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Message-ID: <20241217132222.sfxfknkkl2hvm2v7@pengutronix.de>
Date: Tue, 17 Dec 2024 14:22:22 +0100
From: Marco Felsch <m.felsch@...gutronix.de>
To: Peng Fan <peng.fan@....com>
Cc: "Peng Fan (OSS)" <peng.fan@....nxp.com>,
"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
On 24-12-17, Peng Fan wrote:
> > Subject: Re: [PATCH V2] soc: imx8m: Add remove function
> >
> > 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@....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()
>
> With two devm_add_action, I thought below code would work,
> devm_add_action(dev, soc_device_unregister, (void *)soc_dev);
> devm_add_action(dev, platform_device_unregister, (void *)cpufreq_dev);
Passing the soc_dev and cpufreq_dev as args would remove the
imx8m_soc_priv :)
> But devm_add_action expects: void (*action)(void *),
> So I need introduce two functions to wrap soc_device_unregister,
> and platform_device_unregister.
This is a common pattern.
> This seems not good. Using one devm_add_action just need
> one wrap function, comments?
It's more future proof in case the driver becomes more complex.
Regards,
Marco
>
> Thanks,
> Peng.
>
> >
> > 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@....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
> > > > >
> > > > >
> > > > >
> > >
>
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