sound/firewire/fireface/ff-pcm.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0-only
 /*
  * ff-pcm.c - a part of driver for RME Fireface series
  *
  * Copyright (c) 2015-2017 Takashi Sakamoto
  */

 #include "ff.h"

 static int hw_rule_rate(struct snd_pcm_hw_params *params,
 			struct snd_pcm_hw_rule *rule)
 {
 	const unsigned int *pcm_channels = rule->private;
 	struct snd_interval *r =
 		hw_param_interval(params, SNDRV_PCM_HW_PARAM_RATE);
 	const struct snd_interval *c =
 		hw_param_interval_c(params, SNDRV_PCM_HW_PARAM_CHANNELS);
 	struct snd_interval t = {
 		.min = UINT_MAX, .max = 0, .integer = 1
 	};
 	unsigned int i;

 	for (i = 0; i < ARRAY_SIZE(amdtp_rate_table); i++) {
 		enum snd_ff_stream_mode mode;
 		int err;

 		err = snd_ff_stream_get_multiplier_mode(i, &mode);
 		if (err < 0)
 			continue;

 		if (!snd_interval_test(c, pcm_channels[mode]))
 			continue;

 		t.min = min(t.min, amdtp_rate_table[i]);
 		t.max = max(t.max, amdtp_rate_table[i]);
 	}

 	return snd_interval_refine(r, &t);
 }

 static int hw_rule_channels(struct snd_pcm_hw_params *params,
 			    struct snd_pcm_hw_rule *rule)
 {
 	const unsigned int *pcm_channels = rule->private;
 	struct snd_interval *c =
 		hw_param_interval(params, SNDRV_PCM_HW_PARAM_CHANNELS);
 	const struct snd_interval *r =
 		hw_param_interval_c(params, SNDRV_PCM_HW_PARAM_RATE);
 	struct snd_interval t = {
 		.min = UINT_MAX, .max = 0, .integer = 1
 	};
 	unsigned int i;

 	for (i = 0; i < ARRAY_SIZE(amdtp_rate_table); i++) {
 		enum snd_ff_stream_mode mode;
 		int err;

 		err = snd_ff_stream_get_multiplier_mode(i, &mode);
 		if (err < 0)
 			continue;

 		if (!snd_interval_test(r, amdtp_rate_table[i]))
 			continue;

 		t.min = min(t.min, pcm_channels[mode]);
 		t.max = max(t.max, pcm_channels[mode]);
 	}

 	return snd_interval_refine(c, &t);
 }

 static void limit_channels_and_rates(struct snd_pcm_hardware *hw,
 				     const unsigned int *pcm_channels)
 {
 	unsigned int rate, channels;
 	int i;

 	hw->channels_min = UINT_MAX;
 	hw->channels_max = 0;
 	hw->rate_min = UINT_MAX;
 	hw->rate_max = 0;

 	for (i = 0; i < ARRAY_SIZE(amdtp_rate_table); i++) {
 		enum snd_ff_stream_mode mode;
 		int err;

 		err = snd_ff_stream_get_multiplier_mode(i, &mode);
 		if (err < 0)
 			continue;

 		channels = pcm_channels[mode];
 		if (pcm_channels[mode] == 0)
 			continue;
 		hw->channels_min = min(hw->channels_min, channels);
 		hw->channels_max = max(hw->channels_max, channels);

 		rate = amdtp_rate_table[i];
 		hw->rates |= snd_pcm_rate_to_rate_bit(rate);
 		hw->rate_min = min(hw->rate_min, rate);
 		hw->rate_max = max(hw->rate_max, rate);
 	}
 }

 static int pcm_init_hw_params(struct snd_ff *ff,
 			      struct snd_pcm_substream *substream)
 {
 	struct snd_pcm_runtime *runtime = substream->runtime;
 	struct amdtp_stream *s;
 	const unsigned int *pcm_channels;
 	int err;

 	if (substream->stream == SNDRV_PCM_STREAM_CAPTURE) {
 		runtime->hw.formats = SNDRV_PCM_FMTBIT_S32;
 		s = &ff->tx_stream;
 		pcm_channels = ff->spec->pcm_capture_channels;
 	} else {
 		runtime->hw.formats = SNDRV_PCM_FMTBIT_S32;
 		s = &ff->rx_stream;
 		pcm_channels = ff->spec->pcm_playback_channels;
 	}

 	limit_channels_and_rates(&runtime->hw, pcm_channels);

 	err = snd_pcm_hw_rule_add(runtime, 0, SNDRV_PCM_HW_PARAM_CHANNELS,
 				  hw_rule_channels, (void *)pcm_channels,
 				  SNDRV_PCM_HW_PARAM_RATE, -1);
 	if (err < 0)
 		return err;

 	err = snd_pcm_hw_rule_add(runtime, 0, SNDRV_PCM_HW_PARAM_RATE,
 				  hw_rule_rate, (void *)pcm_channels,
 				  SNDRV_PCM_HW_PARAM_CHANNELS, -1);
 	if (err < 0)
 		return err;

 	return amdtp_ff_add_pcm_hw_constraints(s, runtime);
 }

 static int pcm_open(struct snd_pcm_substream *substream)
 {
 	struct snd_ff *ff = substream->private_data;
 	struct amdtp_domain *d = &ff->domain;
 	unsigned int rate;
 	enum snd_ff_clock_src src;
 	int i, err;

 	err = snd_ff_stream_lock_try(ff);
 	if (err < 0)
 		return err;

 	err = pcm_init_hw_params(ff, substream);
 	if (err < 0)
 		goto release_lock;

 	err = ff->spec->protocol->get_clock(ff, &rate, &src);
 	if (err < 0)
 		goto release_lock;

 	mutex_lock(&ff->mutex);

 	// When source of clock is not internal or any stream is reserved for
 	// transmission of PCM frames, the available sampling rate is limited
 	// at current one.
 	if (src != SND_FF_CLOCK_SRC_INTERNAL) {
 		for (i = 0; i < CIP_SFC_COUNT; ++i) {
 			if (amdtp_rate_table[i] == rate)
 				break;
 		}

 		// The unit is configured at sampling frequency which packet
 		// streaming engine can't support.
 		if (i >= CIP_SFC_COUNT) {
 			mutex_unlock(&ff->mutex);
 			err = -EIO;
 			goto release_lock;
 		}

 		substream->runtime->hw.rate_min = rate;
 		substream->runtime->hw.rate_max = rate;
 	} else {
 		if (ff->substreams_counter > 0) {
 			unsigned int frames_per_period = d->events_per_period;
 			unsigned int frames_per_buffer = d->events_per_buffer;

 			rate = amdtp_rate_table[ff->rx_stream.sfc];
 			substream->runtime->hw.rate_min = rate;
 			substream->runtime->hw.rate_max = rate;

 			err = snd_pcm_hw_constraint_minmax(substream->runtime,
 					SNDRV_PCM_HW_PARAM_PERIOD_SIZE,
 					frames_per_period, frames_per_period);
 			if (err < 0) {
 				mutex_unlock(&ff->mutex);
 				goto release_lock;
 			}

 			err = snd_pcm_hw_constraint_minmax(substream->runtime,
 					SNDRV_PCM_HW_PARAM_BUFFER_SIZE,
 					frames_per_buffer, frames_per_buffer);
 			if (err < 0) {
 				mutex_unlock(&ff->mutex);
 				goto release_lock;
 			}
 		}
 	}

 	mutex_unlock(&ff->mutex);

 	snd_pcm_set_sync(substream);

 	return 0;

 release_lock:
 	snd_ff_stream_lock_release(ff);
 	return err;
 }

 static int pcm_close(struct snd_pcm_substream *substream)
 {
 	struct snd_ff *ff = substream->private_data;

 	snd_ff_stream_lock_release(ff);

 	return 0;
 }

 static int pcm_hw_params(struct snd_pcm_substream *substream,
 			 struct snd_pcm_hw_params *hw_params)
 {
 	struct snd_ff *ff = substream->private_data;
 	int err = 0;

 	if (substream->runtime->state == SNDRV_PCM_STATE_OPEN) {
 		unsigned int rate = params_rate(hw_params);
 		unsigned int frames_per_period = params_period_size(hw_params);
 		unsigned int frames_per_buffer = params_buffer_size(hw_params);

 		mutex_lock(&ff->mutex);
 		err = snd_ff_stream_reserve_duplex(ff, rate, frames_per_period,
 						   frames_per_buffer);
 		if (err >= 0)
 			++ff->substreams_counter;
 		mutex_unlock(&ff->mutex);
 	}

 	return err;
 }

 static int pcm_hw_free(struct snd_pcm_substream *substream)
 {
 	struct snd_ff *ff = substream->private_data;

 	mutex_lock(&ff->mutex);

 	if (substream->runtime->state != SNDRV_PCM_STATE_OPEN)
 		--ff->substreams_counter;

 	snd_ff_stream_stop_duplex(ff);

 	mutex_unlock(&ff->mutex);

 	return 0;
 }

 static int pcm_capture_prepare(struct snd_pcm_substream *substream)
 {
 	struct snd_ff *ff = substream->private_data;
 	struct snd_pcm_runtime *runtime = substream->runtime;
 	int err;

 	mutex_lock(&ff->mutex);

 	err = snd_ff_stream_start_duplex(ff, runtime->rate);
 	if (err >= 0)
 		amdtp_stream_pcm_prepare(&ff->tx_stream);

 	mutex_unlock(&ff->mutex);

 	return err;
 }

 static int pcm_playback_prepare(struct snd_pcm_substream *substream)
 {
 	struct snd_ff *ff = substream->private_data;
 	struct snd_pcm_runtime *runtime = substream->runtime;
 	int err;

 	mutex_lock(&ff->mutex);

 	err = snd_ff_stream_start_duplex(ff, runtime->rate);
 	if (err >= 0)
 		amdtp_stream_pcm_prepare(&ff->rx_stream);

 	mutex_unlock(&ff->mutex);

 	return err;
 }

 static int pcm_capture_trigger(struct snd_pcm_substream *substream, int cmd)
 {
 	struct snd_ff *ff = substream->private_data;

 	switch (cmd) {
 	case SNDRV_PCM_TRIGGER_START:
 		amdtp_stream_pcm_trigger(&ff->tx_stream, substream);
 		break;
 	case SNDRV_PCM_TRIGGER_STOP:
 		amdtp_stream_pcm_trigger(&ff->tx_stream, NULL);
 		break;
 	default:
 		return -EINVAL;
 	}

 	return 0;
 }

 static int pcm_playback_trigger(struct snd_pcm_substream *substream, int cmd)
 {
 	struct snd_ff *ff = substream->private_data;

 	switch (cmd) {
 	case SNDRV_PCM_TRIGGER_START:
 		amdtp_stream_pcm_trigger(&ff->rx_stream, substream);
 		break;
 	case SNDRV_PCM_TRIGGER_STOP:
 		amdtp_stream_pcm_trigger(&ff->rx_stream, NULL);
 		break;
 	default:
 		return -EINVAL;
 	}

 	return 0;
 }

 static snd_pcm_uframes_t pcm_capture_pointer(struct snd_pcm_substream *sbstrm)
 {
 	struct snd_ff *ff = sbstrm->private_data;

 	return amdtp_domain_stream_pcm_pointer(&ff->domain, &ff->tx_stream);
 }

 static snd_pcm_uframes_t pcm_playback_pointer(struct snd_pcm_substream *sbstrm)
 {
 	struct snd_ff *ff = sbstrm->private_data;

 	return amdtp_domain_stream_pcm_pointer(&ff->domain, &ff->rx_stream);
 }

 static int pcm_capture_ack(struct snd_pcm_substream *substream)
 {
 	struct snd_ff *ff = substream->private_data;

 	return amdtp_domain_stream_pcm_ack(&ff->domain, &ff->tx_stream);
 }

 static int pcm_playback_ack(struct snd_pcm_substream *substream)
 {
 	struct snd_ff *ff = substream->private_data;

 	return amdtp_domain_stream_pcm_ack(&ff->domain, &ff->rx_stream);
 }

 int snd_ff_create_pcm_devices(struct snd_ff *ff)
 {
 	static const struct snd_pcm_ops pcm_capture_ops = {
 		.open		= pcm_open,
 		.close		= pcm_close,
 		.hw_params	= pcm_hw_params,
 		.hw_free	= pcm_hw_free,
 		.prepare	= pcm_capture_prepare,
 		.trigger	= pcm_capture_trigger,
 		.pointer	= pcm_capture_pointer,
 		.ack		= pcm_capture_ack,
 	};
 	static const struct snd_pcm_ops pcm_playback_ops = {
 		.open		= pcm_open,
 		.close		= pcm_close,
 		.hw_params	= pcm_hw_params,
 		.hw_free	= pcm_hw_free,
 		.prepare	= pcm_playback_prepare,
 		.trigger	= pcm_playback_trigger,
 		.pointer	= pcm_playback_pointer,
 		.ack		= pcm_playback_ack,
 	};
 	struct snd_pcm *pcm;
 	int err;

 	err = snd_pcm_new(ff->card, ff->card->driver, 0, 1, 1, &pcm);
 	if (err < 0)
 		return err;

 	pcm->private_data = ff;
 	pcm->nonatomic = true;
 	snprintf(pcm->name, sizeof(pcm->name),
 		 "%s PCM", ff->card->shortname);
 	snd_pcm_set_ops(pcm, SNDRV_PCM_STREAM_PLAYBACK, &pcm_playback_ops);
 	snd_pcm_set_ops(pcm, SNDRV_PCM_STREAM_CAPTURE, &pcm_capture_ops);
 	snd_pcm_set_managed_buffer_all(pcm, SNDRV_DMA_TYPE_VMALLOC, NULL, 0, 0);

 	return 0;
 }
	// SPDX-License-Identifier: GPL-2.0-only
	/*
	* ff-pcm.c - a part of driver for RME Fireface series
	*
	* Copyright (c) 2015-2017 Takashi Sakamoto
	*/

	#include "ff.h"

	static int hw_rule_rate(struct snd_pcm_hw_params *params,
	struct snd_pcm_hw_rule *rule)
	{
	const unsigned int *pcm_channels = rule->private;
	struct snd_interval *r =
	hw_param_interval(params, SNDRV_PCM_HW_PARAM_RATE);
	const struct snd_interval *c =
	hw_param_interval_c(params, SNDRV_PCM_HW_PARAM_CHANNELS);
	struct snd_interval t = {
	.min = UINT_MAX, .max = 0, .integer = 1
	};
	unsigned int i;

	for (i = 0; i < ARRAY_SIZE(amdtp_rate_table); i++) {
	enum snd_ff_stream_mode mode;
	int err;

	err = snd_ff_stream_get_multiplier_mode(i, &mode);
	if (err < 0)
	continue;

	if (!snd_interval_test(c, pcm_channels[mode]))
	continue;

	t.min = min(t.min, amdtp_rate_table[i]);
	t.max = max(t.max, amdtp_rate_table[i]);
	}

	return snd_interval_refine(r, &t);
	}

	static int hw_rule_channels(struct snd_pcm_hw_params *params,
	struct snd_pcm_hw_rule *rule)
	{
	const unsigned int *pcm_channels = rule->private;
	struct snd_interval *c =
	hw_param_interval(params, SNDRV_PCM_HW_PARAM_CHANNELS);
	const struct snd_interval *r =
	hw_param_interval_c(params, SNDRV_PCM_HW_PARAM_RATE);
	struct snd_interval t = {
	.min = UINT_MAX, .max = 0, .integer = 1
	};
	unsigned int i;

	for (i = 0; i < ARRAY_SIZE(amdtp_rate_table); i++) {
	enum snd_ff_stream_mode mode;
	int err;

	err = snd_ff_stream_get_multiplier_mode(i, &mode);
	if (err < 0)
	continue;

	if (!snd_interval_test(r, amdtp_rate_table[i]))
	continue;

	t.min = min(t.min, pcm_channels[mode]);
	t.max = max(t.max, pcm_channels[mode]);
	}

	return snd_interval_refine(c, &t);
	}

	static void limit_channels_and_rates(struct snd_pcm_hardware *hw,
	const unsigned int *pcm_channels)
	{
	unsigned int rate, channels;
	int i;

	hw->channels_min = UINT_MAX;
	hw->channels_max = 0;
	hw->rate_min = UINT_MAX;
	hw->rate_max = 0;

	for (i = 0; i < ARRAY_SIZE(amdtp_rate_table); i++) {
	enum snd_ff_stream_mode mode;
	int err;

	err = snd_ff_stream_get_multiplier_mode(i, &mode);
	if (err < 0)
	continue;

	channels = pcm_channels[mode];
	if (pcm_channels[mode] == 0)
	continue;
	hw->channels_min = min(hw->channels_min, channels);
	hw->channels_max = max(hw->channels_max, channels);

	rate = amdtp_rate_table[i];
	hw->rates \|= snd_pcm_rate_to_rate_bit(rate);
	hw->rate_min = min(hw->rate_min, rate);
	hw->rate_max = max(hw->rate_max, rate);
	}
	}

	static int pcm_init_hw_params(struct snd_ff *ff,
	struct snd_pcm_substream *substream)
	{
	struct snd_pcm_runtime *runtime = substream->runtime;
	struct amdtp_stream *s;
	const unsigned int *pcm_channels;
	int err;

	if (substream->stream == SNDRV_PCM_STREAM_CAPTURE) {
	runtime->hw.formats = SNDRV_PCM_FMTBIT_S32;
	s = &ff->tx_stream;
	pcm_channels = ff->spec->pcm_capture_channels;
	} else {
	runtime->hw.formats = SNDRV_PCM_FMTBIT_S32;
	s = &ff->rx_stream;
	pcm_channels = ff->spec->pcm_playback_channels;
	}

	limit_channels_and_rates(&runtime->hw, pcm_channels);

	err = snd_pcm_hw_rule_add(runtime, 0, SNDRV_PCM_HW_PARAM_CHANNELS,
	hw_rule_channels, (void *)pcm_channels,
	SNDRV_PCM_HW_PARAM_RATE, -1);
	if (err < 0)
	return err;

	err = snd_pcm_hw_rule_add(runtime, 0, SNDRV_PCM_HW_PARAM_RATE,
	hw_rule_rate, (void *)pcm_channels,
	SNDRV_PCM_HW_PARAM_CHANNELS, -1);
	if (err < 0)
	return err;

	return amdtp_ff_add_pcm_hw_constraints(s, runtime);
	}

	static int pcm_open(struct snd_pcm_substream *substream)
	{
	struct snd_ff *ff = substream->private_data;
	struct amdtp_domain *d = &ff->domain;
	unsigned int rate;
	enum snd_ff_clock_src src;
	int i, err;

	err = snd_ff_stream_lock_try(ff);
	if (err < 0)
	return err;

	err = pcm_init_hw_params(ff, substream);
	if (err < 0)
	goto release_lock;

	err = ff->spec->protocol->get_clock(ff, &rate, &src);
	if (err < 0)
	goto release_lock;

	mutex_lock(&ff->mutex);

	// When source of clock is not internal or any stream is reserved for
	// transmission of PCM frames, the available sampling rate is limited
	// at current one.
	if (src != SND_FF_CLOCK_SRC_INTERNAL) {
	for (i = 0; i < CIP_SFC_COUNT; ++i) {
	if (amdtp_rate_table[i] == rate)
	break;
	}

	// The unit is configured at sampling frequency which packet
	// streaming engine can't support.
	if (i >= CIP_SFC_COUNT) {
	mutex_unlock(&ff->mutex);
	err = -EIO;
	goto release_lock;
	}

	substream->runtime->hw.rate_min = rate;
	substream->runtime->hw.rate_max = rate;
	} else {
	if (ff->substreams_counter > 0) {
	unsigned int frames_per_period = d->events_per_period;
	unsigned int frames_per_buffer = d->events_per_buffer;

	rate = amdtp_rate_table[ff->rx_stream.sfc];
	substream->runtime->hw.rate_min = rate;
	substream->runtime->hw.rate_max = rate;

	err = snd_pcm_hw_constraint_minmax(substream->runtime,
	SNDRV_PCM_HW_PARAM_PERIOD_SIZE,
	frames_per_period, frames_per_period);
	if (err < 0) {
	mutex_unlock(&ff->mutex);
	goto release_lock;
	}

	err = snd_pcm_hw_constraint_minmax(substream->runtime,
	SNDRV_PCM_HW_PARAM_BUFFER_SIZE,
	frames_per_buffer, frames_per_buffer);
	if (err < 0) {
	mutex_unlock(&ff->mutex);
	goto release_lock;
	}
	}
	}

	mutex_unlock(&ff->mutex);

	snd_pcm_set_sync(substream);

	return 0;

	release_lock:
	snd_ff_stream_lock_release(ff);
	return err;
	}

	static int pcm_close(struct snd_pcm_substream *substream)
	{
	struct snd_ff *ff = substream->private_data;

	snd_ff_stream_lock_release(ff);

	return 0;
	}

	static int pcm_hw_params(struct snd_pcm_substream *substream,
	struct snd_pcm_hw_params *hw_params)
	{
	struct snd_ff *ff = substream->private_data;
	int err = 0;

	if (substream->runtime->state == SNDRV_PCM_STATE_OPEN) {
	unsigned int rate = params_rate(hw_params);
	unsigned int frames_per_period = params_period_size(hw_params);
	unsigned int frames_per_buffer = params_buffer_size(hw_params);

	mutex_lock(&ff->mutex);
	err = snd_ff_stream_reserve_duplex(ff, rate, frames_per_period,
	frames_per_buffer);
	if (err >= 0)
	++ff->substreams_counter;
	mutex_unlock(&ff->mutex);
	}

	return err;
	}

	static int pcm_hw_free(struct snd_pcm_substream *substream)
	{
	struct snd_ff *ff = substream->private_data;

	mutex_lock(&ff->mutex);

	if (substream->runtime->state != SNDRV_PCM_STATE_OPEN)
	--ff->substreams_counter;

	snd_ff_stream_stop_duplex(ff);

	mutex_unlock(&ff->mutex);

	return 0;
	}

	static int pcm_capture_prepare(struct snd_pcm_substream *substream)
	{
	struct snd_ff *ff = substream->private_data;
	struct snd_pcm_runtime *runtime = substream->runtime;
	int err;

	mutex_lock(&ff->mutex);

	err = snd_ff_stream_start_duplex(ff, runtime->rate);
	if (err >= 0)
	amdtp_stream_pcm_prepare(&ff->tx_stream);

	mutex_unlock(&ff->mutex);

	return err;
	}

	static int pcm_playback_prepare(struct snd_pcm_substream *substream)
	{
	struct snd_ff *ff = substream->private_data;
	struct snd_pcm_runtime *runtime = substream->runtime;
	int err;

	mutex_lock(&ff->mutex);

	err = snd_ff_stream_start_duplex(ff, runtime->rate);
	if (err >= 0)
	amdtp_stream_pcm_prepare(&ff->rx_stream);

	mutex_unlock(&ff->mutex);

	return err;
	}

	static int pcm_capture_trigger(struct snd_pcm_substream *substream, int cmd)
	{
	struct snd_ff *ff = substream->private_data;

	switch (cmd) {
	case SNDRV_PCM_TRIGGER_START:
	amdtp_stream_pcm_trigger(&ff->tx_stream, substream);
	break;
	case SNDRV_PCM_TRIGGER_STOP:
	amdtp_stream_pcm_trigger(&ff->tx_stream, NULL);
	break;
	default:
	return -EINVAL;
	}

	return 0;
	}

	static int pcm_playback_trigger(struct snd_pcm_substream *substream, int cmd)
	{
	struct snd_ff *ff = substream->private_data;

	switch (cmd) {
	case SNDRV_PCM_TRIGGER_START:
	amdtp_stream_pcm_trigger(&ff->rx_stream, substream);
	break;
	case SNDRV_PCM_TRIGGER_STOP:
	amdtp_stream_pcm_trigger(&ff->rx_stream, NULL);
	break;
	default:
	return -EINVAL;
	}

	return 0;
	}

	static snd_pcm_uframes_t pcm_capture_pointer(struct snd_pcm_substream *sbstrm)
	{
	struct snd_ff *ff = sbstrm->private_data;

	return amdtp_domain_stream_pcm_pointer(&ff->domain, &ff->tx_stream);
	}

	static snd_pcm_uframes_t pcm_playback_pointer(struct snd_pcm_substream *sbstrm)
	{
	struct snd_ff *ff = sbstrm->private_data;

	return amdtp_domain_stream_pcm_pointer(&ff->domain, &ff->rx_stream);
	}

	static int pcm_capture_ack(struct snd_pcm_substream *substream)
	{
	struct snd_ff *ff = substream->private_data;

	return amdtp_domain_stream_pcm_ack(&ff->domain, &ff->tx_stream);
	}

	static int pcm_playback_ack(struct snd_pcm_substream *substream)
	{
	struct snd_ff *ff = substream->private_data;

	return amdtp_domain_stream_pcm_ack(&ff->domain, &ff->rx_stream);
	}

	int snd_ff_create_pcm_devices(struct snd_ff *ff)
	{
	static const struct snd_pcm_ops pcm_capture_ops = {
	.open = pcm_open,
	.close = pcm_close,
	.hw_params = pcm_hw_params,
	.hw_free = pcm_hw_free,
	.prepare = pcm_capture_prepare,
	.trigger = pcm_capture_trigger,
	.pointer = pcm_capture_pointer,
	.ack = pcm_capture_ack,
	};
	static const struct snd_pcm_ops pcm_playback_ops = {
	.open = pcm_open,
	.close = pcm_close,
	.hw_params = pcm_hw_params,
	.hw_free = pcm_hw_free,
	.prepare = pcm_playback_prepare,
	.trigger = pcm_playback_trigger,
	.pointer = pcm_playback_pointer,
	.ack = pcm_playback_ack,
	};
	struct snd_pcm *pcm;
	int err;

	err = snd_pcm_new(ff->card, ff->card->driver, 0, 1, 1, &pcm);
	if (err < 0)
	return err;

	pcm->private_data = ff;
	pcm->nonatomic = true;
	snprintf(pcm->name, sizeof(pcm->name),
	"%s PCM", ff->card->shortname);
	snd_pcm_set_ops(pcm, SNDRV_PCM_STREAM_PLAYBACK, &pcm_playback_ops);
	snd_pcm_set_ops(pcm, SNDRV_PCM_STREAM_CAPTURE, &pcm_capture_ops);
	snd_pcm_set_managed_buffer_all(pcm, SNDRV_DMA_TYPE_VMALLOC, NULL, 0, 0);

	return 0;
	}