linux-kernel - RE: [PATCH V2] soc: imx8m: Add remove function

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Message-ID:
 <PAXPR04MB8459A91EEC932F41E24AE04488042@PAXPR04MB8459.eurprd04.prod.outlook.com>
Date: Tue, 17 Dec 2024 09:16:43 +0000
From: Peng Fan <peng.fan@....com>
To: Marco Felsch <m.felsch@...gutronix.de>, "Peng Fan (OSS)"
	<peng.fan@....nxp.com>
CC: "shawnguo@...nel.org" <shawnguo@...nel.org>, "s.hauer@...gutronix.de"
	<s.hauer@...gutronix.de>, "marex@...x.de" <marex@...x.de>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"kernel@...gutronix.de" <kernel@...gutronix.de>, "festevam@...il.com"
	<festevam@...il.com>, "linux-arm-kernel@...ts.infradead.org"
	<linux-arm-kernel@...ts.infradead.org>
Subject: RE: [PATCH V2] soc: imx8m: Add remove function

> Subject: Re: [PATCH V2] soc: imx8m: Add remove function
> 
> Hi Peng,
> 
> thanks for you patch.
> 
> On 24-12-17, Peng Fan (OSS) wrote:
> > From: Peng Fan <peng.fan@....com>
> >
> > Unregister the cpufreq device and soc device in remove path,
> otherwise
> 
> After reconsidiering the patch approach, I think we shouldn't add a
> .remove() function and instead should make use of the
> devm_add_action() mechanism for the proper unregister calls.

Would you please share why devm_add_action is preferred?

Something as below?
+static void imx8m_soc_remove(void *data)
+{
+       struct imx8m_soc_priv *priv = data;
+
+       if (priv->cpufreq_dev)
+               platform_device_unregister(priv->cpufreq_dev);
+
+       soc_device_unregister(priv->soc_dev);
+}
+
In Probe:
+       return devm_add_action(&pdev->dev, imx8m_soc_remove, priv);

Regards,
Peng.

> 
> > there will be warning when do removing test:
> > sysfs: cannot create duplicate filename '/devices/platform/imx-
> cpufreq-dt'
> > CPU: 0 UID: 0 PID: 1 Comm: swapper/0 Not tainted
> > 6.13.0-rc1-next-20241204 Hardware name: NXP i.MX8MPlus EVK
> board (DT)
> >
> > Fixes: 9cc832d37799 ("soc: imx8m: Probe the SoC driver as platform
> > driver")
> > Signed-off-by: Peng Fan <peng.fan@....com>
> > ---
> >
> > V2:
> >  Add err check when create the cpufreq platform device
> 
> thank you for addressing this.
> 
> Regards,
>   Marco
> 
> >  drivers/soc/imx/soc-imx8m.c | 41
> > +++++++++++++++++++++++++++++++------
> >  1 file changed, 35 insertions(+), 6 deletions(-)
> >
> > diff --git a/drivers/soc/imx/soc-imx8m.c b/drivers/soc/imx/soc-
> imx8m.c
> > index 8ac7658e3d52..97c8718c2aa1 100644
> > --- a/drivers/soc/imx/soc-imx8m.c
> > +++ b/drivers/soc/imx/soc-imx8m.c
> > @@ -33,6 +33,11 @@ struct imx8_soc_data {
> >  	int (*soc_revision)(u32 *socrev, u64 *socuid);  };
> >
> > +struct imx8m_soc_priv {
> > +	struct soc_device *soc_dev;
> > +	struct platform_device *cpufreq_dev; };
> > +
> >  #ifdef CONFIG_HAVE_ARM_SMCCC
> >  static u32 imx8mq_soc_revision_from_atf(void)
> >  {
> > @@ -195,10 +200,11 @@ static __maybe_unused const struct
> of_device_id
> > imx8_soc_match[] = {  static int imx8m_soc_probe(struct
> > platform_device *pdev)  {
> >  	struct soc_device_attribute *soc_dev_attr;
> > +	struct platform_device *cpufreq_dev;
> >  	const struct imx8_soc_data *data;
> >  	struct device *dev = &pdev->dev;
> >  	const struct of_device_id *id;
> > -	struct soc_device *soc_dev;
> > +	struct imx8m_soc_priv *priv;
> >  	u32 soc_rev = 0;
> >  	u64 soc_uid = 0;
> >  	int ret;
> > @@ -207,6 +213,10 @@ static int imx8m_soc_probe(struct
> platform_device *pdev)
> >  	if (!soc_dev_attr)
> >  		return -ENOMEM;
> >
> > +	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
> > +	if (!priv)
> > +		return -ENOMEM;
> > +
> >  	soc_dev_attr->family = "Freescale i.MX";
> >
> >  	ret = of_property_read_string(of_root, "model",
> > &soc_dev_attr->machine); @@ -235,21 +245,40 @@ static int
> imx8m_soc_probe(struct platform_device *pdev)
> >  	if (!soc_dev_attr->serial_number)
> >  		return -ENOMEM;
> >
> > -	soc_dev = soc_device_register(soc_dev_attr);
> > -	if (IS_ERR(soc_dev))
> > -		return PTR_ERR(soc_dev);
> > +	priv->soc_dev = soc_device_register(soc_dev_attr);
> > +	if (IS_ERR(priv->soc_dev))
> > +		return PTR_ERR(priv->soc_dev);
> >
> >  	pr_info("SoC: %s revision %s\n", soc_dev_attr->soc_id,
> >  		soc_dev_attr->revision);
> >
> > -	if (IS_ENABLED(CONFIG_ARM_IMX_CPUFREQ_DT))
> > -		platform_device_register_simple("imx-cpufreq-dt", -1,
> NULL, 0);
> > +	if (IS_ENABLED(CONFIG_ARM_IMX_CPUFREQ_DT)) {
> > +		cpufreq_dev = platform_device_register_simple("imx-
> cpufreq-dt", -1, NULL, 0);
> > +		if (!IS_ERR(cpufreq_dev))
> > +			priv->cpufreq_dev = cpufreq_dev;
> > +		else
> > +			dev_err(dev, "Failed to create imx-cpufreq-
> dev device: %ld",
> > +				PTR_ERR(cpufreq_dev));
> > +	}
> > +
> > +	platform_set_drvdata(pdev, priv);
> >
> >  	return 0;
> >  }
> >
> > +static void imx8m_soc_remove(struct platform_device *pdev) {
> > +	struct imx8m_soc_priv *priv = platform_get_drvdata(pdev);
> > +
> > +	if (priv->cpufreq_dev)
> > +		platform_device_unregister(priv->cpufreq_dev);
> > +
> > +	soc_device_unregister(priv->soc_dev);
> > +}
> > +
> >  static struct platform_driver imx8m_soc_driver = {
> >  	.probe = imx8m_soc_probe,
> > +	.remove	= imx8m_soc_remove,
> >  	.driver = {
> >  		.name = "imx8m-soc",
> >  	},
> > --
> > 2.37.1
> >
> >
> >