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ALSA: pcm: Introduce managed buffer allocation mode

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This patch adds the support for the feature to automatically allocate
and free PCM buffers, so called "managed buffer allocation" mode.
It's set up via new PCM helpers, snd_pcm_set_managed_buffer() and
snd_pcm_set_managed_buffer_all(), both of which correspond to the
existing preallocator helpers, snd_pcm_lib_preallocate_pages() and
snd_pcm_lib_preallocate_pages_for_all().  When the new helper is used,
it not only performs the pre-allocation of buffers, but also it
manages to call snd_pcm_lib_malloc_pages() before the PCM hw_params
ops and snd_lib_pcm_free() after the PCM hw_free ops inside PCM core,
respectively.  This allows drivers to drop the explicit calls of the
memory allocation / release functions, and it will be a good amount of
code reduction in the end of this patch series.

When the PCM substream is set to the managed buffer allocation mode,
the managed_buffer_alloc flag is set in the substream object.  Since
some drivers want to know when a buffer is newly allocated or
re-allocated at hw_params callback (e.g. want to set up the additional
stuff for the given buffer only at allocation time), now PCM core
turns on buffer_changed flag when the buffer has changed.

The standard conversions to use the new API will be straightforward:
- Replace snd_pcm_lib_preallocate*() calls with the corresponding
  snd_pcm_set_managed_buffer*(); the arguments should be unchanged
- Drop superfluous snd_pcm_lib_malloc() and snd_pcm_lib_free() calls;
  the check of snd_pcm_lib_malloc() returns should be replaced with
  the check of runtime->buffer_changed flag.
- If hw_params or hw_free becomes empty, drop them from PCM ops

Link: https://lore.kernel.org/r/20191117085308.23915-2-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>
This commit is contained in:
Takashi Iwai 2019-11-17 09:53:01 +01:00
parent c6ae996056
commit 0dba808eae
3 changed files with 90 additions and 13 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

8
include/sound/pcm.h
View File

@ -414,6 +414,7 @@ struct snd_pcm_runtime {
size_t dma_bytes; /* size of DMA area */
struct snd_dma_buffer *dma_buffer_p; /* allocated buffer */
unsigned int buffer_changed:1; /* buffer allocation changed; set only in managed mode */
/* -- audio timestamp config -- */
struct snd_pcm_audio_tstamp_config audio_tstamp_config;
@ -475,6 +476,7 @@ struct snd_pcm_substream {
#endif /* CONFIG_SND_VERBOSE_PROCFS */
/* misc flags */
unsigned int hw_opened: 1;
unsigned int managed_buffer_alloc:1;
};
#define SUBSTREAM_BUSY(substream) ((substream)->ref_count > 0)
@ -1186,6 +1188,12 @@ void snd_pcm_lib_preallocate_pages_for_all(struct snd_pcm *pcm,
int snd_pcm_lib_malloc_pages(struct snd_pcm_substream *substream, size_t size);
int snd_pcm_lib_free_pages(struct snd_pcm_substream *substream);
void snd_pcm_set_managed_buffer(struct snd_pcm_substream *substream, int type,
struct device *data, size_t size, size_t max);
void snd_pcm_set_managed_buffer_all(struct snd_pcm *pcm, int type,
struct device *data,
size_t size, size_t max);
int _snd_pcm_lib_alloc_vmalloc_buffer(struct snd_pcm_substream *substream,
size_t size, gfp_t gfp_flags);
int snd_pcm_lib_free_vmalloc_buffer(struct snd_pcm_substream *substream);

83
sound/core/pcm_memory.c
View File

@ -193,9 +193,15 @@ static inline void preallocate_info_init(struct snd_pcm_substream *substream)
/*
* pre-allocate the buffer and create a proc file for the substream
*/
static void snd_pcm_lib_preallocate_pages1(struct snd_pcm_substream *substream,
size_t size, size_t max)
static void preallocate_pages(struct snd_pcm_substream *substream,
int type, struct device *data,
size_t size, size_t max, bool managed)
{
if (snd_BUG_ON(substream->dma_buffer.dev.type))
return;
substream->dma_buffer.dev.type = type;
substream->dma_buffer.dev.dev = data;
if (size > 0 && preallocate_dma && substream->number < maximum_substreams)
preallocate_pcm_pages(substream, size);
@ -205,8 +211,23 @@ static void snd_pcm_lib_preallocate_pages1(struct snd_pcm_substream *substream,
substream->dma_max = max;
if (max > 0)
preallocate_info_init(substream);
if (managed)
substream->managed_buffer_alloc = 1;
}
static void preallocate_pages_for_all(struct snd_pcm *pcm, int type,
void *data, size_t size, size_t max,
bool managed)
{
struct snd_pcm_substream *substream;
int stream;
for (stream = 0; stream < 2; stream++)
for (substream = pcm->streams[stream].substream; substream;
substream = substream->next)
preallocate_pages(substream, type, data, size, max,
managed);
}
/**
* snd_pcm_lib_preallocate_pages - pre-allocation for the given DMA type
@ -222,11 +243,7 @@ void snd_pcm_lib_preallocate_pages(struct snd_pcm_substream *substream,
int type, struct device *data,
size_t size, size_t max)
{
if (snd_BUG_ON(substream->dma_buffer.dev.type))
return;
substream->dma_buffer.dev.type = type;
substream->dma_buffer.dev.dev = data;
snd_pcm_lib_preallocate_pages1(substream, size, max);
preallocate_pages(substream, type, data, size, max, false);
}
EXPORT_SYMBOL(snd_pcm_lib_preallocate_pages);
@ -245,15 +262,55 @@ void snd_pcm_lib_preallocate_pages_for_all(struct snd_pcm *pcm,
int type, void *data,
size_t size, size_t max)
{
struct snd_pcm_substream *substream;
int stream;
for (stream = 0; stream < 2; stream++)
for (substream = pcm->streams[stream].substream; substream; substream = substream->next)
snd_pcm_lib_preallocate_pages(substream, type, data, size, max);
preallocate_pages_for_all(pcm, type, data, size, max, false);
}
EXPORT_SYMBOL(snd_pcm_lib_preallocate_pages_for_all);
/**
* snd_pcm_set_managed_buffer - set up buffer management for a substream
* @substream: the pcm substream instance
* @type: DMA type (SNDRV_DMA_TYPE_*)
* @data: DMA type dependent data
* @size: the requested pre-allocation size in bytes
* @max: the max. allowed pre-allocation size
*
* Do pre-allocation for the given DMA buffer type, and set the managed
* buffer allocation mode to the given substream.
* In this mode, PCM core will allocate a buffer automatically before PCM
* hw_params ops call, and release the buffer after PCM hw_free ops call
* as well, so that the driver doesn't need to invoke the allocation and
* the release explicitly in its callback.
* When a buffer is actually allocated before the PCM hw_params call, it
* turns on the runtime buffer_changed flag for drivers changing their h/w
* parameters accordingly.
*/
void snd_pcm_set_managed_buffer(struct snd_pcm_substream *substream, int type,
struct device *data, size_t size, size_t max)
{
preallocate_pages(substream, type, data, size, max, true);
}
EXPORT_SYMBOL(snd_pcm_set_managed_buffer);
/**
* snd_pcm_set_managed_buffer_all - set up buffer management for all substreams
* for all substreams
* @pcm: the pcm instance
* @type: DMA type (SNDRV_DMA_TYPE_*)
* @data: DMA type dependent data
* @size: the requested pre-allocation size in bytes
* @max: the max. allowed pre-allocation size
*
* Do pre-allocation to all substreams of the given pcm for the specified DMA
* type and size, and set the managed_buffer_alloc flag to each substream.
*/
void snd_pcm_set_managed_buffer_all(struct snd_pcm *pcm, int type,
struct device *data,
size_t size, size_t max)
{
preallocate_pages_for_all(pcm, type, data, size, max, true);
}
EXPORT_SYMBOL(snd_pcm_set_managed_buffer_all);
#ifdef CONFIG_SND_DMA_SGBUF
/*
* snd_pcm_sgbuf_ops_page - get the page struct at the given offset

12
sound/core/pcm_native.c
View File

@ -662,6 +662,14 @@ static int snd_pcm_hw_params(struct snd_pcm_substream *substream,
if (err < 0)
goto _error;
if (substream->managed_buffer_alloc) {
err = snd_pcm_lib_malloc_pages(substream,
params_buffer_bytes(params));
if (err < 0)
goto _error;
runtime->buffer_changed = err > 0;
}
if (substream->ops->hw_params != NULL) {
err = substream->ops->hw_params(substream, params);
if (err < 0)
@ -723,6 +731,8 @@ static int snd_pcm_hw_params(struct snd_pcm_substream *substream,
snd_pcm_set_state(substream, SNDRV_PCM_STATE_OPEN);
if (substream->ops->hw_free != NULL)
substream->ops->hw_free(substream);
if (substream->managed_buffer_alloc)
snd_pcm_lib_free_pages(substream);
return err;
}
@ -769,6 +779,8 @@ static int snd_pcm_hw_free(struct snd_pcm_substream *substream)
return -EBADFD;
if (substream->ops->hw_free)
result = substream->ops->hw_free(substream);
if (substream->managed_buffer_alloc)
snd_pcm_lib_free_pages(substream);
snd_pcm_set_state(substream, SNDRV_PCM_STATE_OPEN);
pm_qos_remove_request(&substream->latency_pm_qos_req);
return result;