PCI/ASPM: Fix deadlock when enabling ASPM
commit1e56086415upstream. A last minute revert in 6.7-final introduced a potential deadlock when enabling ASPM during probe of Qualcomm PCIe controllers as reported by lockdep: ============================================ WARNING: possible recursive locking detected 6.7.0 #40 Not tainted -------------------------------------------- kworker/u16:5/90 is trying to acquire lock: ffffacfa78ced000 (pci_bus_sem){++++}-{3:3}, at: pcie_aspm_pm_state_change+0x58/0xdc but task is already holding lock: ffffacfa78ced000 (pci_bus_sem){++++}-{3:3}, at: pci_walk_bus+0x34/0xbc other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock(pci_bus_sem); lock(pci_bus_sem); *** DEADLOCK *** Call trace: print_deadlock_bug+0x25c/0x348 __lock_acquire+0x10a4/0x2064 lock_acquire+0x1e8/0x318 down_read+0x60/0x184 pcie_aspm_pm_state_change+0x58/0xdc pci_set_full_power_state+0xa8/0x114 pci_set_power_state+0xc4/0x120 qcom_pcie_enable_aspm+0x1c/0x3c [pcie_qcom] pci_walk_bus+0x64/0xbc qcom_pcie_host_post_init_2_7_0+0x28/0x34 [pcie_qcom] The deadlock can easily be reproduced on machines like the Lenovo ThinkPad X13s by adding a delay to increase the race window during asynchronous probe where another thread can take a write lock. Add a new pci_set_power_state_locked() and associated helper functions that can be called with the PCI bus semaphore held to avoid taking the read lock twice. Link: https://lore.kernel.org/r/ZZu0qx2cmn7IwTyQ@hovoldconsulting.com Link: https://lore.kernel.org/r/20240130100243.11011-1-johan+linaro@kernel.org Fixes:f93e71aea6("Revert "PCI/ASPM: Remove pcie_aspm_pm_state_change()"") Signed-off-by: Johan Hovold <johan+linaro@kernel.org> Signed-off-by: Bjorn Helgaas <bhelgaas@google.com> Cc: <stable@vger.kernel.org> # 6.7 [bhelgaas: backported to v6.1.y, which containsb9c370b61d("Revert "PCI/ASPM: Remove pcie_aspm_pm_state_change()""), a backport off93e71aea6. This omits the drivers/pci/controller/dwc/pcie-qcom.c hunk that updates qcom_pcie_enable_aspm(), which was added by9f4f3dfad8("PCI: qcom: Enable ASPM for platforms supporting 1.9.0 ops"), which is not present in v6.1.87.] Signed-off-by: Bjorn Helgaas <bhelgaas@google.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Johan Hovold
Greg Kroah-Hartman
parent
67a877128b
commit
0f7908a016
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@ -379,21 +379,8 @@ void pci_bus_add_devices(const struct pci_bus *bus)
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}
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EXPORT_SYMBOL(pci_bus_add_devices);
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/** pci_walk_bus - walk devices on/under bus, calling callback.
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* @top bus whose devices should be walked
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* @cb callback to be called for each device found
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* @userdata arbitrary pointer to be passed to callback.
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*
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* Walk the given bus, including any bridged devices
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* on buses under this bus. Call the provided callback
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* on each device found.
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*
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* We check the return of @cb each time. If it returns anything
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* other than 0, we break out.
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*
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*/
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void pci_walk_bus(struct pci_bus *top, int (*cb)(struct pci_dev *, void *),
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void *userdata)
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static void __pci_walk_bus(struct pci_bus *top, int (*cb)(struct pci_dev *, void *),
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void *userdata, bool locked)
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{
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struct pci_dev *dev;
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struct pci_bus *bus;
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@ -401,7 +388,8 @@ void pci_walk_bus(struct pci_bus *top, int (*cb)(struct pci_dev *, void *),
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int retval;
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bus = top;
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down_read(&pci_bus_sem);
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if (!locked)
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down_read(&pci_bus_sem);
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next = top->devices.next;
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for (;;) {
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if (next == &bus->devices) {
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@ -424,10 +412,37 @@ void pci_walk_bus(struct pci_bus *top, int (*cb)(struct pci_dev *, void *),
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if (retval)
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break;
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}
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up_read(&pci_bus_sem);
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if (!locked)
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up_read(&pci_bus_sem);
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}
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/**
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* pci_walk_bus - walk devices on/under bus, calling callback.
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* @top: bus whose devices should be walked
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* @cb: callback to be called for each device found
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* @userdata: arbitrary pointer to be passed to callback
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*
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* Walk the given bus, including any bridged devices
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* on buses under this bus. Call the provided callback
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* on each device found.
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*
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* We check the return of @cb each time. If it returns anything
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* other than 0, we break out.
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*/
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void pci_walk_bus(struct pci_bus *top, int (*cb)(struct pci_dev *, void *), void *userdata)
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{
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__pci_walk_bus(top, cb, userdata, false);
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}
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EXPORT_SYMBOL_GPL(pci_walk_bus);
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void pci_walk_bus_locked(struct pci_bus *top, int (*cb)(struct pci_dev *, void *), void *userdata)
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{
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lockdep_assert_held(&pci_bus_sem);
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__pci_walk_bus(top, cb, userdata, true);
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}
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EXPORT_SYMBOL_GPL(pci_walk_bus_locked);
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struct pci_bus *pci_bus_get(struct pci_bus *bus)
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{
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if (bus)
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@ -1258,6 +1258,7 @@ end:
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/**
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* pci_set_full_power_state - Put a PCI device into D0 and update its state
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* @dev: PCI device to power up
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* @locked: whether pci_bus_sem is held
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*
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* Call pci_power_up() to put @dev into D0, read from its PCI_PM_CTRL register
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* to confirm the state change, restore its BARs if they might be lost and
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@ -1267,7 +1268,7 @@ end:
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* to D0, it is more efficient to use pci_power_up() directly instead of this
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* function.
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*/
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static int pci_set_full_power_state(struct pci_dev *dev)
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static int pci_set_full_power_state(struct pci_dev *dev, bool locked)
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{
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u16 pmcsr;
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int ret;
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@ -1303,7 +1304,7 @@ static int pci_set_full_power_state(struct pci_dev *dev)
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}
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if (dev->bus->self)
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pcie_aspm_pm_state_change(dev->bus->self);
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pcie_aspm_pm_state_change(dev->bus->self, locked);
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return 0;
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}
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@ -1332,10 +1333,22 @@ void pci_bus_set_current_state(struct pci_bus *bus, pci_power_t state)
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pci_walk_bus(bus, __pci_dev_set_current_state, &state);
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}
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static void __pci_bus_set_current_state(struct pci_bus *bus, pci_power_t state, bool locked)
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{
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if (!bus)
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return;
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if (locked)
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pci_walk_bus_locked(bus, __pci_dev_set_current_state, &state);
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else
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pci_walk_bus(bus, __pci_dev_set_current_state, &state);
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}
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/**
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* pci_set_low_power_state - Put a PCI device into a low-power state.
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* @dev: PCI device to handle.
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* @state: PCI power state (D1, D2, D3hot) to put the device into.
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* @locked: whether pci_bus_sem is held
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*
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* Use the device's PCI_PM_CTRL register to put it into a low-power state.
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*
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@ -1346,7 +1359,7 @@ void pci_bus_set_current_state(struct pci_bus *bus, pci_power_t state)
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* 0 if device already is in the requested state.
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* 0 if device's power state has been successfully changed.
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*/
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static int pci_set_low_power_state(struct pci_dev *dev, pci_power_t state)
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static int pci_set_low_power_state(struct pci_dev *dev, pci_power_t state, bool locked)
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{
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u16 pmcsr;
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@ -1400,29 +1413,12 @@ static int pci_set_low_power_state(struct pci_dev *dev, pci_power_t state)
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pci_power_name(state));
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if (dev->bus->self)
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pcie_aspm_pm_state_change(dev->bus->self);
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pcie_aspm_pm_state_change(dev->bus->self, locked);
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return 0;
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}
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/**
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* pci_set_power_state - Set the power state of a PCI device
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* @dev: PCI device to handle.
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* @state: PCI power state (D0, D1, D2, D3hot) to put the device into.
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*
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* Transition a device to a new power state, using the platform firmware and/or
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* the device's PCI PM registers.
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*
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* RETURN VALUE:
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* -EINVAL if the requested state is invalid.
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* -EIO if device does not support PCI PM or its PM capabilities register has a
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* wrong version, or device doesn't support the requested state.
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* 0 if the transition is to D1 or D2 but D1 and D2 are not supported.
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* 0 if device already is in the requested state.
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* 0 if the transition is to D3 but D3 is not supported.
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* 0 if device's power state has been successfully changed.
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*/
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int pci_set_power_state(struct pci_dev *dev, pci_power_t state)
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static int __pci_set_power_state(struct pci_dev *dev, pci_power_t state, bool locked)
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{
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int error;
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@ -1446,7 +1442,7 @@ int pci_set_power_state(struct pci_dev *dev, pci_power_t state)
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return 0;
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if (state == PCI_D0)
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return pci_set_full_power_state(dev);
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return pci_set_full_power_state(dev, locked);
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/*
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* This device is quirked not to be put into D3, so don't put it in
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@ -1460,16 +1456,16 @@ int pci_set_power_state(struct pci_dev *dev, pci_power_t state)
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* To put the device in D3cold, put it into D3hot in the native
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* way, then put it into D3cold using platform ops.
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*/
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error = pci_set_low_power_state(dev, PCI_D3hot);
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error = pci_set_low_power_state(dev, PCI_D3hot, locked);
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if (pci_platform_power_transition(dev, PCI_D3cold))
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return error;
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/* Powering off a bridge may power off the whole hierarchy */
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if (dev->current_state == PCI_D3cold)
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pci_bus_set_current_state(dev->subordinate, PCI_D3cold);
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__pci_bus_set_current_state(dev->subordinate, PCI_D3cold, locked);
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} else {
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error = pci_set_low_power_state(dev, state);
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error = pci_set_low_power_state(dev, state, locked);
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if (pci_platform_power_transition(dev, state))
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return error;
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@ -1477,8 +1473,38 @@ int pci_set_power_state(struct pci_dev *dev, pci_power_t state)
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return 0;
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}
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/**
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* pci_set_power_state - Set the power state of a PCI device
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* @dev: PCI device to handle.
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* @state: PCI power state (D0, D1, D2, D3hot) to put the device into.
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*
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* Transition a device to a new power state, using the platform firmware and/or
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* the device's PCI PM registers.
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*
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* RETURN VALUE:
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* -EINVAL if the requested state is invalid.
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* -EIO if device does not support PCI PM or its PM capabilities register has a
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* wrong version, or device doesn't support the requested state.
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* 0 if the transition is to D1 or D2 but D1 and D2 are not supported.
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* 0 if device already is in the requested state.
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* 0 if the transition is to D3 but D3 is not supported.
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* 0 if device's power state has been successfully changed.
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*/
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int pci_set_power_state(struct pci_dev *dev, pci_power_t state)
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{
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return __pci_set_power_state(dev, state, false);
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}
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EXPORT_SYMBOL(pci_set_power_state);
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int pci_set_power_state_locked(struct pci_dev *dev, pci_power_t state)
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{
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lockdep_assert_held(&pci_bus_sem);
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return __pci_set_power_state(dev, state, true);
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}
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EXPORT_SYMBOL(pci_set_power_state_locked);
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#define PCI_EXP_SAVE_REGS 7
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static struct pci_cap_saved_state *_pci_find_saved_cap(struct pci_dev *pci_dev,
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@ -556,12 +556,12 @@ bool pcie_wait_for_link(struct pci_dev *pdev, bool active);
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#ifdef CONFIG_PCIEASPM
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void pcie_aspm_init_link_state(struct pci_dev *pdev);
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void pcie_aspm_exit_link_state(struct pci_dev *pdev);
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void pcie_aspm_pm_state_change(struct pci_dev *pdev);
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void pcie_aspm_pm_state_change(struct pci_dev *pdev, bool locked);
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void pcie_aspm_powersave_config_link(struct pci_dev *pdev);
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#else
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static inline void pcie_aspm_init_link_state(struct pci_dev *pdev) { }
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static inline void pcie_aspm_exit_link_state(struct pci_dev *pdev) { }
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static inline void pcie_aspm_pm_state_change(struct pci_dev *pdev) { }
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static inline void pcie_aspm_pm_state_change(struct pci_dev *pdev, bool locked) { }
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static inline void pcie_aspm_powersave_config_link(struct pci_dev *pdev) { }
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#endif
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@ -1055,8 +1055,11 @@ void pcie_aspm_exit_link_state(struct pci_dev *pdev)
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up_read(&pci_bus_sem);
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}
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/* @pdev: the root port or switch downstream port */
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void pcie_aspm_pm_state_change(struct pci_dev *pdev)
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/*
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* @pdev: the root port or switch downstream port
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* @locked: whether pci_bus_sem is held
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*/
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void pcie_aspm_pm_state_change(struct pci_dev *pdev, bool locked)
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{
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struct pcie_link_state *link = pdev->link_state;
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@ -1066,12 +1069,14 @@ void pcie_aspm_pm_state_change(struct pci_dev *pdev)
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* Devices changed PM state, we should recheck if latency
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* meets all functions' requirement
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*/
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down_read(&pci_bus_sem);
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if (!locked)
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down_read(&pci_bus_sem);
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mutex_lock(&aspm_lock);
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pcie_update_aspm_capable(link->root);
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pcie_config_aspm_path(link);
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mutex_unlock(&aspm_lock);
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up_read(&pci_bus_sem);
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if (!locked)
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up_read(&pci_bus_sem);
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}
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void pcie_aspm_powersave_config_link(struct pci_dev *pdev)
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@ -1383,6 +1383,7 @@ int pci_load_and_free_saved_state(struct pci_dev *dev,
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struct pci_saved_state **state);
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int pci_platform_power_transition(struct pci_dev *dev, pci_power_t state);
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int pci_set_power_state(struct pci_dev *dev, pci_power_t state);
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int pci_set_power_state_locked(struct pci_dev *dev, pci_power_t state);
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pci_power_t pci_choose_state(struct pci_dev *dev, pm_message_t state);
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bool pci_pme_capable(struct pci_dev *dev, pci_power_t state);
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void pci_pme_active(struct pci_dev *dev, bool enable);
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@ -1553,6 +1554,8 @@ int pci_scan_bridge(struct pci_bus *bus, struct pci_dev *dev, int max,
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void pci_walk_bus(struct pci_bus *top, int (*cb)(struct pci_dev *, void *),
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void *userdata);
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void pci_walk_bus_locked(struct pci_bus *top, int (*cb)(struct pci_dev *, void *),
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void *userdata);
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int pci_cfg_space_size(struct pci_dev *dev);
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unsigned char pci_bus_max_busnr(struct pci_bus *bus);
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void pci_setup_bridge(struct pci_bus *bus);
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@ -1884,6 +1887,8 @@ static inline int pci_save_state(struct pci_dev *dev) { return 0; }
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static inline void pci_restore_state(struct pci_dev *dev) { }
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static inline int pci_set_power_state(struct pci_dev *dev, pci_power_t state)
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{ return 0; }
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static inline int pci_set_power_state_locked(struct pci_dev *dev, pci_power_t state)
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{ return 0; }
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static inline int pci_wake_from_d3(struct pci_dev *dev, bool enable)
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{ return 0; }
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static inline pci_power_t pci_choose_state(struct pci_dev *dev,
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