Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757076AbaAJNeO (ORCPT ); Fri, 10 Jan 2014 08:34:14 -0500 Received: from cantor2.suse.de ([195.135.220.15]:45730 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751691AbaAJNeL (ORCPT ); Fri, 10 Jan 2014 08:34:11 -0500 Date: Fri, 10 Jan 2014 14:34:09 +0100 Message-ID: From: Takashi Iwai To: Nenghua Cao Cc: Liam Girdwood , "alsa-devel@alsa-project.org" , Mark Brown , "linux-kernel@vger.kernel.org" Subject: Re: [alsa-devel] [PATCH] ASoC: dpcm: don't do hw_param when BE has done hw_param In-Reply-To: <52CFE623.7090403@marvell.com> References: <1389332195-15900-1-git-send-email-nhcao@marvell.com> <52CFD7BE.5030907@marvell.com> <1389354435.2293.32.camel@loki> <52CFE0AE.1030606@marvell.com> <52CFE623.7090403@marvell.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/24.3 (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 At Fri, 10 Jan 2014 20:22:59 +0800, Nenghua Cao wrote: > > On 01/10/2014 08:01 PM, Takashi Iwai wrote: > > At Fri, 10 Jan 2014 19:59:42 +0800, > > Nenghua Cao wrote: > >> > >> On 01/10/2014 07:47 PM, Liam Girdwood wrote: > >>> On Fri, 2014-01-10 at 19:21 +0800, Nenghua Cao wrote: > >>>> On 01/10/2014 06:55 PM, Takashi Iwai wrote: > >>>>> [Corrected mail addresses of both Mark and Liam] > >>>>> > >>>> Hi, Takashi: > >>>> Thanks for correcting my mistake. > >>>>> At Fri, 10 Jan 2014 13:36:35 +0800, > >>>>> Nenghua Cao wrote: > >>>>>> > >>>>>> From: Nenghua Cao > >>>>>> > >>>>>> It fixes the following case: > >>>>>> Two FEs connects the same BE; FE1 & BE path has been opened and hw_paramed. > >>>>>> At this momment, FE2 & BE path is being opened and hw_paramed. The BE > >>>>>> dai will do hw_param again even if it has done hw_param. It is not > >>>>>> reasonable. > >>>>>> FE1------------>BE > >>>>>> FE2-------------^ > >>>>> > >>>>> What happens if FE2 tries to set up an incompatible hw_params? > >>>>> (Through a quick glance, it won't work properly well, too, though...) > >>>>> > >>> > >>> The intention in this case would be for the DSP FE driver to determine > >>> if it can perform format conversion or SRC to the running BE. If the DSP > >>> cant do the conversion then it should fail. > >>> > >>>> If FE2 uses an incompatible param, it will make FE1 doesn't work. Maybe > >>>> FE2 works well. > >>>> If FE2 uses the same param, BE hw_param function will be called twice > >>>> (This is the most happening case). > >>>> So we can't get benefits from it. > >>> > >>> We shouldn't be calling the hw_params() on the BE when it's already > >>> configured in this case. So this seems like a bug. However :- > >>> > >>> /* only allow hw_params() if no connected FEs are running */ > >>> if (!snd_soc_dpcm_can_be_params(fe, be, stream)) > >>> continue; > >>> > >>> if ((be->dpcm[stream].state != SND_SOC_DPCM_STATE_OPEN) && > >>> (be->dpcm[stream].state != SND_SOC_DPCM_STATE_HW_PARAMS) && > >>> (be->dpcm[stream].state != SND_SOC_DPCM_STATE_HW_FREE)) > >>> continue; > >>> > >>> We do do a test to check if any connected FEs are running (i.e. > >>> triggered) prior to calling hw_params() on the BE. Can you confirm if > >>> the FE was running in your case ? > >>> > >> Hi, Liam: > >> I am so glad to hear from you. In my case, FE1 has called hw_param, > >> and before FE1 calls prepare/trigger function, the scheduler switches to > >> do FE2 open, hw_param. So hw_param is called twice. > > > > So basically the current implementation is racy about this. > > > > OTOH, not calling hw_params twice is also buggy. hw_params may be > > called multiple times without hw_free for the same stream if user > > wants to re-setup/update the parameters. OSS emulation layer does it, > > for example. > > > Hi, Takashi > > On current alsa framework, the hw_param can be called multiple time. > Here, FE1 also can call do it. But it won't any longer if your patch is applied, no? Takashi > But here we should add constraint to > avoid another FE call it due to FE1 has choose it priority. > > > > > Takashi > > > >> > >>> Thanks > >>> > >>> Liam > >>> > >>>>> > >>>>> Takashi > >>>>> > >>>>>> > >>>>>> Signed-off-by: Nenghua Cao > >>>>>> --- > >>>>>> sound/soc/soc-pcm.c | 1 - > >>>>>> 1 files changed, 0 insertions(+), 1 deletions(-) > >>>>>> > >>>>>> diff --git a/sound/soc/soc-pcm.c b/sound/soc/soc-pcm.c > >>>>>> index 891b9a9..ec07e37 100644 > >>>>>> --- a/sound/soc/soc-pcm.c > >>>>>> +++ b/sound/soc/soc-pcm.c > >>>>>> @@ -1339,7 +1339,6 @@ static int dpcm_be_dai_hw_params(struct snd_soc_pcm_runtime *fe, int stream) > >>>>>> continue; > >>>>>> > >>>>>> if ((be->dpcm[stream].state != SND_SOC_DPCM_STATE_OPEN) && > >>>>>> - (be->dpcm[stream].state != SND_SOC_DPCM_STATE_HW_PARAMS) && > >>>>>> (be->dpcm[stream].state != SND_SOC_DPCM_STATE_HW_FREE)) > >>>>>> continue; > >>>>>> > >>>>>> -- > >>>>>> 1.7.0.4 > >>>>>> > >>>>>> _______________________________________________ > >>>>>> Alsa-devel mailing list > >>>>>> Alsa-devel@alsa-project.org > >>>>>> http://mailman.alsa-project.org/mailman/listinfo/alsa-devel > >>>>>> > >>>> > >>> > >>> > >>> > >> > > _______________________________________________ > Alsa-devel mailing list > Alsa-devel@alsa-project.org > http://mailman.alsa-project.org/mailman/listinfo/alsa-devel > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/