linux-kernel - Re: [PATCH] ASoC: codecs: va-macro: use fsgen as clock

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Date:   Wed, 27 Jul 2022 19:08:35 +0530
From:   Srinivasa Rao Mandadapu <quic_srivasam@...cinc.com>
To:     Srinivas Kandagatla <srinivas.kandagatla@...aro.org>,
        <broonie@...nel.org>
CC:     <alsa-devel@...a-project.org>, <lgirdwood@...il.com>,
        <perex@...ex.cz>, <tiwai@...e.com>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] ASoC: codecs: va-macro: use fsgen as clock

Thanks for the Patch Srini!!!

On 7/27/2022 6:17 PM, Srinivas Kandagatla wrote:
> VA Macro fsgen clock is supplied to other LPASS Macros using proper
> clock apis, however the internal user uses the registers directly without
> clk apis. This approch has race condition where in external users of
> the clock might cut the clock while VA macro is actively using this.
>
> Moving the internal usage to clk apis would provide a proper refcounting
> and avoid such race conditions.
>
> This issue was noticed while headset was pulled out while recording is
> in progress and shifting record patch to DMIC.
>
> Reported-by: Srinivasa Rao Mandadapu <quic_srivasam@...cinc.com>
> Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@...aro.org>
> ---
This is verified on SC7280 based platform.

Tested-by: Srinivasa Rao Mandadapu <quic_srivasam@...cinc.com>

>   sound/soc/codecs/lpass-va-macro.c | 11 +++++++++--
>   1 file changed, 9 insertions(+), 2 deletions(-)
>
> diff --git a/sound/soc/codecs/lpass-va-macro.c b/sound/soc/codecs/lpass-va-macro.c
> index d18b56e60433..1ea10dc70748 100644
> --- a/sound/soc/codecs/lpass-va-macro.c
> +++ b/sound/soc/codecs/lpass-va-macro.c
> @@ -199,6 +199,7 @@ struct va_macro {
>   	struct clk *mclk;
>   	struct clk *macro;
>   	struct clk *dcodec;
> +	struct clk *fsgen;
>   	struct clk_hw hw;
>   	struct lpass_macro *pds;
>   
> @@ -467,9 +468,9 @@ static int va_macro_mclk_event(struct snd_soc_dapm_widget *w,
>   
>   	switch (event) {
>   	case SND_SOC_DAPM_PRE_PMU:
> -		return va_macro_mclk_enable(va, true);
> +		return clk_prepare_enable(va->fsgen);
>   	case SND_SOC_DAPM_POST_PMD:
> -		return va_macro_mclk_enable(va, false);
> +		clk_disable_unprepare(va->fsgen);
>   	}
>   
>   	return 0;
> @@ -1473,6 +1474,12 @@ static int va_macro_probe(struct platform_device *pdev)
>   	if (ret)
>   		goto err_clkout;
>   
> +	va->fsgen = clk_hw_get_clk(&va->hw, "fsgen");
> +	if (IS_ERR(va->fsgen)) {
> +		ret = PTR_ERR(va->fsgen);
> +		goto err_clkout;
> +	}
> +
>   	ret = devm_snd_soc_register_component(dev, &va_macro_component_drv,
>   					      va_macro_dais,
>   					      ARRAY_SIZE(va_macro_dais));