[alsa-devel] [PATCH v2 0/3] Allow suspend/resume with USB audio.

Dylan Reid dgreid at chromium.org
Tue Sep 18 18:49:45 CEST 2012

Problem being addressed:
shell one$ aplay -Dhw:<usbcard> file.wav
shell two$ echo mem > /sys/power/state
After resume, aplay attempts resume, then restart, then after a timeout
gets a write error and no audio will be played until it is restarted.

During suspend/resume, if the USB port remains powered the audio device
will still be present upon resume.  The interface and endpoint have to
be reconfigured however.  These patches move the configuration from
hw_params to prepare causing re-configuration during resume.

Is this the right way to fix this?  Or is there an easier way I am

Thanks for looking.

v2: fix unused variable warnings.

Dylan Reid (3):
  ALSA: usb-audio: set period_bytes in substream.
  ALSA: usb-audio: Don't require hw_params in endpoint.
  ALSA: usb-audio: Move configuration to prepare.

 sound/usb/card.h     |   2 +
 sound/usb/endpoint.c |  29 +++++++-----
 sound/usb/endpoint.h |   5 ++-
 sound/usb/pcm.c      | 121 +++++++++++++++++++++++++++++++--------------------
 4 files changed, 97 insertions(+), 60 deletions(-)


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