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