Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
Date:   30 Jun 2020 09:56:17 +0900
Message-ID: <87o8p1z81b.wl-kuninori.morimoto.gx@renesas.com>
From:   Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
To:     Sameer Pujar <spujar@nvidia.com>
Cc:     <broonie@kernel.org>, <perex@perex.cz>, <tiwai@suse.com>,
        <robh+dt@kernel.org>, <lgirdwood@gmail.com>,
        <thierry.reding@gmail.com>, <jonathanh@nvidia.com>,
        <digetx@gmail.com>, <alsa-devel@alsa-project.org>,
        <linux-tegra@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
        <sharadg@nvidia.com>, <mkumard@nvidia.com>,
        <viswanathl@nvidia.com>, <rlokhande@nvidia.com>,
        <dramesh@nvidia.com>, <atalambedu@nvidia.com>,
        <nwartikar@nvidia.com>, <swarren@nvidia.com>,
        <nicoleotsuka@gmail.com>
Subject: Re: [PATCH v4 10/23] ASoC: simple-card: Wrong daifmt for CPU end of DPCM DAI link
In-Reply-To: <6e27daa5-331e-968b-4027-2e30aeb7d382@nvidia.com>
References: <1593233625-14961-1-git-send-email-spujar@nvidia.com>
        <1593233625-14961-11-git-send-email-spujar@nvidia.com>
        <877dvq1yhy.wl-kuninori.morimoto.gx@renesas.com>
        <6e27daa5-331e-968b-4027-2e30aeb7d382@nvidia.com>
User-Agent: Wanderlust/2.15.9 Emacs/26.3 Mule/6.0
MIME-Version: 1.0 (generated by SEMI-EPG 1.14.7 - "Harue")
Content-Type: text/plain; charset=US-ASCII
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk


Hi Sameer

>  snd_soc_runtime_set_dai_fmt() {
>      ...
> 
>      if (cpu_dai->component->driver->non_legacy_dai_naming)
>          fmt = inv_dai_fmt;
> 
>      ...
>  }
> 
> Above flips polarity for 'cpu_dai' if 'non_legacy_dai_naming' flag is set.
> 
> 1. Hence example mentioned in the commit message does not work if my 'cpu_dai'
> driver does not have this flag set.

?
Do you want fo flip it ? or don't flip?
It is for Codec <-> Codec connection.

> 2. While it is true that we consider reference of 'Codec' mode for simple CPU<->
> Codec DAI links, for DPCM this does not seem flexible. For DPCM links CPU and
> Codec are not directly connected (CPU<->Dummy or Dummy<->Codec). Please
> consider, for example, if the DAI link has multiple CPU/Codecs. Which 'Codec'
> reference needs to be considered? Isn't it better if we explicitly mention which
> DAI we want to operate as 'Master'?

I think Lars-Peter has (had ?) plan for this SND_SOC_DAIFMT_CBx_CFx
flag flexibility ? Yes maybe it is needed for multi CPU/Codec system.

Thank you for your help !!

Best regards
---
Kuninori Morimoto