Hans-Christian Egtvedt wrote: > Okay, so to be sure I setup and release my cyclic DMA buffer safely I > could use the following model: > > in prepare callback setup the DMA buffer, once when called. The > hardware parameters should not change at this point. > > If I get a hw_params callback after a prepare, then release the DMA > buffer, and set it up again in the prepare callback? > > Final cleanup of the DMA buffer can/should be done in hw_free? This would work, but doing it in the hw_params callback would be a little more simple: * In hw_params, free the old buffer (if it exists), then setup the buffer; * in hw_free, free the buffer. As a rule of thumb, the callbacks open/close, hw_params/hw_free and start/stop trigger are mostly symmetrical, and any resources should be allocated and freed in the functions that belong together. (The start trigger is a special case because it uses two callbacks, prepare and trigger with TRIGGER_START.) The hw_params and prepare callbacks can be called multiple times. > Is there a flow chart which shows how the different callbacks can be > called? Not yet. Best regards, Clemens _______________________________________________ Alsa-devel mailing list Alsa-devel@xxxxxxxxxxxxxxxx http://mailman.alsa-project.org/mailman/listinfo/alsa-devel
