[+cc Bart, Krzysztof, update Mani's addr to kernel.org]
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).
I'm fine with this change, but I think the commit log leaves the wrong impression. If CONFIG_PCI_PWRCTRL is not enabled, we shouldn't do anything related to it, independent of what other platforms or drivers do.
So I wouldn't describe this as "the actual fix is converting all platforms to use pwrctrl." Even if all platforms use pwrctrl, we *still* shouldn't run pci_pwrctrl_create_device() unless CONFIG_PCI_PWRCTRL is enabled.
I think all we need to say is something like this:
We only need pci_pwrctrl_create_device() when CONFIG_PCI_PWRCTRL is enabled. Compile it out when CONFIG_PCI_PWRCTRL is not enabled.
Cc: stable@vger.kernel.org # 6.15 Fixes: 957f40d039a9 ("PCI/pwrctrl: Move creation of pwrctrl devices to pci_scan_device()")
Not sure about this. If the problem we're solving is "we run pwrctrl code when CONFIG_PCI_PWRCTRL is not enabled," 957f40d039a9 is not the commit that added that behavior.
Maybe 8fb18619d910 ("PCI/pwrctl: Create platform devices for child OF nodes of the port node") would be more appropriate?
Reported-by: Jim Quinlan james.quinlan@broadcom.com Closes: https://lore.kernel.org/r/CA+-6iNwgaByXEYD3j=-+H_PKAxXRU78svPMRHDKKci8AGXAUP...
I'm also not sure this really merits a "Closes:" tag. All this does is enable a workaround (disable CONFIG_PCI_PWRCTRL when brcmstb is enabled). That's not a fix because we *should* be able to enable both pwrctrl and brcmstb at the same time.
If 2489eeb777af ("PCI/pwrctrl: Skip scanning for the device further if pwrctrl device is created") was purely an optimization (see https://lore.kernel.org/r/20250701203526.GA1849466@bhelgaas), I think I would:
- Revert 2489eeb777af with a stable tag for v6.15, and
- Apply this patch with a Fixes: 8fb18619d910 ("PCI/pwrctl: Create platform devices for child OF nodes of the port node") but no stable tag. 8fb18619d910 appeared in v6.11 and the "don't enable CONFIG_PCI_PWRCTRL" workaround was enough for brcmstb until 2489eeb777af, so if we revert 2489eeb777af, we wouldn't need to backport *this* patch.
Signed-off-by: Manivannan Sadhasivam manivannan.sadhasivam@linaro.org
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 {