linux-kernel - Re: [alsa-devel] [PATCH v3 2/2] ASoC: imx-wm8962: Fix codec

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Date:   Tue, 28 Mar 2017 12:53:06 +0100
From:   Charles Keepax <ckeepax@...nsource.wolfsonmicro.com>
To:     Daniel Baluta <daniel.baluta@...il.com>
CC:     Daniel Baluta <daniel.baluta@....com>,
        Nicolin Chen <nicoleotsuka@...il.com>,
        Mark Brown <broonie@...nel.org>, <alsa-devel@...a-project.org>,
        Timur Tabi <timur@...i.org>, <Xiubo.Lee@...il.com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Liam Girdwood <lgirdwood@...il.com>,
        Takashi Iwai <tiwai@...e.com>, <fabio.estevam@....com>,
        <linuxppc-dev@...ts.ozlabs.org>
Subject: Re: [alsa-devel] [PATCH v3 2/2] ASoC: imx-wm8962: Fix codec_clk
 cleanup

On Tue, Mar 28, 2017 at 01:47:04PM +0300, Daniel Baluta wrote:
> On Tue, Mar 28, 2017 at 12:21 PM, Charles Keepax
> <ckeepax@...nsource.wolfsonmicro.com> wrote:
> > On Tue, Mar 28, 2017 at 11:58:52AM +0300, Daniel Baluta wrote:
> >> Resource managed devm_clk_get only works with platform's device dev.
> >>
> >
> > I feel like this could use an explaination of why not using devm
> > is the correct fix, rather than just using the platform device
> > for the call. Its not obvious to me, that using the platform
> > device would be an issue.
> 
> Hi Charles,
> 
> I see where the confusion comes from :) and I thought the explanation
> is obvious from the code, see inline comments.
> 
> Would an explanation like the one below, work better?
> 
> " We cannot use devm_clk_get with &codec_dev->dev device because
> the kernel uses pdev->dev to free the managed resources, so we will end
> up with a leaking codec_clk reference"
> 
> >> @@ -231,7 +231,7 @@ static int imx_wm8962_probe(struct platform_device *pdev)
> >>               goto fail;
> >>       }
> 
> pdev->dev from here:
> 
> >>
> >> -     codec_clk = devm_clk_get(&codec_dev->dev, NULL);
> >> +     codec_clk = clk_get(&codec_dev->dev, NULL);
> 
> is different from &codec_dev->dev.
> 

I get that they are different, I just don't get why changing
from a devm_clk_get to a clk_get is a better fix than changing
&codec->dev to &pdev->dev.

Thanks,
Charles