drivers/staging/line6/playback.c - kernel/skids - Git at Google

 /*
  * Line6 Linux USB driver - 0.8.0
  *
  * Copyright (C) 2004-2009 Markus Grabner (grabner@icg.tugraz.at)
  *
  *	This program is free software; you can redistribute it and/or
  *	modify it under the terms of the GNU General Public License as
  *	published by the Free Software Foundation, version 2.
  *
  */

 #include "driver.h"

 #include <linux/slab.h>

 #include <sound/core.h>
 #include <sound/pcm.h>
 #include <sound/pcm_params.h>

 #include "audio.h"
 #include "pcm.h"
 #include "pod.h"
 #include "playback.h"

 /*
 	Software stereo volume control.
 */
 static void change_volume(struct urb *urb_out, int volume[],
 			  int bytes_per_frame)
 {
 	int chn = 0;

 	if (volume[0] == 256 && volume[1] == 256)
 		return;		/* maximum volume - no change */

 	if (bytes_per_frame == 4) {
 		short *p, *buf_end;
 		p = (short *)urb_out->transfer_buffer;
 		buf_end = p + urb_out->transfer_buffer_length / sizeof(*p);

 		for (; p < buf_end; ++p) {
 			*p = (*p * volume[chn & 1]) >> 8;
 			++chn;
 		}
 	} else if (bytes_per_frame == 6) {
 		unsigned char *p, *buf_end;
 		p = (unsigned char *)urb_out->transfer_buffer;
 		buf_end = p + urb_out->transfer_buffer_length;

 		for (; p < buf_end; p += 3) {
 			int val;
 			val = p[0] + (p[1] << 8) + ((signed char)p[2] << 16);
 			val = (val * volume[chn & 1]) >> 8;
 			p[0] = val;
 			p[1] = val >> 8;
 			p[2] = val >> 16;
 			++chn;
 		}
 	}
 }

 /*
 	Find a free URB, prepare audio data, and submit URB.
 */
 static int submit_audio_out_urb(struct snd_pcm_substream *substream)
 {
 	int index;
 	unsigned long flags;
 	int i, urb_size, urb_frames;
 	struct snd_line6_pcm *line6pcm = snd_pcm_substream_chip(substream);
 	const int bytes_per_frame = line6pcm->properties->bytes_per_frame;
 	const int frame_increment =
 	    line6pcm->properties->snd_line6_rates.rats[0].num_min;
 	const int frame_factor =
 	    line6pcm->properties->snd_line6_rates.rats[0].den *
 	    (USB_INTERVALS_PER_SECOND / LINE6_ISO_INTERVAL);
 	struct snd_pcm_runtime *runtime = substream->runtime;
 	struct urb *urb_out;

 	spin_lock_irqsave(&line6pcm->lock_audio_out, flags);
 	index =
 	    find_first_zero_bit(&line6pcm->active_urb_out, LINE6_ISO_BUFFERS);

 	if (index < 0 || index >= LINE6_ISO_BUFFERS) {
 		spin_unlock_irqrestore(&line6pcm->lock_audio_out, flags);
 		dev_err(s2m(substream), "no free URB found\n");
 		return -EINVAL;
 	}

 	urb_out = line6pcm->urb_audio_out[index];
 	urb_size = 0;

 	for (i = 0; i < LINE6_ISO_PACKETS; ++i) {
 		/* compute frame size for given sampling rate */
 		int n, fs;
 		struct usb_iso_packet_descriptor *fout =
 		    &urb_out->iso_frame_desc[i];
 		line6pcm->count_out += frame_increment;
 		n = line6pcm->count_out / frame_factor;
 		line6pcm->count_out -= n * frame_factor;
 		fs = n * bytes_per_frame;
 		fout->offset = urb_size;
 		fout->length = fs;
 		urb_size += fs;
 	}

 	urb_frames = urb_size / bytes_per_frame;

 	if (test_bit(BIT_PAUSE_PLAYBACK, &line6pcm->flags)) {
 		urb_out->transfer_buffer = line6pcm->wrap_out;
 		memset(line6pcm->wrap_out, 0, urb_size);
 	} else {
 		if (line6pcm->pos_out + urb_frames > runtime->buffer_size) {
 			/*
 			   The transferred area goes over buffer boundary,
 			   copy the data to the temp buffer.
 			 */
 			int len;
 			len = runtime->buffer_size - line6pcm->pos_out;
 			urb_out->transfer_buffer = line6pcm->wrap_out;

 			if (len > 0) {
 				memcpy(line6pcm->wrap_out,
 				       runtime->dma_area +
 				       line6pcm->pos_out * bytes_per_frame,
 				       len * bytes_per_frame);
 				memcpy(line6pcm->wrap_out +
 				       len * bytes_per_frame, runtime->dma_area,
 				       (urb_frames - len) * bytes_per_frame);
 			} else {
 				/* this is somewhat paranoid */
 				dev_err(s2m(substream),
 					"driver bug: len = %d\n", len);
 			}
 		} else {
 			/* set the buffer pointer */
 			urb_out->transfer_buffer =
 			    runtime->dma_area +
 			    line6pcm->pos_out * bytes_per_frame;
 		}
 	}

 	line6pcm->pos_out += urb_frames;
 	if (line6pcm->pos_out >= runtime->buffer_size)
 		line6pcm->pos_out -= runtime->buffer_size;

 	urb_out->transfer_buffer_length = urb_size;
 	urb_out->context = substream;
 	change_volume(urb_out, line6pcm->volume, bytes_per_frame);

 #if DO_DUMP_PCM_SEND
 	for (i = 0; i < LINE6_ISO_PACKETS; ++i) {
 		struct usb_iso_packet_descriptor *fout =
 		    &urb_out->iso_frame_desc[i];
 		line6_write_hexdump(line6pcm->line6, 'P',
 				    urb_out->transfer_buffer + fout->offset,
 				    fout->length);
 	}
 #endif

 	if (usb_submit_urb(urb_out, GFP_ATOMIC) == 0)
 		set_bit(index, &line6pcm->active_urb_out);
 	else
 		dev_err(s2m(substream), "URB out #%d submission failed\n",
 			index);

 	spin_unlock_irqrestore(&line6pcm->lock_audio_out, flags);
 	return 0;
 }

 /*
 	Submit all currently available playback URBs.
 */
 static int submit_audio_out_all_urbs(struct snd_pcm_substream *substream)
 {
 	int ret, i;

 	for (i = 0; i < LINE6_ISO_BUFFERS; ++i) {
 		ret = submit_audio_out_urb(substream);
 		if (ret < 0)
 			return ret;
 	}

 	return 0;
 }

 /*
 	Unlink all currently active playback URBs.
 */
 static void unlink_audio_out_urbs(struct snd_line6_pcm *line6pcm)
 {
 	unsigned int i;

 	for (i = LINE6_ISO_BUFFERS; i--;) {
 		if (test_bit(i, &line6pcm->active_urb_out)) {
 			if (!test_and_set_bit(i, &line6pcm->unlink_urb_out)) {
 				struct urb *u = line6pcm->urb_audio_out[i];
 				usb_unlink_urb(u);
 			}
 		}
 	}
 }

 /*
    Wait until unlinking of all currently active playback URBs has been finished.
 */
 static void wait_clear_audio_out_urbs(struct snd_line6_pcm *line6pcm)
 {
 	int timeout = HZ;
 	unsigned int i;
 	int alive;

 	do {
 		alive = 0;
 		for (i = LINE6_ISO_BUFFERS; i--;) {
 			if (test_bit(i, &line6pcm->active_urb_out))
 				alive++;
 		}
 		if (!alive)
 			break;
 		set_current_state(TASK_UNINTERRUPTIBLE);
 		schedule_timeout(1);
 	} while (--timeout > 0);
 	if (alive)
 		snd_printk(KERN_ERR "timeout: still %d active urbs..\n", alive);

 	line6pcm->active_urb_out = 0;
 	line6pcm->unlink_urb_out = 0;
 }

 /*
 	Unlink all currently active playback URBs, and wait for finishing.
 */
 void unlink_wait_clear_audio_out_urbs(struct snd_line6_pcm *line6pcm)
 {
 	unlink_audio_out_urbs(line6pcm);
 	wait_clear_audio_out_urbs(line6pcm);
 }

 /*
 	Callback for completed playback URB.
 */
 static void audio_out_callback(struct urb *urb)
 {
 	int i, index, length = 0, shutdown = 0;
 	unsigned long flags;

 	struct snd_pcm_substream *substream =
 	    (struct snd_pcm_substream *)urb->context;
 	struct snd_line6_pcm *line6pcm = snd_pcm_substream_chip(substream);
 	struct snd_pcm_runtime *runtime = substream->runtime;

 	/* find index of URB */
 	for (index = LINE6_ISO_BUFFERS; index--;)
 		if (urb == line6pcm->urb_audio_out[index])
 			break;

 	if (index < 0)
 		return;		/* URB has been unlinked asynchronously */

 	for (i = LINE6_ISO_PACKETS; i--;)
 		length += urb->iso_frame_desc[i].length;

 	spin_lock_irqsave(&line6pcm->lock_audio_out, flags);
 	line6pcm->pos_out_done +=
 	    length / line6pcm->properties->bytes_per_frame;

 	if (line6pcm->pos_out_done >= runtime->buffer_size)
 		line6pcm->pos_out_done -= runtime->buffer_size;

 	clear_bit(index, &line6pcm->active_urb_out);

 	for (i = LINE6_ISO_PACKETS; i--;)
 		if (urb->iso_frame_desc[i].status == -ESHUTDOWN) {
 			shutdown = 1;
 			break;
 		}

 	if (test_bit(index, &line6pcm->unlink_urb_out))
 		shutdown = 1;

 	spin_unlock_irqrestore(&line6pcm->lock_audio_out, flags);

 	if (!shutdown) {
 		submit_audio_out_urb(substream);

 		line6pcm->bytes_out += length;
 		if (line6pcm->bytes_out >= line6pcm->period_out) {
 			line6pcm->bytes_out -= line6pcm->period_out;
 			snd_pcm_period_elapsed(substream);
 		}
 	}
 }

 /* open playback callback */
 static int snd_line6_playback_open(struct snd_pcm_substream *substream)
 {
 	int err;
 	struct snd_pcm_runtime *runtime = substream->runtime;
 	struct snd_line6_pcm *line6pcm = snd_pcm_substream_chip(substream);

 	err = snd_pcm_hw_constraint_ratdens(runtime, 0, SNDRV_PCM_HW_PARAM_RATE,
 					    (&line6pcm->properties->
 					     snd_line6_rates));
 	if (err < 0)
 		return err;

 	runtime->hw = line6pcm->properties->snd_line6_playback_hw;
 	return 0;
 }

 /* close playback callback */
 static int snd_line6_playback_close(struct snd_pcm_substream *substream)
 {
 	return 0;
 }

 /* hw_params playback callback */
 static int snd_line6_playback_hw_params(struct snd_pcm_substream *substream,
 					struct snd_pcm_hw_params *hw_params)
 {
 	int ret;
 	struct snd_line6_pcm *line6pcm = snd_pcm_substream_chip(substream);

 	/* -- Florian Demski [FD] */
 	/* don't ask me why, but this fixes the bug on my machine */
 	if (line6pcm == NULL) {
 		if (substream->pcm == NULL)
 			return -ENOMEM;
 		if (substream->pcm->private_data == NULL)
 			return -ENOMEM;
 		substream->private_data = substream->pcm->private_data;
 		line6pcm = snd_pcm_substream_chip(substream);
 	}
 	/* -- [FD] end */

 	ret = snd_pcm_lib_malloc_pages(substream,
 				       params_buffer_bytes(hw_params));
 	if (ret < 0)
 		return ret;

 	line6pcm->period_out = params_period_bytes(hw_params);
 	line6pcm->wrap_out = kmalloc(2 * LINE6_ISO_PACKET_SIZE_MAX, GFP_KERNEL);

 	if (!line6pcm->wrap_out) {
 		dev_err(s2m(substream), "cannot malloc wrap_out\n");
 		return -ENOMEM;
 	}

 	return 0;
 }

 /* hw_free playback callback */
 static int snd_line6_playback_hw_free(struct snd_pcm_substream *substream)
 {
 	struct snd_line6_pcm *line6pcm = snd_pcm_substream_chip(substream);
 	unlink_wait_clear_audio_out_urbs(line6pcm);

 	kfree(line6pcm->wrap_out);
 	line6pcm->wrap_out = NULL;

 	return snd_pcm_lib_free_pages(substream);
 }

 /* trigger playback callback */
 int snd_line6_playback_trigger(struct snd_pcm_substream *substream, int cmd)
 {
 	struct snd_line6_pcm *line6pcm = snd_pcm_substream_chip(substream);
 	int err;
 	line6pcm->count_out = 0;

 	switch (cmd) {
 	case SNDRV_PCM_TRIGGER_START:
 		if (!test_and_set_bit(BIT_RUNNING_PLAYBACK, &line6pcm->flags)) {
 			err = submit_audio_out_all_urbs(substream);

 			if (err < 0) {
 				clear_bit(BIT_RUNNING_PLAYBACK,
 					  &line6pcm->flags);
 				return err;
 			}
 		}

 		break;

 	case SNDRV_PCM_TRIGGER_STOP:
 		if (test_and_clear_bit(BIT_RUNNING_PLAYBACK, &line6pcm->flags))
 			unlink_audio_out_urbs(line6pcm);

 		break;

 	case SNDRV_PCM_TRIGGER_PAUSE_PUSH:
 		set_bit(BIT_PAUSE_PLAYBACK, &line6pcm->flags);
 		break;

 	case SNDRV_PCM_TRIGGER_PAUSE_RELEASE:
 		clear_bit(BIT_PAUSE_PLAYBACK, &line6pcm->flags);
 		break;

 	default:
 		return -EINVAL;
 	}

 	return 0;
 }

 /* playback pointer callback */
 static snd_pcm_uframes_t
 snd_line6_playback_pointer(struct snd_pcm_substream *substream)
 {
 	struct snd_line6_pcm *line6pcm = snd_pcm_substream_chip(substream);
 	return line6pcm->pos_out_done;
 }

 /* playback operators */
 struct snd_pcm_ops snd_line6_playback_ops = {
 	.open = snd_line6_playback_open,
 	.close = snd_line6_playback_close,
 	.ioctl = snd_pcm_lib_ioctl,
 	.hw_params = snd_line6_playback_hw_params,
 	.hw_free = snd_line6_playback_hw_free,
 	.prepare = snd_line6_prepare,
 	.trigger = snd_line6_trigger,
 	.pointer = snd_line6_playback_pointer,
 };

 int create_audio_out_urbs(struct snd_line6_pcm *line6pcm)
 {
 	int i;

 	/* create audio URBs and fill in constant values: */
 	for (i = 0; i < LINE6_ISO_BUFFERS; ++i) {
 		struct urb *urb;

 		/* URB for audio out: */
 		urb = line6pcm->urb_audio_out[i] =
 		    usb_alloc_urb(LINE6_ISO_PACKETS, GFP_KERNEL);

 		if (urb == NULL) {
 			dev_err(line6pcm->line6->ifcdev, "Out of memory\n");
 			return -ENOMEM;
 		}

 		urb->dev = line6pcm->line6->usbdev;
 		urb->pipe =
 		    usb_sndisocpipe(line6pcm->line6->usbdev,
 				    line6pcm->
 				    ep_audio_write & USB_ENDPOINT_NUMBER_MASK);
 		urb->transfer_flags = URB_ISO_ASAP;
 		urb->start_frame = -1;
 		urb->number_of_packets = LINE6_ISO_PACKETS;
 		urb->interval = LINE6_ISO_INTERVAL;
 		urb->error_count = 0;
 		urb->complete = audio_out_callback;
 	}

 	return 0;
 }
	/*
	* Line6 Linux USB driver - 0.8.0
	*
	* Copyright (C) 2004-2009 Markus Grabner (grabner@icg.tugraz.at)
	*
	* This program is free software; you can redistribute it and/or
	* modify it under the terms of the GNU General Public License as
	* published by the Free Software Foundation, version 2.
	*
	*/

	#include "driver.h"

	#include <linux/slab.h>

	#include <sound/core.h>
	#include <sound/pcm.h>
	#include <sound/pcm_params.h>

	#include "audio.h"
	#include "pcm.h"
	#include "pod.h"
	#include "playback.h"

	/*
	Software stereo volume control.
	*/
	static void change_volume(struct urb *urb_out, int volume[],
	int bytes_per_frame)
	{
	int chn = 0;

	if (volume[0] == 256 && volume[1] == 256)
	return; /* maximum volume - no change */

	if (bytes_per_frame == 4) {
	short p, buf_end;
	p = (short *)urb_out->transfer_buffer;
	buf_end = p + urb_out->transfer_buffer_length / sizeof(*p);

	for (; p < buf_end; ++p) {
	p = (p * volume[chn & 1]) >> 8;
	++chn;
	}
	} else if (bytes_per_frame == 6) {
	unsigned char p, buf_end;
	p = (unsigned char *)urb_out->transfer_buffer;
	buf_end = p + urb_out->transfer_buffer_length;

	for (; p < buf_end; p += 3) {
	int val;
	val = p[0] + (p[1] << 8) + ((signed char)p[2] << 16);
	val = (val * volume[chn & 1]) >> 8;
	p[0] = val;
	p[1] = val >> 8;
	p[2] = val >> 16;
	++chn;
	}
	}
	}

	/*
	Find a free URB, prepare audio data, and submit URB.
	*/
	static int submit_audio_out_urb(struct snd_pcm_substream *substream)
	{
	int index;
	unsigned long flags;
	int i, urb_size, urb_frames;
	struct snd_line6_pcm *line6pcm = snd_pcm_substream_chip(substream);
	const int bytes_per_frame = line6pcm->properties->bytes_per_frame;
	const int frame_increment =
	line6pcm->properties->snd_line6_rates.rats[0].num_min;
	const int frame_factor =
	line6pcm->properties->snd_line6_rates.rats[0].den *
	(USB_INTERVALS_PER_SECOND / LINE6_ISO_INTERVAL);
	struct snd_pcm_runtime *runtime = substream->runtime;
	struct urb *urb_out;

	spin_lock_irqsave(&line6pcm->lock_audio_out, flags);
	index =
	find_first_zero_bit(&line6pcm->active_urb_out, LINE6_ISO_BUFFERS);

	if (index < 0 \|\| index >= LINE6_ISO_BUFFERS) {
	spin_unlock_irqrestore(&line6pcm->lock_audio_out, flags);
	dev_err(s2m(substream), "no free URB found\n");
	return -EINVAL;
	}

	urb_out = line6pcm->urb_audio_out[index];
	urb_size = 0;

	for (i = 0; i < LINE6_ISO_PACKETS; ++i) {
	/* compute frame size for given sampling rate */
	int n, fs;
	struct usb_iso_packet_descriptor *fout =
	&urb_out->iso_frame_desc[i];
	line6pcm->count_out += frame_increment;
	n = line6pcm->count_out / frame_factor;
	line6pcm->count_out -= n * frame_factor;
	fs = n * bytes_per_frame;
	fout->offset = urb_size;
	fout->length = fs;
	urb_size += fs;
	}

	urb_frames = urb_size / bytes_per_frame;

	if (test_bit(BIT_PAUSE_PLAYBACK, &line6pcm->flags)) {
	urb_out->transfer_buffer = line6pcm->wrap_out;
	memset(line6pcm->wrap_out, 0, urb_size);
	} else {
	if (line6pcm->pos_out + urb_frames > runtime->buffer_size) {
	/*
	The transferred area goes over buffer boundary,
	copy the data to the temp buffer.
	*/
	int len;
	len = runtime->buffer_size - line6pcm->pos_out;
	urb_out->transfer_buffer = line6pcm->wrap_out;

	if (len > 0) {
	memcpy(line6pcm->wrap_out,
	runtime->dma_area +
	line6pcm->pos_out * bytes_per_frame,
	len * bytes_per_frame);
	memcpy(line6pcm->wrap_out +
	len * bytes_per_frame, runtime->dma_area,
	(urb_frames - len) * bytes_per_frame);
	} else {
	/* this is somewhat paranoid */
	dev_err(s2m(substream),
	"driver bug: len = %d\n", len);
	}
	} else {
	/* set the buffer pointer */
	urb_out->transfer_buffer =
	runtime->dma_area +
	line6pcm->pos_out * bytes_per_frame;
	}
	}

	line6pcm->pos_out += urb_frames;
	if (line6pcm->pos_out >= runtime->buffer_size)
	line6pcm->pos_out -= runtime->buffer_size;

	urb_out->transfer_buffer_length = urb_size;
	urb_out->context = substream;
	change_volume(urb_out, line6pcm->volume, bytes_per_frame);

	#if DO_DUMP_PCM_SEND
	for (i = 0; i < LINE6_ISO_PACKETS; ++i) {
	struct usb_iso_packet_descriptor *fout =
	&urb_out->iso_frame_desc[i];
	line6_write_hexdump(line6pcm->line6, 'P',
	urb_out->transfer_buffer + fout->offset,
	fout->length);
	}
	#endif

	if (usb_submit_urb(urb_out, GFP_ATOMIC) == 0)
	set_bit(index, &line6pcm->active_urb_out);
	else
	dev_err(s2m(substream), "URB out #%d submission failed\n",
	index);

	spin_unlock_irqrestore(&line6pcm->lock_audio_out, flags);
	return 0;
	}

	/*
	Submit all currently available playback URBs.
	*/
	static int submit_audio_out_all_urbs(struct snd_pcm_substream *substream)
	{
	int ret, i;

	for (i = 0; i < LINE6_ISO_BUFFERS; ++i) {
	ret = submit_audio_out_urb(substream);
	if (ret < 0)
	return ret;
	}

	return 0;
	}

	/*
	Unlink all currently active playback URBs.
	*/
	static void unlink_audio_out_urbs(struct snd_line6_pcm *line6pcm)
	{
	unsigned int i;

	for (i = LINE6_ISO_BUFFERS; i--;) {
	if (test_bit(i, &line6pcm->active_urb_out)) {
	if (!test_and_set_bit(i, &line6pcm->unlink_urb_out)) {
	struct urb *u = line6pcm->urb_audio_out[i];
	usb_unlink_urb(u);
	}
	}
	}
	}

	/*
	Wait until unlinking of all currently active playback URBs has been finished.
	*/
	static void wait_clear_audio_out_urbs(struct snd_line6_pcm *line6pcm)
	{
	int timeout = HZ;
	unsigned int i;
	int alive;

	do {
	alive = 0;
	for (i = LINE6_ISO_BUFFERS; i--;) {
	if (test_bit(i, &line6pcm->active_urb_out))
	alive++;
	}
	if (!alive)
	break;
	set_current_state(TASK_UNINTERRUPTIBLE);
	schedule_timeout(1);
	} while (--timeout > 0);
	if (alive)
	snd_printk(KERN_ERR "timeout: still %d active urbs..\n", alive);

	line6pcm->active_urb_out = 0;
	line6pcm->unlink_urb_out = 0;
	}

	/*
	Unlink all currently active playback URBs, and wait for finishing.
	*/
	void unlink_wait_clear_audio_out_urbs(struct snd_line6_pcm *line6pcm)
	{
	unlink_audio_out_urbs(line6pcm);
	wait_clear_audio_out_urbs(line6pcm);
	}

	/*
	Callback for completed playback URB.
	*/
	static void audio_out_callback(struct urb *urb)
	{
	int i, index, length = 0, shutdown = 0;
	unsigned long flags;

	struct snd_pcm_substream *substream =
	(struct snd_pcm_substream *)urb->context;
	struct snd_line6_pcm *line6pcm = snd_pcm_substream_chip(substream);
	struct snd_pcm_runtime *runtime = substream->runtime;

	/* find index of URB */
	for (index = LINE6_ISO_BUFFERS; index--;)
	if (urb == line6pcm->urb_audio_out[index])
	break;

	if (index < 0)
	return; /* URB has been unlinked asynchronously */

	for (i = LINE6_ISO_PACKETS; i--;)
	length += urb->iso_frame_desc[i].length;

	spin_lock_irqsave(&line6pcm->lock_audio_out, flags);
	line6pcm->pos_out_done +=
	length / line6pcm->properties->bytes_per_frame;

	if (line6pcm->pos_out_done >= runtime->buffer_size)
	line6pcm->pos_out_done -= runtime->buffer_size;

	clear_bit(index, &line6pcm->active_urb_out);

	for (i = LINE6_ISO_PACKETS; i--;)
	if (urb->iso_frame_desc[i].status == -ESHUTDOWN) {
	shutdown = 1;
	break;
	}

	if (test_bit(index, &line6pcm->unlink_urb_out))
	shutdown = 1;

	spin_unlock_irqrestore(&line6pcm->lock_audio_out, flags);

	if (!shutdown) {
	submit_audio_out_urb(substream);

	line6pcm->bytes_out += length;
	if (line6pcm->bytes_out >= line6pcm->period_out) {
	line6pcm->bytes_out -= line6pcm->period_out;
	snd_pcm_period_elapsed(substream);
	}
	}
	}

	/* open playback callback */
	static int snd_line6_playback_open(struct snd_pcm_substream *substream)
	{
	int err;
	struct snd_pcm_runtime *runtime = substream->runtime;
	struct snd_line6_pcm *line6pcm = snd_pcm_substream_chip(substream);

	err = snd_pcm_hw_constraint_ratdens(runtime, 0, SNDRV_PCM_HW_PARAM_RATE,
	(&line6pcm->properties->
	snd_line6_rates));
	if (err < 0)
	return err;

	runtime->hw = line6pcm->properties->snd_line6_playback_hw;
	return 0;
	}

	/* close playback callback */
	static int snd_line6_playback_close(struct snd_pcm_substream *substream)
	{
	return 0;
	}

	/* hw_params playback callback */
	static int snd_line6_playback_hw_params(struct snd_pcm_substream *substream,
	struct snd_pcm_hw_params *hw_params)
	{
	int ret;
	struct snd_line6_pcm *line6pcm = snd_pcm_substream_chip(substream);

	/* -- Florian Demski [FD] */
	/* don't ask me why, but this fixes the bug on my machine */
	if (line6pcm == NULL) {
	if (substream->pcm == NULL)
	return -ENOMEM;
	if (substream->pcm->private_data == NULL)
	return -ENOMEM;
	substream->private_data = substream->pcm->private_data;
	line6pcm = snd_pcm_substream_chip(substream);
	}
	/* -- [FD] end */

	ret = snd_pcm_lib_malloc_pages(substream,
	params_buffer_bytes(hw_params));
	if (ret < 0)
	return ret;

	line6pcm->period_out = params_period_bytes(hw_params);
	line6pcm->wrap_out = kmalloc(2 * LINE6_ISO_PACKET_SIZE_MAX, GFP_KERNEL);

	if (!line6pcm->wrap_out) {
	dev_err(s2m(substream), "cannot malloc wrap_out\n");
	return -ENOMEM;
	}

	return 0;
	}

	/* hw_free playback callback */
	static int snd_line6_playback_hw_free(struct snd_pcm_substream *substream)
	{
	struct snd_line6_pcm *line6pcm = snd_pcm_substream_chip(substream);
	unlink_wait_clear_audio_out_urbs(line6pcm);

	kfree(line6pcm->wrap_out);
	line6pcm->wrap_out = NULL;

	return snd_pcm_lib_free_pages(substream);
	}

	/* trigger playback callback */
	int snd_line6_playback_trigger(struct snd_pcm_substream *substream, int cmd)
	{
	struct snd_line6_pcm *line6pcm = snd_pcm_substream_chip(substream);
	int err;
	line6pcm->count_out = 0;

	switch (cmd) {
	case SNDRV_PCM_TRIGGER_START:
	if (!test_and_set_bit(BIT_RUNNING_PLAYBACK, &line6pcm->flags)) {
	err = submit_audio_out_all_urbs(substream);

	if (err < 0) {
	clear_bit(BIT_RUNNING_PLAYBACK,
	&line6pcm->flags);
	return err;
	}
	}

	break;

	case SNDRV_PCM_TRIGGER_STOP:
	if (test_and_clear_bit(BIT_RUNNING_PLAYBACK, &line6pcm->flags))
	unlink_audio_out_urbs(line6pcm);

	break;

	case SNDRV_PCM_TRIGGER_PAUSE_PUSH:
	set_bit(BIT_PAUSE_PLAYBACK, &line6pcm->flags);
	break;

	case SNDRV_PCM_TRIGGER_PAUSE_RELEASE:
	clear_bit(BIT_PAUSE_PLAYBACK, &line6pcm->flags);
	break;

	default:
	return -EINVAL;
	}

	return 0;
	}

	/* playback pointer callback */
	static snd_pcm_uframes_t
	snd_line6_playback_pointer(struct snd_pcm_substream *substream)
	{
	struct snd_line6_pcm *line6pcm = snd_pcm_substream_chip(substream);
	return line6pcm->pos_out_done;
	}

	/* playback operators */
	struct snd_pcm_ops snd_line6_playback_ops = {
	.open = snd_line6_playback_open,
	.close = snd_line6_playback_close,
	.ioctl = snd_pcm_lib_ioctl,
	.hw_params = snd_line6_playback_hw_params,
	.hw_free = snd_line6_playback_hw_free,
	.prepare = snd_line6_prepare,
	.trigger = snd_line6_trigger,
	.pointer = snd_line6_playback_pointer,
	};

	int create_audio_out_urbs(struct snd_line6_pcm *line6pcm)
	{
	int i;

	/* create audio URBs and fill in constant values: */
	for (i = 0; i < LINE6_ISO_BUFFERS; ++i) {
	struct urb *urb;

	/* URB for audio out: */
	urb = line6pcm->urb_audio_out[i] =
	usb_alloc_urb(LINE6_ISO_PACKETS, GFP_KERNEL);

	if (urb == NULL) {
	dev_err(line6pcm->line6->ifcdev, "Out of memory\n");
	return -ENOMEM;
	}

	urb->dev = line6pcm->line6->usbdev;
	urb->pipe =
	usb_sndisocpipe(line6pcm->line6->usbdev,
	line6pcm->
	ep_audio_write & USB_ENDPOINT_NUMBER_MASK);
	urb->transfer_flags = URB_ISO_ASAP;
	urb->start_frame = -1;
	urb->number_of_packets = LINE6_ISO_PACKETS;
	urb->interval = LINE6_ISO_INTERVAL;
	urb->error_count = 0;
	urb->complete = audio_out_callback;
	}

	return 0;
	}