linux-kernel - RE: [PATCH] ASoC: amd :High hw_level while simultaneous capture

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Message-ID: <CY4PR12MB182949DC53DCCCDAC02112E7E7A70@CY4PR12MB1829.namprd12.prod.outlook.com>
Date:   Tue, 5 May 2020 12:18:45 +0000
From:   "RAVULAPATI, VISHNU VARDHAN RAO" 
        <Vishnuvardhanrao.Ravulapati@....com>
To:     Mark Brown <broonie@...nel.org>,
        "Agrawal, Akshu" <Akshu.Agrawal@....com>
CC:     Liam Girdwood <lgirdwood@...il.com>,
        Jaroslav Kysela <perex@...ex.cz>,
        Takashi Iwai <tiwai@...e.com>,
        "Mukunda, Vijendar" <Vijendar.Mukunda@....com>,
        Colin Ian King <colin.king@...onical.com>,
        Kuninori Morimoto <kuninori.morimoto.gx@...esas.com>,
        "moderated list:SOUND - SOC LAYER / DYNAMIC AUDIO POWER MANAGEM..." 
        <alsa-devel@...a-project.org>,
        open list <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH] ASoC: amd :High hw_level while simultaneous capture

[AMD Official Use Only - Internal Distribution Only]

-----Original Message-----
From: Mark Brown <broonie@...nel.org>
Sent: Tuesday, May 5, 2020 5:21 PM
To: Agrawal, Akshu <Akshu.Agrawal@....com>
Cc: RAVULAPATI, VISHNU VARDHAN RAO <Vishnuvardhanrao.Ravulapati@....com>; Liam Girdwood <lgirdwood@...il.com>; Jaroslav Kysela <perex@...ex.cz>; Takashi Iwai <tiwai@...e.com>; Mukunda, Vijendar <Vijendar.Mukunda@....com>; Colin Ian King <colin.king@...onical.com>; Kuninori Morimoto <kuninori.morimoto.gx@...esas.com>; moderated list:SOUND - SOC LAYER / DYNAMIC AUDIO POWER MANAGEM... <alsa-devel@...a-project.org>; open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] ASoC: amd :High hw_level while simultaneous capture

On Tue, May 05, 2020 at 05:10:20PM +0530, Akshu Agrawal wrote:

> Simultaneous capture on dmic and headset mic is having issue with high 
> hw_level being reported.

> Issue Can be reproduced by:
> arecord -D hw:2,0 -f dat -d 60 /tmp/test0 & arecord -D hw:2,2 -f dat 
> -d 60 /tmp/test1 & cat /proc/asound/card2/pcm?c/sub0/status

What is a "high hw_level" and how does this patch address it?  As far as I can see this patch reorders some of the initialzation but it's not entirely obvious what the issue was or how this fixes it.

Actual issue is :
When we open one capture stream on one instance lets say I2S_SP and then once again if we open other capture on other instance lets say I2S_BT while first capture is in progress and when we try to read the status of both running instances by below command cat /proc/asound/card2/pcm?c/sub0/status
we observe that avail_max is being doubled on first opened capture(I2S_SP in the example).

This is because our previous implementation was like when any instance is opened it gets initialized in dma_open irrespective of on what instance it called open.
For example:
First I2S_SP called opened it initializes both SP/BT capture streams irrespective of on which instance the stream opened.next time I2S_BT called opened and it initializes both SP/BT this corrupts the behaviour .

So with this patch the stream gets initialized only on specific instance when ever it gets opened calls hw_params.

This rectifies the issue.

Thanks,
Vishnu