On Tue, Jul 01, 2025 at 12:17:31PM +0530, Manivannan Sadhasivam wrote:
If devicetree describes power supplies related to a PCI device, we previously created a pwrctrl device even if CONFIG_PCI_PWRCTL was not enabled.
When pci_pwrctrl_create_device() creates and returns a pwrctrl device, pci_scan_device() doesn't enumerate the PCI device. It assumes the pwrctrl core will rescan the bus after turning on the power. However, if CONFIG_PCI_PWRCTL is not enabled, the rescan never happens.
This may break PCI enumeration on any system that describes power supplies in devicetree but does not use pwrctrl. Jim reported that some brcmstb platforms break this way.
While the actual fix would be to convert all the platforms to use pwrctrl framework, we also need to skip creating the pwrctrl device if CONFIG_PCI_PWRCTL is not enabled and let the PCI core scan the device normally (assuming it is already powered on or by the controller driver).
Cc: stable@vger.kernel.org # 6.15 Fixes: 957f40d039a9 ("PCI/pwrctrl: Move creation of pwrctrl devices to pci_scan_device()") Reported-by: Jim Quinlan james.quinlan@broadcom.com Closes: https://lore.kernel.org/r/CA+-6iNwgaByXEYD3j=-+H_PKAxXRU78svPMRHDKKci8AGXAUP... Signed-off-by: Manivannan Sadhasivam manivannan.sadhasivam@linaro.org
I (finally) applied this to for-linus for v6.16 with the following commit log:
PCI/pwrctrl: Create pwrctrl devices only when CONFIG_PCI_PWRCTRL is enabled
If devicetree describes power supplies related to a PCI device, we unnecessarily created a pwrctrl device even if CONFIG_PCI_PWRCTL was not enabled.
We only need pci_pwrctrl_create_device() when CONFIG_PCI_PWRCTRL is enabled. Compile it out when CONFIG_PCI_PWRCTRL is not enabled.
When pci_pwrctrl_create_device() creates and returns a pwrctrl device, pci_scan_device() doesn't enumerate the PCI device. It assumes the pwrctrl core will rescan the bus after turning on the power. However, if CONFIG_PCI_PWRCTRL is not enabled, the rescan never happens, which breaks PCI enumeration on any system that describes power supplies in devicetree but does not use pwrctrl.
Jim reported that some brcmstb platforms break this way. The brcmstb driver is still broken if CONFIG_PCI_PWRCTRL is enabled, but this commit at least allows brcmstb to work when it's NOT enabled.
Fixes: 957f40d039a9 ("PCI/pwrctrl: Move creation of pwrctrl devices to pci_scan_device()") Reported-by: Jim Quinlan james.quinlan@broadcom.com Link: https://lore.kernel.org/r/CA+-6iNwgaByXEYD3j=-+H_PKAxXRU78svPMRHDKKci8AGXAUP... Signed-off-by: Manivannan Sadhasivam manivannan.sadhasivam@linaro.org [bhelgaas: commit log] Signed-off-by: Bjorn Helgaas bhelgaas@google.com Reviewed-by: Lukas Wunner lukas@wunner.de Cc: stable@vger.kernel.org # v6.15 Link: https://patch.msgid.link/20250701064731.52901-1-manivannan.sadhasivam@linaro...
Changes in v2:
- Used the stub instead of returning NULL inside the function
drivers/pci/probe.c | 7 +++++++ 1 file changed, 7 insertions(+)
diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c index 4b8693ec9e4c..e6a34db77826 100644 --- a/drivers/pci/probe.c +++ b/drivers/pci/probe.c @@ -2508,6 +2508,7 @@ bool pci_bus_read_dev_vendor_id(struct pci_bus *bus, int devfn, u32 *l, } EXPORT_SYMBOL(pci_bus_read_dev_vendor_id); +#if IS_ENABLED(CONFIG_PCI_PWRCTRL) static struct platform_device *pci_pwrctrl_create_device(struct pci_bus *bus, int devfn) { struct pci_host_bridge *host = pci_find_host_bridge(bus); @@ -2537,6 +2538,12 @@ static struct platform_device *pci_pwrctrl_create_device(struct pci_bus *bus, in return pdev; } +#else +static struct platform_device *pci_pwrctrl_create_device(struct pci_bus *bus, int devfn) +{
- return NULL;
+} +#endif /*
- Read the config data for a PCI device, sanity-check it,
-- 2.43.0