51c29fd213
The value of FDF field in CIP header is protocol-dependent. Thus, it's better to allow data block processing layer to decide the value in any timing. In AM824 data format, the value of FDF field in CIP header indicates N-flag and Nominal Sampling Frequency Code (sfc). The N-flag is for switching 'Clock-based rate control mode' and 'Command-based rate control mode'. In our implementation, 'Clock-based rate control mode' is just supported. Therefore, When sampling transfer frequency is decided, then the FDF can be set. This commit replaces 'amdtp_stream_set_parameters' with 'amdtp_am824_set_parameters' to set the FDF. This is the same timing to decide the ration between the number of data blocks and the number of PCM frames. Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp> Signed-off-by: Takashi Iwai <tiwai@suse.de>
69 lines
2.0 KiB
C
69 lines
2.0 KiB
C
/*
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* AM824 format in Audio and Music Data Transmission Protocol (IEC 61883-6)
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*
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* Copyright (c) 2015 Takashi Sakamoto <o-takashi@sakamocchi.jp>
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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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#include "amdtp-am824.h"
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#define CIP_FMT_AM 0x10
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/* "Clock-based rate control mode" is just supported. */
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#define AMDTP_FDF_AM824 0x00
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/**
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* amdtp_am824_set_parameters - set stream parameters
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* @s: the AMDTP stream to configure
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* @rate: the sample rate
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* @pcm_channels: the number of PCM samples in each data block, to be encoded
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* as AM824 multi-bit linear audio
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* @midi_ports: the number of MIDI ports (i.e., MPX-MIDI Data Channels)
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* @double_pcm_frames: one data block transfers two PCM frames
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*
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* The parameters must be set before the stream is started, and must not be
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* changed while the stream is running.
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*/
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int amdtp_am824_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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bool double_pcm_frames)
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{
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int err;
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err = amdtp_stream_set_parameters(s, rate, pcm_channels, midi_ports);
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if (err < 0)
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return err;
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s->fdf = AMDTP_FDF_AM824 | s->sfc;
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/*
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* In IEC 61883-6, one data block represents one event. In ALSA, one
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* event equals to one PCM frame. But Dice has a quirk at higher
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* sampling rate to transfer two PCM frames in one data block.
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*/
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if (double_pcm_frames)
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s->frame_multiplier = 2;
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else
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s->frame_multiplier = 1;
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return 0;
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}
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EXPORT_SYMBOL_GPL(amdtp_am824_set_parameters);
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/**
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* amdtp_am824_init - initialize an AMDTP stream structure to handle AM824
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* data block
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* @s: the AMDTP stream to initialize
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* @unit: the target of the stream
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* @dir: the direction of stream
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* @flags: the packet transmission method to use
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*/
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int amdtp_am824_init(struct amdtp_stream *s, struct fw_unit *unit,
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enum amdtp_stream_direction dir, enum cip_flags flags)
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{
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return amdtp_stream_init(s, unit, dir, flags, CIP_FMT_AM);
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}
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EXPORT_SYMBOL_GPL(amdtp_am824_init);
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