On Thu, Sep 14, 2023 at 04:53:32PM +0200, Lukas Wunner wrote: > On Thu, Sep 14, 2023 at 09:31:38AM -0500, Mario Limonciello wrote: > > On 9/14/2023 09:17, Lukas Wunner wrote: > > > On Wed, Sep 13, 2023 at 11:36:49AM -0500, Mario Limonciello wrote: > > > > On 9/13/2023 09:31, Lukas Wunner wrote: > > > > > If this only affects system sleep, not runtime PM, what you can do is > > > > > define a DECLARE_PCI_FIXUP_SUSPEND_LATE() which calls pci_d3cold_disable() > > > > > and also define a DECLARE_PCI_FIXUP_CLASS_RESUME_EARLY() which calls > > > > > pci_d3cold_enable(). > > > > > > > > > > And I think you can make those calls conditional on pm_suspend_no_platform() > > > > > to constrain to s2idle. > > > > > > > > > > User space should still be able to influence runtime PM via the > > > > > d3cold_allowed flag (unless I'm missing something). > > > > > > > > The part you're missing is that D3hot is affected by this issue too, > > > > otherwise it would be a good proposal. > > > > > > I recall that in an earlier version of the patch, you solved the issue > > > by amending pci_bridge_d3_possible(). > > > > > > Changing the dev->no_d3cold flag indirectly influences the bridge_d3 > > > flag (through pci_dev_check_d3cold() and pci_bridge_d3_update()). > > > > > > If dev->no_d3cold is set on a device below a port, that port is > > > prevented from entring D3hot because it would result in the > > > device effectively being in D3cold. > > > > > > So you might want to take a closer look at this approach despite > > > the flag suggesting that it only influences D3cold. > > > > Ah; I hadn't considered setting it on a device below the port. In this > > particular situation the only devices below the root port are USB > > controllers. > > > > If those devices don't go into D3 the system can't enter hardware sleep. > > If you set dev->no_d3cold on the USB controllers, they should still > be able to go to D3hot, but not D3cold, which perhaps might be sufficient. > It should prevent D3cold *and* D3hot on the Root Port above. And if you > set that on system sleep in a quirk and clear it on resume, runtime PM > shouldn't be affected. dev->no_d3cold appears to be mainly an administrative policy knob twidded via sysfs. There *are* a few cases where drivers (i915, nouveau, xhci) update it via pci_d3cold_enable() or pci_d3cold_disable(), but they all look vulnerable to issues if people use the sysfs knob, and I'm a little dubious that they're legit in the first place. This AMD Root Port issue is not an administrative choice; it's purely a functional problem of the device advertising that it supports PME# but not actually being able to do it. So if we can do this by fixing dev->pme_support (i.e., the copy of what it advertised), I'd rather do that. Bjorn
