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From:   Shengjiu Wang <shengjiu.wang@gmail.com>
Date:   Thu, 3 Dec 2020 11:51:32 +0800
Message-ID: <CAA+D8AOAMV4jyD0uBwER+0KkrBjJcrNPcT4zeYU8Y1WRDRXziQ@mail.gmail.com>
Subject: Re: [PATCH 2/2] ASoC: fsl: Add imx-hdmi machine driver
To:     Nicolin Chen <nicoleotsuka@gmail.com>
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>, Xiubo Li <Xiubo.Lee@gmail.com>,
        Liam Girdwood <lgirdwood@gmail.com>,
        linuxppc-dev@lists.ozlabs.org, Takashi Iwai <tiwai@suse.com>,
        Rob Herring <robh+dt@kernel.org>,
        Mark Brown <broonie@kernel.org>,
        Fabio Estevam <festevam@gmail.com>,
        linux-kernel <linux-kernel@vger.kernel.org>
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On Thu, Dec 3, 2020 at 4:23 AM Nicolin Chen <nicoleotsuka@gmail.com> wrote:
>
> On Fri, Nov 27, 2020 at 01:30:21PM +0800, Shengjiu Wang wrote:
> > The driver is initially designed for sound card using HDMI
> > interface on i.MX platform. There is internal HDMI IP or
> > external HDMI modules connect with SAI or AUD2HTX interface.
> > It supports both transmitter and receiver devices.
> >
> > Signed-off-by: Shengjiu Wang <shengjiu.wang@nxp.com>
> > ---
> >  sound/soc/fsl/Kconfig    |  12 ++
> >  sound/soc/fsl/Makefile   |   2 +
> >  sound/soc/fsl/imx-hdmi.c | 235 +++++++++++++++++++++++++++++++++++++++
> >  3 files changed, 249 insertions(+)
> >  create mode 100644 sound/soc/fsl/imx-hdmi.c
>
> > diff --git a/sound/soc/fsl/imx-hdmi.c b/sound/soc/fsl/imx-hdmi.c
> > new file mode 100644
> > index 000000000000..ac164514b1b2
> > --- /dev/null
> > +++ b/sound/soc/fsl/imx-hdmi.c
>
> > +static int imx_hdmi_hw_params(struct snd_pcm_substream *substream,
> > +                           struct snd_pcm_hw_params *params)
> > +{
> > +     struct snd_soc_pcm_runtime *rtd = substream->private_data;
> > +     struct imx_hdmi_data *data = snd_soc_card_get_drvdata(rtd->card);
> > +     bool tx = substream->stream == SNDRV_PCM_STREAM_PLAYBACK;
> > +     struct snd_soc_dai *cpu_dai = asoc_rtd_to_cpu(rtd, 0);
> > +     struct snd_soc_card *card = rtd->card;
> > +     struct device *dev = card->dev;
> > +     int ret;
> > +
> > +     /* set cpu DAI configuration */
> > +     ret = snd_soc_dai_set_sysclk(cpu_dai, data->cpu_priv.sysclk_id[tx],
> > +                                  8 * data->cpu_priv.slot_width * params_rate(params),
>
> Looks like fixed 2 slots being used, judging by the set_tdm_slot
> call below. Then...why "8 *"? Probably need a line of comments?

The master clock always 256 * rate, when slot_width=32.  so use
the 8 * slot_width.  will add comments.

>
> > +                                  tx ? SND_SOC_CLOCK_OUT : SND_SOC_CLOCK_IN);
> > +     if (ret && ret != -ENOTSUPP) {
> > +             dev_err(dev, "failed to set cpu sysclk: %d\n", ret);
> > +             return ret;
> > +     }
> > +
> > +     ret = snd_soc_dai_set_tdm_slot(cpu_dai, 0, 0, 2, data->cpu_priv.slot_width);
>
> May have a local variable to cache slot_width.

ok.

>
> > +static int imx_hdmi_probe(struct platform_device *pdev)
>
> > +     data->dai.name = "i.MX HDMI";
> > +     data->dai.stream_name = "i.MX HDMI";
> > +     data->dai.cpus->dai_name = dev_name(&cpu_pdev->dev);
> > +     data->dai.platforms->of_node = cpu_np;
> > +     data->dai.ops = &imx_hdmi_ops;
> > +     data->dai.playback_only = true;
> > +     data->dai.capture_only = false;
> > +     data->dai.init = imx_hdmi_init;
> > +
> > +
> > +     if (of_property_read_bool(np, "hdmi-out")) {
> > +             data->dai.playback_only = true;
> > +             data->dai.capture_only = false;
> > +             data->dai.codecs->dai_name = "i2s-hifi";
> > +             data->dai.codecs->name = "hdmi-audio-codec.1";
> > +             data->dai.dai_fmt = data->dai_fmt |
> > +                                 SND_SOC_DAIFMT_NB_NF |
> > +                                 SND_SOC_DAIFMT_CBS_CFS;
> > +     }
> > +
> > +     if (of_property_read_bool(np, "hdmi-in")) {
> > +             data->dai.playback_only = false;
> > +             data->dai.capture_only = true;
> > +             data->dai.codecs->dai_name = "i2s-hifi";
> > +             data->dai.codecs->name = "hdmi-audio-codec.2";
> > +             data->dai.dai_fmt = data->dai_fmt |
> > +                                 SND_SOC_DAIFMT_NB_NF |
> > +                                 SND_SOC_DAIFMT_CBM_CFM;
> > +     }
> > +
> > +     if ((data->dai.playback_only && data->dai.capture_only) ||
> > +         (!data->dai.playback_only && !data->dai.capture_only)) {
> > +             dev_err(&pdev->dev, "Wrongly enable HDMI DAI link\n");
> > +             goto fail;
> > +     }
>
> Seems that this condition check can never be true, given that:
> 1. By default: playback_only=true && capture_only=false
> 2. Conditionally overwritten: playback_only=true && capture_only=false
> 3. Conditionally overwritten: playback_only=false && capture_only=true
>
> If I understand it correctly, probably should be something like:
>         bool hdmi_out = of_property_read_bool(np, "hdmi-out");
>         bool hdmi_in = of_property_read_bool(np, "hdmi-in");
>
>         if ((hdmi_out && hdmi_in) || (!hdmi_out || !hdmi_in))
>                 // "Invalid HDMI DAI link"; goto fail;
>
>         if (hdmi_out) {
>                 // ...
>         } else if (hdmi_in) {
>                 // ...
>         } else // No need of this line if two properties are exclusive
>

Good catch, will update it.

> > +     data->card.num_links = 1;
> > +     data->card.dai_link = &data->dai;
> > +
> > +     platform_set_drvdata(pdev, &data->card);
>
> Why pass card pointer?

Seems it duplicates with dev_set_drvdata(card->dev, card);
in snd_soc_register_card.  will remove it.

best regards
wang shengjiu