it may appear to work. The codec cannot actually capture at such rates, meaning poor quality.
+
+
+I 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.
+
+The proposed code (currently deactivated) is in ice1712.h.patch, ice1724.c and maya44.c (in pci/ice1712).
+
+
+SOUND DEVICES
+=============
+
+PCM devices correspond to inputs/outputs as follows (assuming Maya44 is card #0):
+
+* hw:0,0 input - stereo, analog input 1+2
+* hw:0,0 output - stereo, analog output 1+2
+* hw:0,1 input - stereo, analog input 3+4 OR S/PDIF input
+* hw:0,1 output - stereo, analog output 3+4 (and SPDIF out)
+
+
+NAMING OF MIXER CONTROLS
+========================
+
+(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).
+
+
+PCM
+    (digital) output level for channel 1+2
+PCM 1
+    same for channel 3+4
+
+Mic Phantom+48V
+    switch for +48V phantom power for electrostatic microphones on input 1/2.
+
+    Make sure this is not turned on while any other source is connected to input 1/2.
+    It might damage the source and/or the maya44 card.
+
+Mic/Line input
+    if switch is on, input jack 1/2 is microphone input (mono), otherwise line input (stereo).
+
+Bypass
+    analogue bypass from ADC input to output for channel 1+2. Same as "Monitor" in the windows driver.
+Bypass 1
+    same for channel 3+4.
+
+Crossmix
+    cross-mixer from channels 1+2 to channels 3+4
+Crossmix 1
+    cross-mixer from channels 3+4 to channels 1+2
+
+IEC958 Output
+    switch for S/PDIF output.
+
+    This is not supported by the ESI windows driver.
+    S/PDIF should output the same signal as channel 3+4. [untested!]
+
+
+Digitial output selectors
+    These switches allow a direct digital routing from the ADCs to the DACs.
+    Each switch determines where the digital input data to one of the DACs comes from.
+    They are not supported by the ESI windows driver.
+    For normal operation, they should all be set to "PCM out".
+
+H/W
+    Output source channel 1
+H/W 1
+    Output source channel 2
+H/W 2
+    Output source channel 3
+H/W 3
+    Output source channel 4
+
+H/W 4 ... H/W 9
+    unknown function, left in to enable testing.
+
+    Possibly some of these control S/PDIF output(s).
+    If these turn out to be unused, they will go away in later driver versions.
+
+Selectable values for each of the digital output selectors are:
+
+PCM out
+	DAC output of the corresponding channel (default setting)
+Input 1 ... Input 4
+	direct routing from ADC output of the selected input channel
+