linux-kernel - Re: [PATCH] ASoC: fsl-asoc-card: Remove fsl_asoc_card_set_bias

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Date:   Sun, 26 Jul 2020 17:55:59 -0700
From:   Nicolin Chen <nicoleotsuka@...il.com>
To:     Shengjiu Wang <shengjiu.wang@....com>
Cc:     timur@...nel.org, Xiubo.Lee@...il.com, festevam@...il.com,
        lgirdwood@...il.com, broonie@...nel.org, perex@...ex.cz,
        tiwai@...e.com, alsa-devel@...a-project.org,
        linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] ASoC: fsl-asoc-card: Remove fsl_asoc_card_set_bias_level
 function

On Sun, Jul 26, 2020 at 07:20:17PM +0800, Shengjiu Wang wrote:
> With this case:
> aplay -Dhw:x 16khz.wav 24khz.wav
> There is sound distortion for 24khz.wav. The reason is that setting
> PLL of WM8962 with set_bias_level function, the bias level is not
> changed when 24khz.wav is played, then the PLL won't be reset, the
> clock is not correct, so distortion happens.
> 
> The resolution of this issue is to remove fsl_asoc_card_set_bias_level.
> Move PLL configuration to hw_params and hw_free.

Hmm...using set_bias_level() instead of hw_params/hw_free() was
strongly suggested by Mark when I got imx-wm8962 machine driver
upstream. So we will need his input here, although I personally
don't have a problem with it...

> After removing fsl_asoc_card_set_bias_level, also test WM8960 case,
> it can work.
> 
> Fixes: 708b4351f08c ("ASoC: fsl: Add Freescale Generic ASoC Sound Card with ASRC support")
> Signed-off-by: Shengjiu Wang <shengjiu.wang@....com>
> ---
>  sound/soc/fsl/fsl-asoc-card.c | 149 +++++++++++++++-------------------
>  1 file changed, 66 insertions(+), 83 deletions(-)
> 
> diff --git a/sound/soc/fsl/fsl-asoc-card.c b/sound/soc/fsl/fsl-asoc-card.c
> index 4848ba61d083..0517dbb3e908 100644
> --- a/sound/soc/fsl/fsl-asoc-card.c
> +++ b/sound/soc/fsl/fsl-asoc-card.c
> @@ -73,6 +73,7 @@ struct cpu_priv {
>   * @codec_priv: CODEC private data
>   * @cpu_priv: CPU private data
>   * @card: ASoC card structure
> + * @is_stream_in_use: flags for release resource in hw_free

Would love to see something shorter... Could we reuse similar
one below, borrowing from fsl_ssi driver?

 * @streams: Mask of current active streams: BIT(TX) and BIT(RX)

>  static int fsl_asoc_card_audmux_init(struct device_node *np,
>  				     struct fsl_asoc_card_priv *priv)
>  {
> @@ -611,7 +600,6 @@ static int fsl_asoc_card_probe(struct platform_device *pdev)
>  	/* Diversify the card configurations */
>  	if (of_device_is_compatible(np, "fsl,imx-audio-cs42888")) {
>  		codec_dai_name = "cs42888";
> -		priv->card.set_bias_level = NULL;

Can check if set_bias_level is still being used with this change.