pcm: add documentation for -ENODATA error code

This error code can be used e.g. with echo reference PCM devices
(the SND_USE_CASE_MOD_ECHO_REF UCM token).

Signed-off-by: Kai Vehmanen <kai.vehmanen@linux.intel.com>
This commit is contained in:
Kai Vehmanen 2020-05-29 15:28:16 +03:00 committed by Jaroslav Kysela
parent 33089f30a3
commit 275409fee3

View file

@ -292,6 +292,14 @@ This error can happen when device is physically removed (for example
some hotplug devices like USB or PCMCIA, CardBus or ExpressCard
can be removed on the fly).
\par -ENODATA
This error can happen if the device data transfer is dependent on
an external condition and that condition is not met. For example,
PCM device for echo reference as described by SND_USE_CASE_MOD_ECHO_REF
UCM token, may return -ENODATA if the linked playback stream has not been
started.
\section pcm_params Managing parameters
The ALSA PCM device uses two groups of PCM related parameters. The hardware