linux-kernel - Re: [PATCH] ASoC: remove NULL pointer check for clk_disable

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Date:   Sat, 20 May 2017 20:04:03 +0200
From:   Krzysztof Kozlowski <krzk@...nel.org>
To:     Masahiro Yamada <yamada.masahiro@...ionext.com>
Cc:     alsa-devel@...a-project.org, Jaroslav Kysela <perex@...ex.cz>,
        Takashi Iwai <tiwai@...e.com>,
        Fabio Estevam <fabio.estevam@....com>,
        patches@...nsource.wolfsonmicro.com,
        Sangbeom Kim <sbkim73@...sung.com>,
        Sylwester Nawrocki <s.nawrocki@...sung.com>,
        Timur Tabi <timur@...i.org>, Mark Brown <broonie@...nel.org>,
        Support Opensource <support.opensource@...semi.com>,
        linux-kernel@...r.kernel.org, Xiubo Li <Xiubo.Lee@...il.com>,
        Liam Girdwood <lgirdwood@...il.com>,
        Lars-Peter Clausen <lars@...afoo.de>,
        linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org, linuxppc-dev@...ts.ozlabs.org,
        Matthias Brugger <matthias.bgg@...il.com>,
        Nicolin Chen <nicoleotsuka@...il.com>
Subject: Re: [PATCH] ASoC: remove NULL pointer check for clk_disable_unprepare

On Sun, May 21, 2017 at 02:42:38AM +0900, Masahiro Yamada wrote:
> After long term efforts of fixing non-common clock implementations,
> clk_disable() is a no-op for a NULL pointer input, and this is now
> tree-wide consistent.
> 
> All clock consumers can safely call clk_disable(_unprepare) without
> NULL pointer check.
> 
> Signed-off-by: Masahiro Yamada <yamada.masahiro@...ionext.com>
> ---
> 
>  sound/soc/codecs/adau17x1.c                | 3 +--
>  sound/soc/codecs/da7213.c                  | 3 +--
>  sound/soc/codecs/da7218.c                  | 3 +--
>  sound/soc/codecs/da7219-aad.c              | 5 ++---
>  sound/soc/codecs/da7219.c                  | 3 +--
>  sound/soc/codecs/es8328.c                  | 3 +--
>  sound/soc/codecs/wm8731.c                  | 3 +--
>  sound/soc/davinci/davinci-evm.c            | 3 +--
>  sound/soc/fsl/imx-audmux.c                 | 6 ++----
>  sound/soc/intel/boards/bytcr_rt5640.c      | 2 +-
>  sound/soc/intel/boards/cht_bsw_rt5645.c    | 3 +--
>  sound/soc/mediatek/mt8173/mt8173-afe-pcm.c | 6 ++----
>  sound/soc/samsung/i2s.c                    | 3 +--
>  13 files changed, 16 insertions(+), 30 deletions(-)
> 

(...)

> diff --git a/sound/soc/samsung/i2s.c b/sound/soc/samsung/i2s.c
> index af3ba4d..3a06acd 100644
> --- a/sound/soc/samsung/i2s.c
> +++ b/sound/soc/samsung/i2s.c
> @@ -1122,8 +1122,7 @@ static int i2s_runtime_suspend(struct device *dev)
>  	i2s->suspend_i2scon = readl(i2s->addr + I2SCON);
>  	i2s->suspend_i2spsr = readl(i2s->addr + I2SPSR);
>  
> -	if (i2s->op_clk)
> -		clk_disable_unprepare(i2s->op_clk);
> +	clk_disable_unprepare(i2s->op_clk);
>  	clk_disable_unprepare(i2s->clk);

I think the check in i2s_runtime_resume() should be removed then as well
to keep it symmetrical. Otherwise it looks suspicious.

Best regards,
Krzysztof