On 22/02/2019 23:27, Russell King wrote:
> Some HDMI codecs need to know the relationship between the I2S bit clock
> and the I2S word clock in order to correctly generate the CTS value for
> audio clock recovery on the sink.
>
> Add support for this, but there are currently no callers of
> snd_soc_dai_set_bclk_ratio(), we provide a default implementation that
> uses the sample width to derive the ratio from the 8-bit aligned
> sample size. This reflects the derivation that is in TDA998x, which
> we are going to convert to use this new support.
>
> Signed-off-by: Russell King <rmk+kernel@xxxxxxxxxxxxxxx>
> ---
> include/sound/hdmi-codec.h | 1 +
> sound/soc/codecs/hdmi-codec.c | 45 +++++++++++++++++++++++++++++++++++++++++--
> 2 files changed, 44 insertions(+), 2 deletions(-)
>
> diff --git a/include/sound/hdmi-codec.h b/include/sound/hdmi-codec.h
> index 9483c55f871b..0fca69880dc3 100644
> --- a/include/sound/hdmi-codec.h
> +++ b/include/sound/hdmi-codec.h
> @@ -42,6 +42,7 @@ struct hdmi_codec_daifmt {
> unsigned int frame_clk_inv:1;
> unsigned int bit_clk_master:1;
> unsigned int frame_clk_master:1;
> + unsigned int bclk_ratio;
> };
>
> /*
> diff --git a/sound/soc/codecs/hdmi-codec.c b/sound/soc/codecs/hdmi-codec.c
> index e5b6769b9797..d71a7e5a2231 100644
> --- a/sound/soc/codecs/hdmi-codec.c
> +++ b/sound/soc/codecs/hdmi-codec.c
> @@ -470,6 +470,7 @@ static int hdmi_codec_hw_params(struct snd_pcm_substream *substream,
> struct snd_soc_dai *dai)
> {
> struct hdmi_codec_priv *hcp = snd_soc_dai_get_drvdata(dai);
> + struct hdmi_codec_daifmt fmt;
> struct hdmi_codec_params hp = {
> .iec = {
> .status = { 0 },
> @@ -520,8 +521,43 @@ static int hdmi_codec_hw_params(struct snd_pcm_substream *substream,
> hp.sample_rate = params_rate(params);
> hp.channels = params_channels(params);
>
> + fmt = hcp->daifmt[dai->id];
> +
> + /*
> + * If the .set_bclk_ratio() has not been called, default it
> + * using the sample width for compatibility for TDA998x.
> + * Rather than changing this, drivers should arrange to make
> + * an appropriate call to snd_soc_dai_set_bclk_ratio().
> + */
> + if (fmt.bclk_ratio == 0) {
> + switch (hp.sample_width) {
> + case 16:
> + fmt.bclk_ratio = 32;
> + break;
> + case 18:
> + case 20:
> + case 24:
> + fmt.bclk_ratio = 48;
> + break;
AFAIK, this is not the usual choice for 18- or 20-bit samples. Usually,
the bclk_ratio is set to the exact frame length required by the sample
width without any padding. That is at least the case with
tlv320aic3x-driver and 20-bit sample width.
> + default:
> + fmt.bclk_ratio = 64;
> + break;
> + }
> + }
> +
> return hcp->hcd.ops->hw_params(dai->dev->parent, hcp->hcd.data,
> - &hcp->daifmt[dai->id], &hp);
> + &fmt, &hp);
> +}
> +
> +static int hdmi_codec_set_bclk_ratio(struct snd_soc_dai *dai,
> + unsigned int ratio)
> +{
> + struct hdmi_codec_priv *hcp = snd_soc_dai_get_drvdata(dai);
> +
> + /* FIXME: some validation here would be good? */
> + hcp->daifmt[dai->id].bclk_ratio = ratio;
> +
> + return 0;
> }
>
> static int hdmi_codec_set_fmt(struct snd_soc_dai *dai,
> @@ -593,7 +629,11 @@ static int hdmi_codec_set_fmt(struct snd_soc_dai *dai,
> }
> }
>
> - hcp->daifmt[dai->id] = cf;
> + hcp->daifmt[dai->id].fmt = cf.fmt;
> + hcp->daifmt[dai->id].bit_clk_inv = cf.bit_clk_inv;
> + hcp->daifmt[dai->id].frame_clk_inv = cf.frame_clk_inv;
> + hcp->daifmt[dai->id].bit_clk_master = cf.bit_clk_master;
> + hcp->daifmt[dai->id].frame_clk_master = cf.frame_clk_master;
>
> return ret;
> }
> @@ -615,6 +655,7 @@ static const struct snd_soc_dai_ops hdmi_dai_ops = {
> .startup = hdmi_codec_startup,
> .shutdown = hdmi_codec_shutdown,
> .hw_params = hdmi_codec_hw_params,
> + .set_bclk_ratio = hdmi_codec_set_bclk_ratio,
> .set_fmt = hdmi_codec_set_fmt,
> .digital_mute = hdmi_codec_digital_mute,
> };
>
--
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