On Thu, Oct 05, 2023 at 01:56:27PM -0500, Mario Limonciello wrote: > On 10/5/2023 13:53, Bjorn Helgaas wrote: > > On Wed, Oct 04, 2023 at 09:47:31AM -0500, Mario Limonciello wrote: > > > Before d3cold was stable userspace was allowed to influence the kernel's > > > decision of whether to enable d3cold for a device by a sysfs file > > > `d3cold_allowed`. This potentially allows userspace to break the suspend > > > for the system. > > > > Is "Before d3cold was stable" referring to a "d3cold" read-only > > variable, or to Linux functionality of using D3cold, or ...? > > I was referring to the previous thread's comments when I asked about the > history on it. > > > In what sense does the `d3cold_allowed` sysfs file break suspend? > > SoCs might not be able to get into their deepest sleep state if userspace > messes with it. > > > > For debugging purposes `pci_port_pm=` can be used to control whether > > > a PCI port will go into D3cold and runtime PM can be turned off by > > > sysfs on PCI end points. > > > > I guess this should be "pcie_port_pm=", which affects *all* PCIe > > ports? > > Yes. > > > Which sysfs file turns off runtime PM for endpoints? > > /sys/bus/pci/devices/*/power/control To close the loop on this, I think these are questions that should be answered in the commit log (actually, that's usually the case when I have questions, because future readers of the git history may have the same questions, and it's not practical to dig the answers out of the lore archive). Bjorn
