linux-kernel - Re: [alsa-devel] [PATCH] ASoC: dpcm: don't do hw_param when BE has done hw_param

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Date:	Fri, 10 Jan 2014 19:21:34 +0800
From:	Nenghua Cao <nhcao@...vell.com>
To:	Takashi Iwai <tiwai@...e.de>
CC:	Liam Girdwood <liam.r.girdwood@...ux.intel.com>,
	Mark Brown <broonie@...nel.org>,
	Jaroslav Kysela <perex@...ex.cz>,
	"alsa-devel@...a-project.org" <alsa-devel@...a-project.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [alsa-devel] [PATCH] ASoC: dpcm: don't do hw_param when BE has
 done	hw_param

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 <nhcao@...vell.com>
>>
>>     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...)
> 
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.
> 
> Takashi
> 
>>
>> Signed-off-by: Nenghua Cao <nhcao@...vell.com>
>> ---
>>  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@...a-project.org
>> http://mailman.alsa-project.org/mailman/listinfo/alsa-devel
>>

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