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

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

On Mon, 2023-02-20 at 10:39 +0800, Liu Ying wrote:
> 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.

Just found that of_platform_device_create() checks if the device node
is available or not, so you may keep using for_each_child_of_node().

Regards,
Liu Ying

> 
> > +		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:
> 
>