linux-kernel - Re: [PATCH v4 4/8] PCI/pwrctrl: Add APIs to power on/off the pwrctrl devices

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Message-ID: <20260112032719.GA695866@bhelgaas>
Date: Sun, 11 Jan 2026 21:27:19 -0600
From: Bjorn Helgaas <helgaas@...nel.org>
To: manivannan.sadhasivam@....qualcomm.com
Cc: Manivannan Sadhasivam <mani@...nel.org>,
	Lorenzo Pieralisi <lpieralisi@...nel.org>,
	Krzysztof Wilczyński <kwilczynski@...nel.org>,
	Rob Herring <robh@...nel.org>, Bjorn Helgaas <bhelgaas@...gle.com>,
	Bartosz Golaszewski <brgl@...ev.pl>, linux-pci@...r.kernel.org,
	linux-arm-msm@...r.kernel.org, linux-kernel@...r.kernel.org,
	Chen-Yu Tsai <wens@...nel.org>,
	Brian Norris <briannorris@...omium.org>,
	Krishna Chaitanya Chundru <krishna.chundru@....qualcomm.com>,
	Niklas Cassel <cassel@...nel.org>, Alex Elder <elder@...cstar.com>,
	Bartosz Golaszewski <bartosz.golaszewski@....qualcomm.com>,
	Chen-Yu Tsai <wenst@...omium.org>,
	Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
Subject: Re: [PATCH v4 4/8] PCI/pwrctrl: Add APIs to power on/off the pwrctrl
 devices

On Mon, Jan 05, 2026 at 07:25:44PM +0530, Manivannan Sadhasivam via B4 Relay wrote:
> From: Manivannan Sadhasivam <manivannan.sadhasivam@....qualcomm.com>
> 
> To fix PCIe bridge resource allocation issues when powering PCIe
> switches with the pwrctrl driver, introduce APIs to explicitly power
> on and off all related devices simultaneously.
> ...

> +static void pci_pwrctrl_power_off_device(struct device_node *np)
> +{
> +	struct platform_device *pdev;
> +	int ret;
> +
> +	for_each_available_child_of_node_scoped(np, child)
> +		pci_pwrctrl_power_off_device(child);
> +
> +	pdev = of_find_device_by_node(np);
> +	if (pdev) {
> +		if (device_is_bound(&pdev->dev)) {
> +			ret = __pci_pwrctrl_power_off_device(&pdev->dev);
> +			if (ret)
> +				dev_err(&pdev->dev, "Failed to power off device: %d", ret);
> +		}
> +
> +		platform_device_put(pdev);
> +	}

Suggest this to reduce indentation:

  pdev = of_find_device_by_node(np);
  if (!pdev)
    return;

  if (device_is_bound(&pdev->dev)) {
    ...
  }

  platform_device_put(pdev);

> +static int pci_pwrctrl_power_on_device(struct device_node *np)
> +{
> +	struct platform_device *pdev;
> +	int ret;
> +
> +	for_each_available_child_of_node_scoped(np, child) {
> +		ret = pci_pwrctrl_power_on_device(child);
> +		if (ret)
> +			return ret;
> +	}
> +
> +	pdev = of_find_device_by_node(np);
> +	if (pdev) {
> +		if (!device_is_bound(&pdev->dev)) {
> +			/* FIXME: Use blocking wait instead of probe deferral */
> +			dev_dbg(&pdev->dev, "driver is not bound\n");
> +			ret = -EPROBE_DEFER;
> +		} else {
> +			ret = __pci_pwrctrl_power_on_device(&pdev->dev);
> +		}
> +		platform_device_put(pdev);
> +
> +		if (ret)
> +			return ret;
> +	}
> +
> +	return 0;

And this:

  pdev = of_find_device_by_node(np);
  if (!pdev)
    return 0;

  if (device_is_bound(&pdev->dev)) {
    ...
  } else {
    ...
  }

  platform_device_put(pdev);

  return ret;