linux-kernel - Re: [PATCH v3 3/5] PCI/pwrctrl: Skip scanning for the device further if pwrctrl device is created

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Message-Id: <20250321025940.2103854-1-wei.fang@nxp.com>
Date: Fri, 21 Mar 2025 10:59:40 +0800
From: Wei Fang <wei.fang@....com>
To: devnull+manivannan.sadhasivam.linaro.org@...nel.org
Cc: bartosz.golaszewski@...aro.org,
	bhelgaas@...gle.com,
	brgl@...ev.pl,
	conor+dt@...nel.org,
	devicetree@...r.kernel.org,
	krzk+dt@...nel.org,
	linux-kernel@...r.kernel.org,
	linux-pci@...r.kernel.org,
	manivannan.sadhasivam@...aro.org,
	robh@...nel.org,
	netdev@...r.kernel.org
Subject: Re: [PATCH v3 3/5] PCI/pwrctrl: Skip scanning for the device further if pwrctrl device is created

@@ -2487,7 +2487,14 @@ static struct pci_dev *pci_scan_device(struct pci_bus *bus, int devfn)
 	struct pci_dev *dev;
 	u32 l;

-	pci_pwrctrl_create_device(bus, devfn);
+	/*
+	 * Create pwrctrl device (if required) for the PCI device to handle the
+	 * power state. If the pwrctrl device is created, then skip scanning
+	 * further as the pwrctrl core will rescan the bus after powering on
+	 * the device.
+	 */
+	if (pci_pwrctrl_create_device(bus, devfn))
+		return NULL;

Hi Manivannan,

The current patch logic is that if the pcie device node is found to have
the "xxx-supply" property, the scan will be skipped, and then the pwrctrl
driver will rescan and enable the regulators. However, after merging this
patch, there is a problem on our platform. The .probe() of our device
driver will not be called. The reason is that CONFIG_PCI_PWRCTL_SLOT is
not enabled at all in our configuration file, and the compatible string
of the device is also not added to the pwrctrl driver. I think other
platforms should also have similar problems, which undoubtedly make these
platforms be unstable. This patch has been applied, and I am not familiar
with this. Can you fix this problem? I mean that those platforms that do
not use pwrctrl can avoid skipping the scan.