linux-kernel - Re: [PATCH v2 3/7] soc: qcom: add QCOM PBS driver

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Date:   Mon, 31 Jul 2023 12:22:29 -0700
From:   Bjorn Andersson <quic_bjorande@...cinc.com>
To:     Konrad Dybcio <konrad.dybcio@...aro.org>
CC:     Anjelique Melendez <quic_amelende@...cinc.com>, <pavel@....cz>,
        <lee@...nel.org>, <thierry.reding@...il.com>, <robh+dt@...nel.org>,
        <krzysztof.kozlowski+dt@...aro.org>, <conor+dt@...nel.org>,
        <agross@...nel.org>, <andersson@...nel.org>,
        <luca.weiss@...rphone.com>, <u.kleine-koenig@...gutronix.de>,
        <quic_subbaram@...cinc.com>, <linux-leds@...r.kernel.org>,
        <devicetree@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <linux-arm-msm@...r.kernel.org>, <linux-pwm@...r.kernel.org>
Subject: Re: [PATCH v2 3/7] soc: qcom: add QCOM PBS driver

On Wed, Jul 26, 2023 at 05:36:08PM +0200, Konrad Dybcio wrote:
> On 25.07.2023 21:34, Anjelique Melendez wrote:
> > +struct pbs_dev *get_pbs_client_device(struct device *dev)
> > +{
> > +	struct device_node *pbs_dev_node;
> > +	struct platform_device *pdev;
> > +	struct pbs_dev *pbs;
> > +
> > +	pbs_dev_node = of_parse_phandle(dev->of_node, "qcom,pbs", 0);
> > +	if (!pbs_dev_node) {
> > +		dev_err(dev, "Missing qcom,pbs property\n");
> > +		return ERR_PTR(-ENODEV);
> > +	}
> > +
> > +	pdev = of_find_device_by_node(pbs_dev_node);
> > +	if (!pdev) {
> > +		dev_err(dev, "Unable to find PBS dev_node\n");
> > +		pbs = ERR_PTR(-EPROBE_DEFER);
> > +		goto out;
> > +	}
> > +
> > +	pbs = platform_get_drvdata(pdev);
> > +	if (!pbs) {
> This check seems unnecessary, the PBS driver would have had to fail
> probing if set_drvdata never got called.
> 

That's not necessarily the case, the platform_device will exist before
the probe function has been invoked. So checking this sounds
appropriate.

But if we have a valid link, but no drvdata, perhaps it would be more
appropriate to return -EPROBE_DEFER?

Regards,
Bjorn