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From:   Daniel Baluta <daniel.baluta@gmail.com>
Date:   Wed, 11 Sep 2019 16:06:41 +0300
Message-ID: <CAEnQRZAid2xXu+6PxWDCBNDwS6c8DfNXEcNqseDPAsVJ7kEHeg@mail.gmail.com>
Subject: Re: [alsa-devel] [PATCH] ASoC: fsl_sai: Implement set_bclk_ratio
To:     Mark Brown <broonie@kernel.org>
Cc:     Nicolin Chen <nicoleotsuka@gmail.com>,
        Linux-ALSA <alsa-devel@alsa-project.org>,
        Timur Tabi <timur@kernel.org>, Xiubo Li <Xiubo.Lee@gmail.com>,
        Daniel Baluta <daniel.baluta@nxp.com>,
        "S.j. Wang" <shengjiu.wang@nxp.com>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        NXP Linux Team <linux-imx@nxp.com>,
        Viorel Suman <viorel.suman@nxp.com>,
        Fabio Estevam <festevam@gmail.com>
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On Wed, Sep 11, 2019 at 2:01 PM Mark Brown <broonie@kernel.org> wrote:
>
> On Thu, Sep 05, 2019 at 06:29:39PM -0700, Nicolin Chen wrote:
> > On Sat, Aug 31, 2019 at 12:59:10AM +0300, Daniel Baluta wrote:
>
> > > This is to allow machine drivers to set a certain bitclk rate
> > > which might not be exactly rate * frame size.
>
> > Just a quick thought of mine: slot_width and slots could be
> > set via set_dai_tdm_slot() actually, while set_bclk_ratio()
> > would override that one with your change. I'm not sure which
> > one could be more important...so would you mind elaborating
> > your use case?
>
> The reason we have both operations is partly that some hardware
> can configure the ratio but not do TDM and partly that setting
> TDM slots forces us to configure the slot size depending on the
> current stream configuration while just setting the ratio means
> we can just fix the configuration once.  I'd say it's just a user
> error to try to do both simultaneously.

Yes, exactly. We wanted to have a better control of bclk freq.
Sorry for the late answer, I'm traveling.