[alsa-devel] Will ALSA ever call _prepare or _hw_params while it's playing?
I have an ASoC driver with a _hw_params, _prepare, and _trigger functions. I've recently discovered that I need to keep one of my devices disabled until playback starts.
So I would like to know if ALSA will ever call _hw_params, _prepare, or _startup if playback or capture is currently in process, or will ALSA first call the _trigger to stop/pause the driver.
If ALSA does stop/pause the driver before changing parameters, then I can safely assume the device is always disabled during those functions.
Timur Tabi wrote:
I have an ASoC driver with a _hw_params, _prepare, and _trigger functions. I've recently discovered that I need to keep one of my devices disabled until playback starts.
So I would like to know if ALSA will ever call _hw_params, _prepare, or _trigger if playback or capture is currently in process, or will ALSA first call the _trigger to stop/pause the driver.
While a stream is running (after trigger with START), ALSA will only call the pointer or the trigger (STOP/PAUSE/SUSPEND) callbacks.
Different streams are not synchronized in any way. (This also applies to the playback/capture streams of one card.)
Regards, Clemens
Clemens Ladisch wrote:
Timur Tabi wrote:
I have an ASoC driver with a _hw_params, _prepare, and _trigger functions. I've recently discovered that I need to keep one of my devices disabled until playback starts.
So I would like to know if ALSA will ever call _hw_params, _prepare, or _trigger if playback or capture is currently in process, or will ALSA first call the _trigger to stop/pause the driver.
While a stream is running (after trigger with START), ALSA will only call the pointer or the trigger (STOP/PAUSE/SUSPEND) callbacks.
That's good.
Different streams are not synchronized in any way. (This also applies to the playback/capture streams of one card.)
Ah, I hadn't thought about that. If I'm doing simultaneous capture and playback through the same device, then I can't guarantee that it's disabled. Argh.
Thanks.
participants (2)
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Clemens Ladisch -
Timur Tabi