On Wed, 30 Nov 2016 08:59:22 +0100,
Jiada Wang wrote:
>
> From: Daniel Girnus <dgirnus@xxxxxxxxxxxxxx>
>
> ALSA usually calls the prepare function twice before starting the playback:
> 1. On hw_params call from userland and
> 2. internally when starting the stream.
> Some device are not able to manage this and they will stop playback
> if the sample rate will be configured several times over USB protocol.
>
> Signed-off-by: Jens Lorenz <jlorenz@xxxxxxxxxxxxxx>
> Signed-off-by: Jiada Wang <jiada_wang@xxxxxxxxxx>
The sign-off from Daniel seems missing?
The code change looks OK, but it'd be nice to mention in the changelog
that, after this patch, snd_usb_init_sample_rate() is still called
properly whenever the parameter is changed since ep->need_setup_ep is
set in snd_hsb_hw_params().
thanks,
Takashi
> ---
> 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;
> --
> 2.9.3
>
>
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