linux-kernel - Re: [PATCH] ASoC: amd: Buffer Size instead of MAX Buffer

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Date:   Wed, 12 Feb 2020 14:36:32 +0530
From:   vishnu <vravulap@....com>
To:     Mark Brown <broonie@...nel.org>,
        Ravulapati Vishnu vardhan rao 
        <Vishnuvardhanrao.Ravulapati@....com>
Cc:     Alexander.Deucher@....com, Liam Girdwood <lgirdwood@...il.com>,
        Jaroslav Kysela <perex@...ex.cz>,
        Takashi Iwai <tiwai@...e.com>,
        Wei Yongjun <weiyongjun1@...wei.com>,
        Akshu Agrawal <akshu.agrawal@....com>,
        Vijendar Mukunda <Vijendar.Mukunda@....com>,
        YueHaibing <yuehaibing@...wei.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: Buffer Size instead of MAX Buffer



On 11/02/20 9:08 PM, Mark Brown wrote:
> On Tue, Feb 11, 2020 at 06:42:28PM +0530, Ravulapati Vishnu vardhan rao wrote:
> 
>> Because of MAX BUFFER size in register,when user/app give small
>> buffer size produces noise of old data in buffer.
>> This patch rectifies this noise when using different
>> buffer sizes less than MAX BUFFER.
> 
> In what way does this patch fix the issue?  I looks like it's moving a
> buffer size setting from DMA to I2S but it's not clear why or how this
> fixes the issue, or indeed what the actual issue that's causing what are
> presumably underruns is?
> 
prior to this fix the value in Tx/Rx Ring Buffer Size register 
ACP_BT_TX_RINGBUFSIZE,ACP_BT_RX_RINGBUFSIZE and same in I2S RINGBUFSIZE 
registers was statically set to maximum which is wrong.
Buffer size must be equal to actual allocated.

Due to which When I play any audio:aplay -Dhw:2,0 test.wav and then stop 
and play  aplay -Dhw:2,0 -c2 -fS16_LE -r48000 /dev/zero 
--buffer-size=2048 I hear some part of old audio.


So after adding above fix the issue is not reproduced.