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linux/sound/soc/samsung/dma.c
Tomasz Figa 9b9ae16a97 ASoC: Samsung: Do not queue cyclic buffers multiple times 
The legacy S3C-DMA API required every period of a cyclic buffer to be
queued separately. After conversion of Samsung ASoC to Samsung DMA
wrappers somebody made an assumption that the same is needed for DMA
engine API, which is not true.

In effect, Samsung ASoC DMA code was queuing the whole cyclic buffer
multiple times with a shift of one period per iteration, leading to:
  a) severe memory waste - up to 13x times more DMA transfer descriptors
     are allocated than needed,
  b) possible memory corruption, because further cyclic buffers were out
     of the original buffers, due to the offset.

This patch fixes this problem by making the legacy S3C-DMA API use the
same semantics as DMA engine (the whole cyclic buffer is enqueued at
once) and modifying users of Samsung DMA wrappers in cyclic mode to
behave appropriately.

Signed-off-by: Tomasz Figa <tomasz.figa@gmail.com>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Mark Brown <broonie@linaro.org>
2013-08-29 17:31:02 +01:00

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/*
* dma.c -- ALSA Soc Audio Layer
*
* (c) 2006 Wolfson Microelectronics PLC.
* Graeme Gregory graeme.gregory@wolfsonmicro.com or linux@wolfsonmicro.com
*
* Copyright 2004-2005 Simtec Electronics
* http://armlinux.simtec.co.uk/
* Ben Dooks <ben@simtec.co.uk>
*
* 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; either version 2 of the License, or (at your
* option) any later version.
*/
#include <linux/slab.h>
#include <linux/dma-mapping.h>
#include <linux/module.h>
#include <sound/soc.h>
#include <sound/pcm_params.h>
#include <asm/dma.h>
#include <mach/hardware.h>
#include <mach/dma.h>
#include "dma.h"
#define ST_RUNNING (1<<0)
#define ST_OPENED (1<<1)
static const struct snd_pcm_hardware dma_hardware = {
.info = SNDRV_PCM_INFO_INTERLEAVED |
SNDRV_PCM_INFO_BLOCK_TRANSFER |
SNDRV_PCM_INFO_MMAP |
SNDRV_PCM_INFO_MMAP_VALID,
.formats = SNDRV_PCM_FMTBIT_S16_LE |
SNDRV_PCM_FMTBIT_U16_LE |
SNDRV_PCM_FMTBIT_U8 |
SNDRV_PCM_FMTBIT_S8,
.channels_min = 2,
.channels_max = 2,
.buffer_bytes_max = 128*1024,
.period_bytes_min = PAGE_SIZE,
.period_bytes_max = PAGE_SIZE*2,
.periods_min = 2,
.periods_max = 128,
.fifo_size = 32,
};
struct runtime_data {
spinlock_t lock;
int state;
unsigned int dma_loaded;
unsigned int dma_period;
dma_addr_t dma_start;
dma_addr_t dma_pos;
dma_addr_t dma_end;
struct s3c_dma_params *params;
};
static void audio_buffdone(void *data);
/* dma_enqueue
*
* place a dma buffer onto the queue for the dma system
* to handle.
*/
static void dma_enqueue(struct snd_pcm_substream *substream)
{
struct runtime_data *prtd = substream->runtime->private_data;
dma_addr_t pos = prtd->dma_pos;
unsigned int limit;
struct samsung_dma_prep dma_info;
pr_debug("Entered %s\n", __func__);
limit = (prtd->dma_end - prtd->dma_start) / prtd->dma_period;
pr_debug("%s: loaded %d, limit %d\n",
__func__, prtd->dma_loaded, limit);
dma_info.cap = (samsung_dma_has_circular() ? DMA_CYCLIC : DMA_SLAVE);
dma_info.direction =
(substream->stream == SNDRV_PCM_STREAM_PLAYBACK
? DMA_MEM_TO_DEV : DMA_DEV_TO_MEM);
dma_info.fp = audio_buffdone;
dma_info.fp_param = substream;
dma_info.period = prtd->dma_period;
dma_info.len = prtd->dma_period*limit;
if (dma_info.cap == DMA_CYCLIC) {
dma_info.buf = pos;
prtd->params->ops->prepare(prtd->params->ch, &dma_info);
prtd->dma_loaded += limit;
return;
}
while (prtd->dma_loaded < limit) {
pr_debug("dma_loaded: %d\n", prtd->dma_loaded);
if ((pos + dma_info.period) > prtd->dma_end) {
dma_info.period = prtd->dma_end - pos;
pr_debug("%s: corrected dma len %ld\n",
__func__, dma_info.period);
}
dma_info.buf = pos;
prtd->params->ops->prepare(prtd->params->ch, &dma_info);
prtd->dma_loaded++;
pos += prtd->dma_period;
if (pos >= prtd->dma_end)
pos = prtd->dma_start;
}
prtd->dma_pos = pos;
}
static void audio_buffdone(void *data)
{
struct snd_pcm_substream *substream = data;
struct runtime_data *prtd = substream->runtime->private_data;
pr_debug("Entered %s\n", __func__);
if (prtd->state & ST_RUNNING) {
prtd->dma_pos += prtd->dma_period;
if (prtd->dma_pos >= prtd->dma_end)
prtd->dma_pos = prtd->dma_start;
if (substream)
snd_pcm_period_elapsed(substream);
spin_lock(&prtd->lock);
if (!samsung_dma_has_circular()) {
prtd->dma_loaded--;
dma_enqueue(substream);
}
spin_unlock(&prtd->lock);
}
}
static int dma_hw_params(struct snd_pcm_substream *substream,
struct snd_pcm_hw_params *params)
{
struct snd_pcm_runtime *runtime = substream->runtime;
struct runtime_data *prtd = runtime->private_data;
struct snd_soc_pcm_runtime *rtd = substream->private_data;
unsigned long totbytes = params_buffer_bytes(params);
struct s3c_dma_params *dma =
snd_soc_dai_get_dma_data(rtd->cpu_dai, substream);
struct samsung_dma_req req;
struct samsung_dma_config config;
pr_debug("Entered %s\n", __func__);
/* return if this is a bufferless transfer e.g.
* codec <--> BT codec or GSM modem -- lg FIXME */
if (!dma)
return 0;
/* this may get called several times by oss emulation
* with different params -HW */
if (prtd->params == NULL) {
/* prepare DMA */
prtd->params = dma;
pr_debug("params %p, client %p, channel %d\n", prtd->params,
prtd->params->client, prtd->params->channel);
prtd->params->ops = samsung_dma_get_ops();
req.cap = (samsung_dma_has_circular() ?
DMA_CYCLIC : DMA_SLAVE);
req.client = prtd->params->client;
config.direction =
(substream->stream == SNDRV_PCM_STREAM_PLAYBACK
? DMA_MEM_TO_DEV : DMA_DEV_TO_MEM);
config.width = prtd->params->dma_size;
config.fifo = prtd->params->dma_addr;
prtd->params->ch = prtd->params->ops->request(
prtd->params->channel, &req, rtd->cpu_dai->dev,
prtd->params->ch_name);
if (!prtd->params->ch) {
pr_err("Failed to allocate DMA channel\n");
return -ENXIO;
}
prtd->params->ops->config(prtd->params->ch, &config);
}
snd_pcm_set_runtime_buffer(substream, &substream->dma_buffer);
runtime->dma_bytes = totbytes;
spin_lock_irq(&prtd->lock);
prtd->dma_loaded = 0;
prtd->dma_period = params_period_bytes(params);
prtd->dma_start = runtime->dma_addr;
prtd->dma_pos = prtd->dma_start;
prtd->dma_end = prtd->dma_start + totbytes;
spin_unlock_irq(&prtd->lock);
return 0;
}
static int dma_hw_free(struct snd_pcm_substream *substream)
{
struct runtime_data *prtd = substream->runtime->private_data;
pr_debug("Entered %s\n", __func__);
snd_pcm_set_runtime_buffer(substream, NULL);
if (prtd->params) {
prtd->params->ops->flush(prtd->params->ch);
prtd->params->ops->release(prtd->params->ch,
prtd->params->client);
prtd->params = NULL;
}
return 0;
}
static int dma_prepare(struct snd_pcm_substream *substream)
{
struct runtime_data *prtd = substream->runtime->private_data;
int ret = 0;
pr_debug("Entered %s\n", __func__);
/* return if this is a bufferless transfer e.g.
* codec <--> BT codec or GSM modem -- lg FIXME */
if (!prtd->params)
return 0;
/* flush the DMA channel */
prtd->params->ops->flush(prtd->params->ch);
prtd->dma_loaded = 0;
prtd->dma_pos = prtd->dma_start;
/* enqueue dma buffers */
dma_enqueue(substream);
return ret;
}
static int dma_trigger(struct snd_pcm_substream *substream, int cmd)
{
struct runtime_data *prtd = substream->runtime->private_data;
int ret = 0;
pr_debug("Entered %s\n", __func__);
spin_lock(&prtd->lock);
switch (cmd) {
case SNDRV_PCM_TRIGGER_START:
prtd->state |= ST_RUNNING;
prtd->params->ops->trigger(prtd->params->ch);
break;
case SNDRV_PCM_TRIGGER_STOP:
prtd->state &= ~ST_RUNNING;
prtd->params->ops->stop(prtd->params->ch);
break;
default:
ret = -EINVAL;
break;
}
spin_unlock(&prtd->lock);
return ret;
}
static snd_pcm_uframes_t
dma_pointer(struct snd_pcm_substream *substream)
{
struct snd_pcm_runtime *runtime = substream->runtime;
struct runtime_data *prtd = runtime->private_data;
unsigned long res;
pr_debug("Entered %s\n", __func__);
res = prtd->dma_pos - prtd->dma_start;
pr_debug("Pointer offset: %lu\n", res);
/* we seem to be getting the odd error from the pcm library due
* to out-of-bounds pointers. this is maybe due to the dma engine
* not having loaded the new values for the channel before being
* called... (todo - fix )
*/
if (res >= snd_pcm_lib_buffer_bytes(substream)) {
if (res == snd_pcm_lib_buffer_bytes(substream))
res = 0;
}
return bytes_to_frames(substream->runtime, res);
}
static int dma_open(struct snd_pcm_substream *substream)
{
struct snd_pcm_runtime *runtime = substream->runtime;
struct runtime_data *prtd;
pr_debug("Entered %s\n", __func__);
snd_pcm_hw_constraint_integer(runtime, SNDRV_PCM_HW_PARAM_PERIODS);
snd_soc_set_runtime_hwparams(substream, &dma_hardware);
prtd = kzalloc(sizeof(struct runtime_data), GFP_KERNEL);
if (prtd == NULL)
return -ENOMEM;
spin_lock_init(&prtd->lock);
runtime->private_data = prtd;
return 0;
}
static int dma_close(struct snd_pcm_substream *substream)
{
struct snd_pcm_runtime *runtime = substream->runtime;
struct runtime_data *prtd = runtime->private_data;
pr_debug("Entered %s\n", __func__);
if (!prtd)
pr_debug("dma_close called with prtd == NULL\n");
kfree(prtd);
return 0;
}
static int dma_mmap(struct snd_pcm_substream *substream,
struct vm_area_struct *vma)
{
struct snd_pcm_runtime *runtime = substream->runtime;
pr_debug("Entered %s\n", __func__);
return dma_mmap_writecombine(substream->pcm->card->dev, vma,
runtime->dma_area,
runtime->dma_addr,
runtime->dma_bytes);
}
static struct snd_pcm_ops dma_ops = {
.open = dma_open,
.close = dma_close,
.ioctl = snd_pcm_lib_ioctl,
.hw_params = dma_hw_params,
.hw_free = dma_hw_free,
.prepare = dma_prepare,
.trigger = dma_trigger,
.pointer = dma_pointer,
.mmap = dma_mmap,
};
static int preallocate_dma_buffer(struct snd_pcm *pcm, int stream)
{
struct snd_pcm_substream *substream = pcm->streams[stream].substream;
struct snd_dma_buffer *buf = &substream->dma_buffer;
size_t size = dma_hardware.buffer_bytes_max;
pr_debug("Entered %s\n", __func__);
buf->dev.type = SNDRV_DMA_TYPE_DEV;
buf->dev.dev = pcm->card->dev;
buf->private_data = NULL;
buf->area = dma_alloc_writecombine(pcm->card->dev, size,
&buf->addr, GFP_KERNEL);
if (!buf->area)
return -ENOMEM;
buf->bytes = size;
return 0;
}
static void dma_free_dma_buffers(struct snd_pcm *pcm)
{
struct snd_pcm_substream *substream;
struct snd_dma_buffer *buf;
int stream;
pr_debug("Entered %s\n", __func__);
for (stream = 0; stream < 2; stream++) {
substream = pcm->streams[stream].substream;
if (!substream)
continue;
buf = &substream->dma_buffer;
if (!buf->area)
continue;
dma_free_writecombine(pcm->card->dev, buf->bytes,
buf->area, buf->addr);
buf->area = NULL;
}
}
static u64 dma_mask = DMA_BIT_MASK(32);
static int dma_new(struct snd_soc_pcm_runtime *rtd)
{
struct snd_card *card = rtd->card->snd_card;
struct snd_pcm *pcm = rtd->pcm;
int ret = 0;
pr_debug("Entered %s\n", __func__);
if (!card->dev->dma_mask)
card->dev->dma_mask = &dma_mask;
if (!card->dev->coherent_dma_mask)
card->dev->coherent_dma_mask = DMA_BIT_MASK(32);
if (pcm->streams[SNDRV_PCM_STREAM_PLAYBACK].substream) {
ret = preallocate_dma_buffer(pcm,
SNDRV_PCM_STREAM_PLAYBACK);
if (ret)
goto out;
}
if (pcm->streams[SNDRV_PCM_STREAM_CAPTURE].substream) {
ret = preallocate_dma_buffer(pcm,
SNDRV_PCM_STREAM_CAPTURE);
if (ret)
goto out;
}
out:
return ret;
}
static struct snd_soc_platform_driver samsung_asoc_platform = {
.ops = &dma_ops,
.pcm_new = dma_new,
.pcm_free = dma_free_dma_buffers,
};
int samsung_asoc_dma_platform_register(struct device *dev)
{
return snd_soc_register_platform(dev, &samsung_asoc_platform);
}
EXPORT_SYMBOL_GPL(samsung_asoc_dma_platform_register);
void samsung_asoc_dma_platform_unregister(struct device *dev)
{
snd_soc_unregister_platform(dev);
}
EXPORT_SYMBOL_GPL(samsung_asoc_dma_platform_unregister);
MODULE_AUTHOR("Ben Dooks, <ben@simtec.co.uk>");
MODULE_DESCRIPTION("Samsung ASoC DMA Driver");
MODULE_LICENSE("GPL");
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