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| author | Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com> | 2022-09-19 14:10:35 +0200 |
|---|---|---|
| committer | Takashi Iwai <tiwai@suse.de> | 2022-09-20 08:08:13 +0200 |
| commit | ea2ddd2559dc6d1c4b66ccd49314add35ece9062 (patch) | |
| tree | b4950a2a99198d864afa45b4657f735491063d8a /sound/hda | |
| parent | 2ea13c83bf7bb3471e33b2d902b101af977ef2d4 (diff) | |
| download | linux-ea2ddd2559dc6d1c4b66ccd49314add35ece9062.tar.bz2 | |
ALSA: hda: document state machine for hdac_streams
The code in this library is far from self-explanatory, hopefully this
state diagram reverse-engineered from the code will help others
understand the expected transitions.
Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Reviewed-by: Bard Liao <yung-chuan.liao@linux.intel.com>
Reviewed-by: Péter Ujfalusi <peter.ujfalusi@linux.intel.com>
Reviewed-by: Kai Vehmanen <kai.vehmanen@linux.intel.com>
Link: https://lore.kernel.org/r/20220919121041.43463-3-pierre-louis.bossart@linux.intel.com
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Diffstat (limited to 'sound/hda')
| -rw-r--r-- | sound/hda/hdac_stream.c | 33 |
1 files changed, 33 insertions, 0 deletions
diff --git a/sound/hda/hdac_stream.c b/sound/hda/hdac_stream.c index 2dbde3d1cf68..2e98f5fd50e5 100644 --- a/sound/hda/hdac_stream.c +++ b/sound/hda/hdac_stream.c @@ -13,6 +13,39 @@ #include <sound/hda_register.h> #include "trace.h" +/* + * the hdac_stream library is intended to be used with the following + * transitions. The states are not formally defined in the code but loosely + * inspired by boolean variables. Note that the 'prepared' field is not used + * in this library but by the callers during the hw_params/prepare transitions + * + * | + * stream_init() | + * v + * +--+-------+ + * | unused | + * +--+----+--+ + * | ^ + * stream_assign() | | stream_release() + * v | + * +--+----+--+ + * | opened | + * +--+----+--+ + * | ^ + * stream_reset() | | + * stream_setup() | | stream_cleanup() + * v | + * +--+----+--+ + * | prepared | + * +--+----+--+ + * | ^ + * stream_start() | | stream_stop() + * v | + * +--+----+--+ + * | running | + * +----------+ + */ + /** * snd_hdac_get_stream_stripe_ctl - get stripe control value * @bus: HD-audio core bus |