sound/firewire/bebob/bebob_yamaha.c

   1 /*
   2  * bebob_yamaha.c - a part of driver for BeBoB based devices
   3  *
   4  * Copyright (c) 2013-2014 Takashi Sakamoto
   5  *
   6  * Licensed under the terms of the GNU General Public License, version 2.
   7  */
   8
   9 #include "./bebob.h"
  10
  11 /*
  12  * NOTE:
  13  * Yamaha GO44 is not designed to be used as stand-alone mixer. So any streams
  14  * must be accompanied. If changing the state, a LED on the device starts to
  15  * blink and its sync status is false. In this state, the device sounds nothing
  16  * even if streaming. To start streaming at the current sampling rate is only
  17  * way to revocer this state. GO46 is better for stand-alone mixer.
  18  *
  19  * Both of them have a capability to change its sampling rate up to 192.0kHz.
  20  * At 192.0kHz, the device reports 4 PCM-in, 1 MIDI-in, 6 PCM-out, 1 MIDI-out.
  21  * But Yamaha's driver reduce 2 PCM-in, 1 MIDI-in, 2 PCM-out, 1 MIDI-out to use
  22  * 'Extended Stream Format Information Command - Single Request' in 'Additional
  23  * AVC commands' defined by BridgeCo.
  24  * This ALSA driver don't do this because a bit tiresome. Then isochronous
  25  * streaming with many asynchronous transactions brings sounds with noises.
  26  * Unfortunately current 'ffado-mixer' generated many asynchronous transaction
  27  * to observe device's state, mainly check cmp connection and signal format. I
  28  * reccomend users to close ffado-mixer at 192.0kHz if mixer is needless.
  29  */
  30
  31 static enum snd_bebob_clock_type clk_src_types[] = {
  32         SND_BEBOB_CLOCK_TYPE_INTERNAL,
  33         SND_BEBOB_CLOCK_TYPE_EXTERNAL,  /* S/PDIF */
  34 };
  35 static int
  36 clk_src_get(struct snd_bebob *bebob, unsigned int *id)
  37 {
  38         int err;
  39
  40         err = avc_audio_get_selector(bebob->unit, 0, 4, id);
  41         if (err < 0)
  42                 return err;
  43
  44         if (*id >= ARRAY_SIZE(clk_src_types))
  45                 return -EIO;
  46
  47         return 0;
  48 }
  49 static const struct snd_bebob_clock_spec clock_spec = {
  50         .num    = ARRAY_SIZE(clk_src_types),
  51         .types  = clk_src_types,
  52         .get    = &clk_src_get,
  53 };
  54 static const struct snd_bebob_rate_spec rate_spec = {
  55         .get    = &snd_bebob_stream_get_rate,
  56         .set    = &snd_bebob_stream_set_rate,
  57 };
  58 const struct snd_bebob_spec yamaha_go_spec = {
  59         .clock  = &clock_spec,
  60         .rate   = &rate_spec,
  61         .meter  = NULL
  62 };