On Thu, Jan 18, 2024 at 11:50:49AM -0700, Alex Williamson wrote: > On Thu, 3 Aug 2023 11:12:33 -0600 Alex Williamson <alex.williamson@xxxxxxxxxx wrote: > > Testing that a device is not currently in a low power state provides no > > guarantees that the device is not immenently transitioning to such a state. > > We need to increment the PM usage counter before accessing the device. > > Since we don't wish to wake the device for PME polling, do so only if the > > device is already active by using pm_runtime_get_if_active(). > > > > Signed-off-by: Alex Williamson <alex.williamson@xxxxxxxxxx> > > --- > > drivers/pci/pci.c | 23 ++++++++++++++++------- > > 1 file changed, 16 insertions(+), 7 deletions(-) > > Resurrecting this patch (currently commit d3fcd7360338) for discussion > as it's been identified as the source of a regression in: > > https://bugzilla.kernel.org/show_bug.cgi?id=218360 > > Copying Mika, Lukas, and Rafael as it's related to: > > 000dd5316e1c ("PCI: Do not poll for PME if the device is in D3cold") > > where we skip devices in D3cold when processing the PME list. > > I think the issue in the above bz is that the downstream TB3/USB4 port > is in D3 (presumably D3hot) and I therefore infer the device is in state > RPM_SUSPENDED. This commit is attempting to make sure the device power > state is stable across the call such that it does not transition into > D3cold while we're accessing it. > > To do that I used pm_runtime_get_if_active(), but in retrospect this > requires the device to be in RPM_ACTIVE so we end up skipping anything > suspended or transitioning. How about dropping the calls to pm_runtime_get_if_active() and pm_runtime_put() and instead simply do: if (pm_runtime_suspended(&pdev->dev) && pdev->current_state != PCI_D3cold) pci_pme_wakeup(pdev, NULL); Thanks, Lukas
