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From:   Shengjiu Wang <shengjiu.wang@gmail.com>
Date:   Tue, 9 Feb 2021 17:16:16 +0800
Message-ID: <CAA+D8AMRGRRk6FzdiqaHAP1=dPJngNgmdGmU59vrroXA9BMyXw@mail.gmail.com>
Subject: Re: [PATCH v2 2/7] ASoC: fsl_rpmsg: Add CPU DAI driver for audio base
 on rpmsg
To:     Mark Brown <broonie@kernel.org>
Cc:     Shengjiu Wang <shengjiu.wang@nxp.com>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@vger.kernel.org>, alsa-devel@alsa-project.org,
        Timur Tabi <timur@kernel.org>,
        Liam Girdwood <lgirdwood@gmail.com>,
        linuxppc-dev@lists.ozlabs.org, Xiubo Li <Xiubo.Lee@gmail.com>,
        linux-kernel <linux-kernel@vger.kernel.org>,
        Takashi Iwai <tiwai@suse.com>,
        Nicolin Chen <nicoleotsuka@gmail.com>,
        Rob Herring <robh+dt@kernel.org>,
        Fabio Estevam <festevam@gmail.com>
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On Mon, Feb 8, 2021 at 7:53 PM Mark Brown <broonie@kernel.org> wrote:
>
> On Sun, Feb 07, 2021 at 06:23:50PM +0800, Shengjiu Wang wrote:
>
> > +static int fsl_rpmsg_hw_params(struct snd_pcm_substream *substream,
> > +                            struct snd_pcm_hw_params *params,
> > +                            struct snd_soc_dai *dai)
> > +{
>
> ...
>
> > +     ret = clk_prepare_enable(rpmsg->mclk);
> > +     if (ret)
> > +             dev_err(dai->dev, "failed to enable mclk: %d\n", ret);
> > +
> > +     return ret;
> > +}
> > +
> > +static int fsl_rpmsg_hw_free(struct snd_pcm_substream *substream,
> > +                          struct snd_soc_dai *dai)
> > +{
> > +     struct fsl_rpmsg *rpmsg = snd_soc_dai_get_drvdata(dai);
> > +
> > +     clk_disable_unprepare(rpmsg->mclk);
>
> hw_params() can be called multiple times and there's no need for it to
> be balanced with hw_free(), I'd move this to a different callback (DAPM
> should work well).

Which callback should I use? Is there an example?

best regards
wang shengjiu