Re: [PATCH 1/7] slimbus: qcom-ngd-ctrl: Fix up platform_driver registration

[Mukesh Ojha]

On Mon, Mar 09, 2026 at 11:09:02PM -0500, Bjorn Andersson wrote:
> Device drivers should not invoke platform_driver_register()/unregister()
> in their probe and remove paths. They should further not rely on
> platform_driver_unregister() as their only means of "deleting" their
> child devices.
> 
> Introduce a helper to unregister the child device and move the
> platform_driver_register()/unregister() to module_init()/exit().
> 
> Fixes: 917809e2280b ("slimbus: ngd: Add qcom SLIMBus NGD driver")
> Cc: stable@xxxxxxxxxxxxxxx
> Signed-off-by: Bjorn Andersson <bjorn.andersson@xxxxxxxxxxxxxxxx>

Reviewed-by: Mukesh Ojha <mukesh.ojha@xxxxxxxxxxxxxxxx>

> ---
>  drivers/slimbus/qcom-ngd-ctrl.c | 36 +++++++++++++++++++++++++++++++++---
>  1 file changed, 33 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/slimbus/qcom-ngd-ctrl.c b/drivers/slimbus/qcom-ngd-ctrl.c
> index 9aa7218b4e8d2b350835626839371ed6e19860e2..c69656a0ef1766d5a9df40bdf37bae8f64789fab 100644
> --- a/drivers/slimbus/qcom-ngd-ctrl.c
> +++ b/drivers/slimbus/qcom-ngd-ctrl.c
> @@ -1562,6 +1562,13 @@ static int of_qcom_slim_ngd_register(struct device *parent,
>  	return -ENODEV;
>  }
>  
> +static void qcom_slim_ngd_unregister(struct qcom_slim_ngd_ctrl *ctrl)
> +{
> +	struct qcom_slim_ngd *ngd = ctrl->ngd;
> +
> +	platform_device_del(ngd->pdev);

First, it surprised me why only once, then I saw there is return 0 in
for_each_available_child_of_node_scoped() loop..

> +}
> +
>  static int qcom_slim_ngd_probe(struct platform_device *pdev)
>  {
>  	struct device *dev = &pdev->dev;
> @@ -1664,7 +1671,6 @@ static int qcom_slim_ngd_ctrl_probe(struct platform_device *pdev)
>  		goto err_pdr_lookup;
>  	}
>  
> -	platform_driver_register(&qcom_slim_ngd_driver);
>  	return of_qcom_slim_ngd_register(dev, ctrl);
>  
>  err_pdr_alloc:
> @@ -1678,7 +1684,9 @@ static int qcom_slim_ngd_ctrl_probe(struct platform_device *pdev)
>  
>  static void qcom_slim_ngd_ctrl_remove(struct platform_device *pdev)
>  {
> -	platform_driver_unregister(&qcom_slim_ngd_driver);
> +	struct qcom_slim_ngd_ctrl *ctrl = platform_get_drvdata(pdev);
> +
> +	qcom_slim_ngd_unregister(ctrl);
>  }
>  
>  static void qcom_slim_ngd_remove(struct platform_device *pdev)
> @@ -1754,6 +1762,28 @@ static struct platform_driver qcom_slim_ngd_driver = {
>  	},
>  };
>  
> -module_platform_driver(qcom_slim_ngd_ctrl_driver);
> +static int qcom_slim_ngd_init(void)
> +{
> +	int ret;
> +
> +	ret = platform_driver_register(&qcom_slim_ngd_ctrl_driver);
> +	if (ret)
> +		return ret;
> +
> +	ret = platform_driver_register(&qcom_slim_ngd_driver);
> +	if (ret)
> +		platform_driver_unregister(&qcom_slim_ngd_ctrl_driver);
> +
> +	return ret;
> +}
> +
> +static void qcom_slim_ngd_exit(void)
> +{
> +	platform_driver_unregister(&qcom_slim_ngd_driver);
> +	platform_driver_unregister(&qcom_slim_ngd_ctrl_driver);
> +}
> +
> +module_init(qcom_slim_ngd_init);
> +module_exit(qcom_slim_ngd_exit);
>  MODULE_LICENSE("GPL v2");
>  MODULE_DESCRIPTION("Qualcomm SLIMBus NGD controller");
> 
> -- 
> 2.51.0
> 

-- 
-Mukesh Ojha