linux-kernel - Re: [PATCH v1 1/1] ASoC: rsnd: ssi: Fix issue in dma data address assignment

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Date:   Thu, 21 Dec 2017 18:27:19 -0800
From:   Jiada Wang <jiada_wang@...tor.com>
To:     Kuninori Morimoto <kuninori.morimoto.gx@...esas.com>
CC:     <lgirdwood@...il.com>, <broonie@...nel.org>, <perex@...ex.cz>,
        <tiwai@...e.com>, <alsa-devel@...a-project.org>,
        <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v1 1/1] ASoC: rsnd: ssi: Fix issue in dma data address
 assignment

Hi Morimoto-san

On 12/21/2017 04:43 PM, Kuninori Morimoto wrote:
> Hi Jiada
>
> Thank you for your feedback
> I understand your situation
>
>> We have enabled TDM Split and Ex-Split mode in our kernel,
>> and SSI(U)'s dma address diffs based on the BUSIF it is using,
>> so have a single dma data struct per rsnd_ssi will cause issue when
>> SSI isn't working with BUSIF0.
> First of all, "TDM (Ex) Split mode" is not yet supported.
> And unfortunately, your patch is not enough for it.
> I guess you enabled it with many local patches,
> and posted one of them ?
>
> It is very advanced feature, we need to consider about
> channel/sampling rate/data width/settings/address etc etc etc...
> Lots of things we need to solve/care !
> DMA pointer is one of them.
>
> If we focus only to DMA, your patch is still wrong I think.
> "Playback/Capture direction" is not related to this topic.
> 1 DMA on 1 DAI is enough ?
> And we need to update rsnd_gen2_dma_addr() too for DMA address.
Yes, this patch is only one of a serial patch set to enable TDM (Ex) 
Split mode,
I submitted it alone because think it is independent,
but you are right, to make the background more clear,
I will submit the whole patch set together with this single patch in v2,
(this probably will take some time)

Thanks,
Jiada
>> Do you have any suggestion to address this issue?
> I have no idea at this point.
> Missing part for TDM (Ex) Split mode is not only DMA pointer.
>
> Why do you want to use it ?
> If you want to do is only "use 2 DAIs for playback",
> how about to use MIXer ? It is already supported on upstream.
> Best regards
> ---
> Kuninori Morimoto