From 41044d5360685e78a869d40a168491a70cdb7e73 Mon Sep 17 00:00:00 2001 From: Alex Williamson Date: Tue, 23 Jan 2024 11:55:31 -0700 Subject: PCI: Fix active state requirement in PME polling The commit noted in fixes added a bogus requirement that runtime PM managed devices need to be in the RPM_ACTIVE state for PME polling. In fact, only devices in low power states should be polled. However there's still a requirement that the device config space must be accessible, which has implications for both the current state of the polled device and the parent bridge, when present. It's not sufficient to assume the bridge remains in D0 and cases have been observed where the bridge passes the D0 test, but the PM state indicates RPM_SUSPENDING and config space of the polled device becomes inaccessible during pci_pme_wakeup(). Therefore, since the bridge is already effectively required to be in the RPM_ACTIVE state, formalize this in the code and elevate the PM usage count to maintain the state while polling the subordinate device. This resolves a regression reported in the bugzilla below where a Thunderbolt/USB4 hierarchy fails to scan for an attached NVMe endpoint downstream of a bridge in a D3hot power state. Link: https://lore.kernel.org/r/20240123185548.1040096-1-alex.williamson@redhat.com Fixes: d3fcd7360338 ("PCI: Fix runtime PM race with PME polling") Reported-by: Sanath S Closes: https://bugzilla.kernel.org/show_bug.cgi?id=218360 Signed-off-by: Alex Williamson Signed-off-by: Bjorn Helgaas Tested-by: Sanath S Reviewed-by: Rafael J. Wysocki Cc: Lukas Wunner Cc: Mika Westerberg --- drivers/pci/pci.c | 37 ++++++++++++++++++++++--------------- 1 file changed, 22 insertions(+), 15 deletions(-) diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c index d8f11a078924c1..0a80156fe812fa 100644 --- a/drivers/pci/pci.c +++ b/drivers/pci/pci.c @@ -2496,29 +2496,36 @@ static void pci_pme_list_scan(struct work_struct *work) if (pdev->pme_poll) { struct pci_dev *bridge = pdev->bus->self; struct device *dev = &pdev->dev; - int pm_status; + struct device *bdev = bridge ? &bridge->dev : NULL; + int bref = 0; /* - * If bridge is in low power state, the - * configuration space of subordinate devices - * may be not accessible + * If we have a bridge, it should be in an active/D0 + * state or the configuration space of subordinate + * devices may not be accessible or stable over the + * course of the call. */ - if (bridge && bridge->current_state != PCI_D0) - continue; + if (bdev) { + bref = pm_runtime_get_if_active(bdev, true); + if (!bref) + continue; + + if (bridge->current_state != PCI_D0) + goto put_bridge; + } /* - * If the device is in a low power state it - * should not be polled either. + * The device itself should be suspended but config + * space must be accessible, therefore it cannot be in + * D3cold. */ - pm_status = pm_runtime_get_if_active(dev, true); - if (!pm_status) - continue; - - if (pdev->current_state != PCI_D3cold) + if (pm_runtime_suspended(dev) && + pdev->current_state != PCI_D3cold) pci_pme_wakeup(pdev, NULL); - if (pm_status > 0) - pm_runtime_put(dev); +put_bridge: + if (bref > 0) + pm_runtime_put(bdev); } else { list_del(&pme_dev->list); kfree(pme_dev); -- cgit 1.2.3-korg From 172c0cf519fb52860157c57067f1a58cfc0aa861 Mon Sep 17 00:00:00 2001 From: Siddharth Vadapalli Date: Fri, 16 Feb 2024 12:29:26 +0530 Subject: MAINTAINERS: Add Siddharth Vadapalli as PCI TI DRA7XX/J721E reviewer Since I have been contributing to the driver for a while and wish to help with the review process, add myself as a reviewer. Link: https://lore.kernel.org/r/20240216065926.473805-1-s-vadapalli@ti.com Signed-off-by: Siddharth Vadapalli Signed-off-by: Bjorn Helgaas --- MAINTAINERS | 1 + 1 file changed, 1 insertion(+) diff --git a/MAINTAINERS b/MAINTAINERS index 8d1052fa6a6924..a80c590d003597 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -16832,6 +16832,7 @@ F: drivers/pci/controller/dwc/*designware* PCI DRIVER FOR TI DRA7XX/J721E M: Vignesh Raghavendra +R: Siddharth Vadapalli L: linux-omap@vger.kernel.org L: linux-pci@vger.kernel.org L: linux-arm-kernel@lists.infradead.org (moderated for non-subscribers) -- cgit 1.2.3-korg