Commit ea2ddd25 authored by Pierre-Louis Bossart's avatar Pierre-Louis Bossart Committed by Takashi Iwai
Browse files

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: default avatarPierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Reviewed-by: default avatarBard Liao <yung-chuan.liao@linux.intel.com>
Reviewed-by: default avatarPéter Ujfalusi <peter.ujfalusi@linux.intel.com>
Reviewed-by: default avatarKai Vehmanen <kai.vehmanen@linux.intel.com>
Link: https://lore.kernel.org/r/20220919121041.43463-3-pierre-louis.bossart@linux.intel.com


Signed-off-by: default avatarTakashi Iwai <tiwai@suse.de>
parent 2ea13c83

sound/hda/hdac_stream.c

+33 −0
Original line number Diff line number Diff line
@@ -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