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ALSA: pcm: optimize and clarify stream synchronization ID API

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Optimize the memory usage in struct snd_pcm_runtime - use boolean
value for the standard sync ID scheme.

Introduce snd_pcm_set_sync_per_card function to build synchronization
IDs.

Signed-off-by: Jaroslav Kysela <perex@perex.cz>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Link: https://patch.msgid.link/20240625172836.589380-3-perex@perex.cz
This commit is contained in:
Jaroslav Kysela 2024-06-25 19:25:47 +02:00 committed by Takashi Iwai
parent f05c1ffc27
commit d712c58c55
3 changed files with 56 additions and 26 deletions
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15
include/sound/pcm.h
View File

@ -402,7 +402,7 @@ struct snd_pcm_runtime {
snd_pcm_uframes_t silence_start; /* starting pointer to silence area */
snd_pcm_uframes_t silence_filled; /* already filled part of silence area */
unsigned char sync[16]; /* hardware synchronization ID */
bool std_sync_id; /* hardware synchronization - standard per card ID */
/* -- mmap -- */
struct snd_pcm_mmap_status *status;
@ -1156,7 +1156,18 @@ int snd_pcm_format_set_silence(snd_pcm_format_t format, void *buf, unsigned int
void snd_pcm_set_ops(struct snd_pcm * pcm, int direction,
const struct snd_pcm_ops *ops);
void snd_pcm_set_sync(struct snd_pcm_substream *substream);
void snd_pcm_set_sync_per_card(struct snd_pcm_substream *substream, struct snd_pcm_hw_params *params,
const unsigned char *id, unsigned int len);
/**
* snd_pcm_set_sync - set the PCM sync id
* @substream: the pcm substream
*
* Use the default PCM sync identifier for the specific card.
*/
static inline void snd_pcm_set_sync(struct snd_pcm_substream *substream)
{
substream->runtime->std_sync_id = true;
}
int snd_pcm_lib_ioctl(struct snd_pcm_substream *substream,
unsigned int cmd, void *arg);
void snd_pcm_period_elapsed_under_stream_lock(struct snd_pcm_substream *substream);

51
sound/core/pcm_lib.c
View File

@ -516,19 +516,37 @@ void snd_pcm_set_ops(struct snd_pcm *pcm, int direction,
EXPORT_SYMBOL(snd_pcm_set_ops);
/**
* snd_pcm_set_sync - set the PCM sync id
* snd_pcm_set_sync_per_card - set the PCM sync id with card number
* @substream: the pcm substream
* @params: modified hardware parameters
* @id: identifier (max 12 bytes)
* @len: identifier length (max 12 bytes)
*
* Sets the PCM sync identifier for the card.
* Sets the PCM sync identifier for the card with zero padding.
*
* User space or any user should use this 16-byte identifier for a comparison only
* to check if two IDs are similar or different. Special case is the identifier
* containing only zeros. Interpretation for this combination is - empty (not set).
* The contents of the identifier should not be interpreted in any other way.
*
* The synchronization ID must be unique per clock source (usually one sound card,
* but multiple soundcard may use one PCM word clock source which means that they
* are fully synchronized).
*
* This routine composes this ID using card number in first four bytes and
* 12-byte additional ID. When other ID composition is used (e.g. for multiple
* sound cards), make sure that the composition does not clash with this
* composition scheme.
*/
void snd_pcm_set_sync(struct snd_pcm_substream *substream)
void snd_pcm_set_sync_per_card(struct snd_pcm_substream *substream,
struct snd_pcm_hw_params *params,
const unsigned char *id, unsigned int len)
{
struct snd_pcm_runtime *runtime = substream->runtime;
*(__u32 *)runtime->sync = cpu_to_le32(substream->pcm->card->number);
memset(runtime->sync + 4, 0xff, sizeof(runtime->sync) - 4);
*(__u32 *)params->sync = cpu_to_le32(substream->pcm->card->number);
len = max(12, len);
strncpy(params->sync + 4, id, len);
memset(params->sync + 4 + len, 0, 12 - len);
}
EXPORT_SYMBOL(snd_pcm_set_sync);
/*
* Standard ioctl routine
@ -1808,22 +1826,15 @@ static int snd_pcm_lib_ioctl_fifo_size(struct snd_pcm_substream *substream,
return 0;
}
/**
* is sync id (clock id) empty?
*/
static inline bool pcm_sync_empty(const unsigned char *sync)
{
return sync[0] == 0 && sync[1] == 0 && sync[2] == 0 && sync[3] == 0 &&
sync[4] == 0 && sync[5] == 0 && sync[6] == 0 && sync[7] == 0;
}
static int snd_pcm_lib_ioctl_sync_id(struct snd_pcm_substream *substream,
void *arg)
{
struct snd_pcm_hw_params *params = arg;
static const unsigned char id[12] = { 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff };
if (pcm_sync_empty(params->sync))
memcpy(params->sync, substream->runtime->sync, sizeof(params->sync));
if (substream->runtime->std_sync_id)
snd_pcm_set_sync_per_card(substream, arg, id, sizeof(id));
return 0;
}

16
sound/pci/emu10k1/p16v.c
View File

@ -174,10 +174,6 @@ static int snd_p16v_pcm_open_playback_channel(struct snd_pcm_substream *substrea
if (err < 0)
return err;
*(__u32 *)runtime->sync = cpu_to_le32(substream->pcm->card->number);
memset(runtime->sync + 4, 0, sizeof(runtime->sync) - 4);
strncpy(runtime->sync + 4, "P16V", 4);
return 0;
}
@ -225,6 +221,17 @@ static int snd_p16v_pcm_open_capture(struct snd_pcm_substream *substream)
return snd_p16v_pcm_open_capture_channel(substream, 0);
}
static int snd_p16v_pcm_ioctl_playback(struct snd_pcm_substream *substream,
unsigned int cmd, void *arg)
{
if (cmd == SNDRV_PCM_IOCTL1_SYNC_ID) {
static const unsigned char id[4] = { 'P', '1', '6', 'V' };
snd_pcm_set_sync_per_card(substream, arg, id, 4);
return 0;
}
return snd_pcm_lib_ioctl(substream, cmd, arg);
}
/* prepare playback callback */
static int snd_p16v_pcm_prepare_playback(struct snd_pcm_substream *substream)
{
@ -530,6 +537,7 @@ snd_p16v_pcm_pointer_capture(struct snd_pcm_substream *substream)
static const struct snd_pcm_ops snd_p16v_playback_front_ops = {
.open = snd_p16v_pcm_open_playback_front,
.close = snd_p16v_pcm_close_playback,
.ioctl = snd_p16v_pcm_ioctl_playback,
.prepare = snd_p16v_pcm_prepare_playback,
.trigger = snd_p16v_pcm_trigger_playback,
.pointer = snd_p16v_pcm_pointer_playback,