ALSA: pcm: optimize and clarify stream synchronization ID API (d712c58c) · Commits · git / linux-net

include/sound/pcm.h

+13 −2

Original line number	Diff line number	Diff line
		@@ -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);

sound/core/pcm_lib.c

+31 −20

Original line number	Diff line number	Diff line
		@@ -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;
		}

sound/pci/emu10k1/p16v.c

+12 −4

Original line number	Diff line number	Diff line
		@@ -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,