Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757485AbcK3IwC (ORCPT ); Wed, 30 Nov 2016 03:52:02 -0500 Received: from mx2.suse.de ([195.135.220.15]:55874 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755681AbcK3Ivw (ORCPT ); Wed, 30 Nov 2016 03:51:52 -0500 Date: Wed, 30 Nov 2016 09:51:48 +0100 Message-ID: From: Takashi Iwai To: "Jiada Wang" Cc: , , , , Subject: Re: [PATCH 2/3 v2] ALSA: usb-audio: avoid setting of sample rate multiple times on bus In-Reply-To: <20161130075923.15205-3-jiada_wang@mentor.com> References: <20161130075923.15205-1-jiada_wang@mentor.com> <20161130075923.15205-3-jiada_wang@mentor.com> User-Agent: Wanderlust/2.15.9 (Almost Unreal) SEMI/1.14.6 (Maruoka) FLIM/1.14.9 (=?UTF-8?B?R29qxY0=?=) APEL/10.8 Emacs/24.5 (x86_64-suse-linux-gnu) MULE/6.0 (HANACHIRUSATO) MIME-Version: 1.0 (generated by SEMI 1.14.6 - "Maruoka") Content-Type: text/plain; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2024 Lines: 67 On Wed, 30 Nov 2016 08:59:22 +0100, Jiada Wang wrote: > > From: Daniel Girnus > > 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 > Signed-off-by: Jiada Wang 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 > >