On Sun, Dec 01, 2024 at 01:51:08PM +0530, Manivannan Sadhasivam wrote: > The idea of pci_pwrctrl_unregister() is to remove the pwrctl device when the > associated PCI device gets removed. When this happens, the pwrctl driver will > turn off the power to the corresponding PCI device After pci_pwrctrl_unregister() is called from pci_stop_dev(), the device may be accessed by one of the calls in pci_destroy_dev(). E.g. pci_doe_destroy() may set the DOE Abort bit in the DOE Control Register if a DOE exchange is ongoing. One cannot assume that no such exchange is ongoing merely because the device was unbound from its driver. The PCI core may have legitimate reasons to perform a DOE exchange or generally access config space even after the device has been unbound. And IIUC, those accesses will fail if pwrctrl has powered the device down. Another example is pcie_aspm_exit_link_state(), which will adjust ASPM settings on device removal. So it seems to me that the call to pci_pwrctrl_unregister() needs to be moved to pci_doe_destroy(). However I'm worried that will break the symmetry with pci_pwrctrl_create_devices(), which is only called in the !pci_dev_is_added() case. Thanks, Lukas
