Re: [PATCH 4/4] soc: imx: imx8m-blk-ctrl: Scan subnodes and bind drivers to them

[Liu Ying <victor.liu@nxp.com>]

Hi Marek,

On Sun, 2023-02-19 at 00:54 +0100, Marek Vasut wrote:
> This particular block can have DT subnodes describing the LVDS LDB
> bridge. Instead of misusing simple-bus to scan for those nodes, do
> the scan within the driver.
> 
> Fixes: 94e6197dadc9 ("arm64: dts: imx8mp: Add LCDIF2 & LDB nodes")
> Signed-off-by: Marek Vasut <marex@denx.de>
> ---
> Cc: Alexander Stein <alexander.stein@ew.tq-group.com>
> Cc: Fabio Estevam <festevam@gmail.com>
> Cc: Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>
> Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
> Cc: Lucas Stach <l.stach@pengutronix.de>
> Cc: NXP Linux Team <linux-imx@nxp.com>
> Cc: Paul Elder <paul.elder@ideasonboard.com>
> Cc: Peng Fan <peng.fan@nxp.com>
> Cc: Pengutronix Kernel Team <kernel@pengutronix.de>
> Cc: Richard Cochran <richardcochran@gmail.com>
> Cc: Richard Zhu <hongxing.zhu@nxp.com>
> Cc: Rob Herring <robh+dt@kernel.org>
> Cc: Sascha Hauer <s.hauer@pengutronix.de>
> Cc: Shawn Guo <shawnguo@kernel.org>
> Cc: devicetree@vger.kernel.org
> Cc: linux-arm-kernel@lists.infradead.org
> ---
>  drivers/soc/imx/imx8m-blk-ctrl.c | 11 +++++++++++
>  1 file changed, 11 insertions(+)
> 
> diff --git a/drivers/soc/imx/imx8m-blk-ctrl.c
> b/drivers/soc/imx/imx8m-blk-ctrl.c
> index 399cb85105a18..ab48f9dff4be5 100644
> --- a/drivers/soc/imx/imx8m-blk-ctrl.c
> +++ b/drivers/soc/imx/imx8m-blk-ctrl.c
> @@ -169,7 +169,9 @@ static int imx8m_blk_ctrl_probe(struct
> platform_device *pdev)
>  {
>  	const struct imx8m_blk_ctrl_data *bc_data;
>  	struct device *dev = &pdev->dev;
> +	struct platform_device *child;
>  	struct imx8m_blk_ctrl *bc;
> +	struct device_node *np;
>  	void __iomem *base;
>  	int i, ret;
>  
> @@ -310,6 +312,15 @@ static int imx8m_blk_ctrl_probe(struct
> platform_device *pdev)
>  
>  	dev_set_drvdata(dev, bc);

nit: I would put the below loop before dev_set_drvdata().

>  
> +	for_each_child_of_node(dev->of_node, np) {

Please call for_each_available_child_of_node() to create available
child devices only.

> +		child = of_platform_device_create(np, NULL, dev);
> +		if (!child)
> +			ret = -ENOMEM;

-ENODEV is more appropriate?

> +		of_node_put(np);

for_each_child_of_node() and for_each_available_child_node() would do
of_node_put() for you unless you break/return from the loop.

> +		if (ret)
> +			goto cleanup_provider;

Instead of return in case of creating child device failure, I would
give a warning message and continue to create other child devices if
any. So I would write:

-------------------------------8<-----------------------------------
        for_each_available_child_of_node(dev->of_node, np) {
                child = of_platform_device_create(np, NULL, dev);
                if (!child)
                        dev_warn(dev, "failed to create device for
%pOF\n", child);
        }
-------------------------------8<-----------------------------------

Even if return is used, dev_pm_genpd_remove_notifier() should be called
to bailout correctly.

Regards,
Liu Ying

> +	}
> +
>  	return 0;
>  
>  cleanup_provider: