[PATCH V2] soc: imx8m: Add remove function

[Marco Felsch]

On 24-12-17, Peng Fan wrote:
> > 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 at nxp.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);
> +}

I would split it into two action functions due to the following reasons:
 - cleanup during the probe() if something fails afterwards
 - no need for the if(priv->cpufreq_dev) check.

> In Probe:
> +       return devm_add_action(&pdev->dev, imx8m_soc_remove, priv);

The actions should be added directly after the succeful device
registration, e.g.
 - after soc_device_register(soc_dev_attr) and
 - after platform_device_register_simple()

Regards,
   Marco

> 
> 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 at nxp.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
> > >
> > >
> > >
>