linux-kernel - Re: [PATCH 2/2] ASoC: fsl_spdif: Add support for imx6sx platform

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Message-ID: <20200616232810.GA19896@Asurada-Nvidia>
Date:   Tue, 16 Jun 2020 16:28:11 -0700
From:   Nicolin Chen <nicoleotsuka@...il.com>
To:     Shengjiu Wang <shengjiu.wang@....com>
Cc:     timur@...nel.org, Xiubo.Lee@...il.com, festevam@...il.com,
        broonie@...nel.org, perex@...ex.cz, tiwai@...e.com,
        alsa-devel@...a-project.org, lgirdwood@...il.com,
        robh+dt@...nel.org, devicetree@...r.kernel.org,
        linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/2] ASoC: fsl_spdif: Add support for imx6sx platform

On Tue, Jun 16, 2020 at 02:42:41PM +0800, Shengjiu Wang wrote:
> The one difference on imx6sx platform is that the root clock
> is shared with ASRC module, so we add a new flags "ind_root_clk"
> which means the root clock is independent, then we will not
> do the clk_set_rate and clk_round_rate to avoid impact ASRC
> module usage.
> 
> As add a new flags, we include the soc specific data struct.
> 
> Signed-off-by: Shengjiu Wang <shengjiu.wang@....com>
> ---
>  sound/soc/fsl/fsl_spdif.c | 43 +++++++++++++++++++++++++++++++++++----
>  1 file changed, 39 insertions(+), 4 deletions(-)
> 
> diff --git a/sound/soc/fsl/fsl_spdif.c b/sound/soc/fsl/fsl_spdif.c
> index 1b2e516f9162..00e06803d32f 100644
> --- a/sound/soc/fsl/fsl_spdif.c
> +++ b/sound/soc/fsl/fsl_spdif.c
> @@ -42,6 +42,17 @@ static u8 srpc_dpll_locked[] = { 0x0, 0x1, 0x2, 0x3, 0x4, 0xa, 0xb };
>  
>  #define DEFAULT_RXCLK_SRC	1
>  
> +/**
> + * struct fsl_spdif_soc_data: soc specific data
> + *
> + * @imx: for imx platform
> + * @ind_root_clk: flag for round clk rate
> + */
> +struct fsl_spdif_soc_data {
> +	bool imx;
> +	bool ind_root_clk;

"ind" doesn't look very straightforward; maybe "shared_root_clock"?

And for its comments:
	* @shared_root_clock: flag of sharing a clock source with others;
	*		      so the driver shouldn't set root clock rate

> +};
> +
>  /*
>   * SPDIF control structure
>   * Defines channel status, subcode and Q sub
> @@ -93,6 +104,7 @@ struct fsl_spdif_priv {
>  	struct snd_soc_dai_driver cpu_dai_drv;
>  	struct platform_device *pdev;
>  	struct regmap *regmap;
> +	const struct fsl_spdif_soc_data *soc;

Looks better if we move it to the top of the list :)

> @@ -421,7 +448,7 @@ static int spdif_set_sample_rate(struct snd_pcm_substream *substream,
>  	sysclk_df = spdif_priv->sysclk_df[rate];
>  
>  	/* Don't mess up the clocks from other modules */
> -	if (clk != STC_TXCLK_SPDIF_ROOT)
> +	if (clk != STC_TXCLK_SPDIF_ROOT || !spdif_priv->soc->ind_root_clk)
>  		goto clk_set_bypass;
>  
>  	/* The S/PDIF block needs a clock of 64 * fs * txclk_df */
> @@ -1186,7 +1213,8 @@ static int fsl_spdif_probe_txclk(struct fsl_spdif_priv *spdif_priv,
>  			continue;
>  
>  		ret = fsl_spdif_txclk_caldiv(spdif_priv, clk, savesub, index,
> -					     i == STC_TXCLK_SPDIF_ROOT);
> +					     i == STC_TXCLK_SPDIF_ROOT &&
> +					     spdif_priv->soc->ind_root_clk);

Having more than one place that checks the condition, we can add:

/* Check if clk is a root clock that does not share clock source with others */
static inline bool fsl_spdif_can_set_clk_rate(struct fsl_spdif_priv *spdif, int clk)
{
	return (clk == STC_TXCLK_SPDIF_ROOT) && !spdif->soc->shared_root_clock;
}