From: Daniel Girnus dgirnus@de.adit-jv.com
Some of userland applications call 'snd_pcm_hw_params()' and 'snd_pcm_hw_prepare()' sequentially, which means 'snd_pcm_hw_prepare()' is called twice and the second 'snd_pcm_hw_prepare()' is called in 'SNDRV_PCM_STATE_PREPARED' state.
Some devices are not able to manage this and they will stop playback if the sample rate will be configured several times over USB protocol.
V2: updated Changelog
Signed-off-by: Daniel Girnus dgirnus@de.adit-jv.com Signed-off-by: Jens Lorenz jlorenz@de.adit-jv.com Signed-off-by: Jiada Wang jiada_wang@mentor.com --- sound/usb/pcm.c | 21 +++++++++++---------- 1 file changed, 11 insertions(+), 10 deletions(-)
diff --git a/sound/usb/pcm.c b/sound/usb/pcm.c index 44d178e..a522c9a 100644 --- a/sound/usb/pcm.c +++ b/sound/usb/pcm.c @@ -806,17 +806,18 @@ static int snd_usb_pcm_prepare(struct snd_pcm_substream *substream) if (ret < 0) goto unlock;
- iface = usb_ifnum_to_if(subs->dev, subs->cur_audiofmt->iface); - alts = &iface->altsetting[subs->cur_audiofmt->altset_idx]; - ret = snd_usb_init_sample_rate(subs->stream->chip, - subs->cur_audiofmt->iface, - alts, - subs->cur_audiofmt, - subs->cur_rate); - if (ret < 0) - goto unlock; - if (subs->need_setup_ep) { + + iface = usb_ifnum_to_if(subs->dev, subs->cur_audiofmt->iface); + alts = &iface->altsetting[subs->cur_audiofmt->altset_idx]; + ret = snd_usb_init_sample_rate(subs->stream->chip, + subs->cur_audiofmt->iface, + alts, + subs->cur_audiofmt, + subs->cur_rate); + if (ret < 0) + goto unlock; + ret = configure_endpoint(subs); if (ret < 0) goto unlock;