From c01163dbd1b8aa016c163ff4bf3a2e90311504f1 Mon Sep 17 00:00:00 2001 From: Bjorn Helgaas Date: Fri, 9 Sep 2022 15:25:05 -0500 Subject: [PATCH] PCI/PM: Always disable PTM for all devices during suspend We want to disable PTM on Root Ports because that allows some chips, e.g., Intel mobile chips since Coffee Lake, to enter a lower-power PM state. That means we also have to disable PTM on downstream devices. PCIe r6.0, sec 2.2.8, recommends that functions support generation of messages in non-D0 states, so we have to assume Switch Upstream Ports or Endpoints may send PTM Requests while in D1, D2, and D3hot. A PTM message received by a Downstream Port (including a Root Port) with PTM disabled must be treated as an Unsupported Request (sec 6.21.3). PTM was previously disabled only for Root Ports, and it was disabled in pci_prepare_to_sleep(), which is not called at all if a driver supports legacy PM or does its own state saving. Instead, disable PTM early in pci_pm_suspend() and pci_pm_runtime_suspend() so we do it in all cases. Previously PTM was disabled *after* saving device state, so the state restore on resume automatically re-enabled it. Since we now disable PTM *before* saving state, we must explicitly re-enable it in pci_pm_resume() and pci_pm_runtime_resume(). Here's a sample of errors that occur when PTM is disabled only on the Root Port. With this topology: 0000:00:1d.0 Root Port to [bus 08-71] 0000:08:00.0 Switch Upstream Port to [bus 09-71] Kai-Heng reported errors like this: pcieport 0000:00:1d.0: [20] UnsupReq (First) pcieport 0000:00:1d.0: AER: TLP Header: 34000000 08000052 00000000 00000000 Decoding TLP header 0x34...... (0011 0100b) and 0x08000052: Fmt 001b 4 DW header, no data Type 1 0100b Msg (Local - Terminate at Receiver) Requester ID 0x0800 Bus 08 Devfn 00.0 Message Code 0x52 0101 0010b PTM Request The 00:1d.0 Root Port logged an Unsupported Request error when it received a PTM Request with Requester ID 08:00.0. Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=215453 Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=216210 Fixes: a697f072f5da ("PCI: Disable PTM during suspend to save power") Link: https://lore.kernel.org/r/20220909202505.314195-10-helgaas@kernel.org Reported-by: Kai-Heng Feng Tested-by: Rajvi Jingar Signed-off-by: Bjorn Helgaas Reviewed-by: Mika Westerberg --- drivers/pci/pci-driver.c | 11 +++++++++++ drivers/pci/pci.c | 28 ++-------------------------- 2 files changed, 13 insertions(+), 26 deletions(-) diff --git a/drivers/pci/pci-driver.c b/drivers/pci/pci-driver.c index 49238dd..5d8c37c 100644 --- a/drivers/pci/pci-driver.c +++ b/drivers/pci/pci-driver.c @@ -774,6 +774,12 @@ static int pci_pm_suspend(struct device *dev) pci_dev->skip_bus_pm = false; + /* + * Disabling PTM allows some systems, e.g., Intel mobile chips + * since Coffee Lake, to enter a lower-power PM state. + */ + pci_suspend_ptm(pci_dev); + if (pci_has_legacy_pm_support(pci_dev)) return pci_legacy_suspend(dev, PMSG_SUSPEND); @@ -987,6 +993,8 @@ static int pci_pm_resume(struct device *dev) if (pci_dev->state_saved) pci_restore_standard_config(pci_dev); + pci_resume_ptm(pci_dev); + if (pci_has_legacy_pm_support(pci_dev)) return pci_legacy_resume(dev); @@ -1274,6 +1282,8 @@ static int pci_pm_runtime_suspend(struct device *dev) pci_power_t prev = pci_dev->current_state; int error; + pci_suspend_ptm(pci_dev); + /* * If pci_dev->driver is not set (unbound), we leave the device in D0, * but it may go to D3cold when the bridge above it runtime suspends. @@ -1335,6 +1345,7 @@ static int pci_pm_runtime_resume(struct device *dev) * D3cold when the bridge above it runtime suspended. */ pci_pm_default_resume_early(pci_dev); + pci_resume_ptm(pci_dev); if (!pci_dev->driver) return 0; diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c index 83818f8..107afa0 100644 --- a/drivers/pci/pci.c +++ b/drivers/pci/pci.c @@ -2706,24 +2706,12 @@ int pci_prepare_to_sleep(struct pci_dev *dev) if (target_state == PCI_POWER_ERROR) return -EIO; - /* - * There are systems (for example, Intel mobile chips since Coffee - * Lake) where the power drawn while suspended can be significantly - * reduced by disabling PTM on PCIe root ports as this allows the - * port to enter a lower-power PM state and the SoC to reach a - * lower-power idle state as a whole. - */ - if (pci_pcie_type(dev) == PCI_EXP_TYPE_ROOT_PORT) - pci_suspend_ptm(dev); - pci_enable_wake(dev, target_state, wakeup); error = pci_set_power_state(dev, target_state); - if (error) { + if (error) pci_enable_wake(dev, target_state, false); - pci_restore_ptm_state(dev); - } return error; } @@ -2764,24 +2752,12 @@ int pci_finish_runtime_suspend(struct pci_dev *dev) if (target_state == PCI_POWER_ERROR) return -EIO; - /* - * There are systems (for example, Intel mobile chips since Coffee - * Lake) where the power drawn while suspended can be significantly - * reduced by disabling PTM on PCIe root ports as this allows the - * port to enter a lower-power PM state and the SoC to reach a - * lower-power idle state as a whole. - */ - if (pci_pcie_type(dev) == PCI_EXP_TYPE_ROOT_PORT) - pci_suspend_ptm(dev); - __pci_enable_wake(dev, target_state, pci_dev_run_wake(dev)); error = pci_set_power_state(dev, target_state); - if (error) { + if (error) pci_enable_wake(dev, target_state, false); - pci_restore_ptm_state(dev); - } return error; } -- 2.7.4