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Digi 002/003 family uses its own format for data blocks. The format is quite similar to AM824 in IEC 61883-6, while there're some differences: * The Valid Bit Length (VBL) code is always 0x40 in Multi-bit Linear Audio (MBLA) data channel. * The first data channel includes MIDI messages, against IEC 61883-6 recommendation. * The Counter field is always zero in MIDI conformant data channel. * Sequence multiplexing in IEC 61883-6 is not applied to the MIDI conformant data channel. * PCM samples are scrambled in received AMDTP packets. We call the way as Double-Oh-Three (DOT). The algorithm was discovered by Robin Gareus and Damien Zammit in 2012. This commit adds data processing layer to satisfy these differences. There's a quirk about transmission mode for received packets. When this driver applies non-blocking mode to outgoing packets with isochronous channel 2 or more, after 15 to 20 seconds since playbacking, any PCM samples causes noisy sound on the device. With isochronous channel 0 or 1, this doesn't occur. As long as I investigated, this quirk is not observed when applying blocking mode to the received packets. This driver applies blocking mode to outgoing packets, while non-blocking mode to incoming packgets. Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp> Signed-off-by: Takashi Iwai <tiwai@suse.de>
46 lines
1.2 KiB
C
46 lines
1.2 KiB
C
/*
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* digi00x.h - a part of driver for Digidesign Digi 002/003 family
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*
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* Copyright (c) 2014-2015 Takashi Sakamoto
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*
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* Licensed under the terms of the GNU General Public License, version 2.
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*/
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#ifndef SOUND_DIGI00X_H_INCLUDED
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#define SOUND_DIGI00X_H_INCLUDED
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#include <linux/compat.h>
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#include <linux/device.h>
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#include <linux/firewire.h>
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#include <linux/module.h>
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#include <linux/mod_devicetable.h>
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#include <linux/delay.h>
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#include <linux/slab.h>
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#include <sound/core.h>
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#include <sound/initval.h>
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#include <sound/pcm.h>
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#include <sound/pcm_params.h>
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#include "../lib.h"
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#include "../iso-resources.h"
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#include "../amdtp-stream.h"
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struct snd_dg00x {
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struct snd_card *card;
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struct fw_unit *unit;
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struct mutex mutex;
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};
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int amdtp_dot_init(struct amdtp_stream *s, struct fw_unit *unit,
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enum amdtp_stream_direction dir);
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int amdtp_dot_set_parameters(struct amdtp_stream *s, unsigned int rate,
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unsigned int pcm_channels,
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unsigned int midi_ports);
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void amdtp_dot_reset(struct amdtp_stream *s);
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int amdtp_dot_add_pcm_hw_constraints(struct amdtp_stream *s,
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struct snd_pcm_runtime *runtime);
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void amdtp_dot_set_pcm_format(struct amdtp_stream *s, snd_pcm_format_t format);
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#endif
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