| Message ID | 9d36522bc3d7e0ed1c1d5f653514d9fb0d34c0a8.1518941073.git.lukas@wunner.de (mailing list archive) |
|---|---|
| State | New, archived |
| Delegated to: | Bjorn Helgaas |
| Headers | show |
On Sun, Feb 18, 2018 at 09:38:32AM +0100, Lukas Wunner wrote: > There are PCI devices which are power-manageable by a nonstandard means, > such as a custom ACPI method. One example are discrete GPUs in hybrid > graphics laptops, another are Thunderbolt controllers in Macs. > > Such devices can't be put into D3cold with pci_set_power_state() because > pci_platform_power_transition() fails with -ENODEV. Instead they're put > into D3hot by pci_set_power_state() and subsequently into D3cold by > invoking the nonstandard means. However as a consequence the cached > current_state is incorrectly left at D3hot. > > What we need to do is walk the hierarchy below such a PCI device on > powerdown and update the current_state to D3cold. On powerup the PCI > device itself and the hierarchy below it is in D0uninitialized, so we > need to walk the hierarchy again and wake all devices, causing them to > be put into D0active and then letting them autosuspend as they see fit. > > To this end make pci_wakeup_bus() & pci_bus_set_current_state() public > so PCI drivers don't have to reinvent the wheel. > > Cc: Bjorn Helgaas <bhelgaas@google.com> > Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com> > Signed-off-by: Lukas Wunner <lukas@wunner.de> Acked-by: Bjorn Helgaas <bhelgaas@google.com> > --- > drivers/pci/pci.c | 8 ++++---- > include/linux/pci.h | 2 ++ > 2 files changed, 6 insertions(+), 4 deletions(-) > > diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c > index f694650235f2..6e6e322a5a7d 100644 > --- a/drivers/pci/pci.c > +++ b/drivers/pci/pci.c > @@ -800,7 +800,7 @@ static int pci_wakeup(struct pci_dev *pci_dev, void *ign) > * pci_wakeup_bus - Walk given bus and wake up devices on it > * @bus: Top bus of the subtree to walk. > */ > -static void pci_wakeup_bus(struct pci_bus *bus) > +void pci_wakeup_bus(struct pci_bus *bus) > { > if (bus) > pci_walk_bus(bus, pci_wakeup, NULL); > @@ -850,11 +850,11 @@ static int __pci_dev_set_current_state(struct pci_dev *dev, void *data) > } > > /** > - * __pci_bus_set_current_state - Walk given bus and set current state of devices > + * pci_bus_set_current_state - Walk given bus and set current state of devices > * @bus: Top bus of the subtree to walk. > * @state: state to be set > */ > -static void __pci_bus_set_current_state(struct pci_bus *bus, pci_power_t state) > +void pci_bus_set_current_state(struct pci_bus *bus, pci_power_t state) > { > if (bus) > pci_walk_bus(bus, __pci_dev_set_current_state, &state); > @@ -876,7 +876,7 @@ int __pci_complete_power_transition(struct pci_dev *dev, pci_power_t state) > ret = pci_platform_power_transition(dev, state); > /* Power off the bridge may power off the whole hierarchy */ > if (!ret && state == PCI_D3cold) > - __pci_bus_set_current_state(dev->subordinate, PCI_D3cold); > + pci_bus_set_current_state(dev->subordinate, PCI_D3cold); > return ret; > } > EXPORT_SYMBOL_GPL(__pci_complete_power_transition); > diff --git a/include/linux/pci.h b/include/linux/pci.h > index 024a1beda008..ae42289662df 100644 > --- a/include/linux/pci.h > +++ b/include/linux/pci.h > @@ -1147,6 +1147,8 @@ void pci_pme_wakeup_bus(struct pci_bus *bus); > void pci_d3cold_enable(struct pci_dev *dev); > void pci_d3cold_disable(struct pci_dev *dev); > bool pcie_relaxed_ordering_enabled(struct pci_dev *dev); > +void pci_wakeup_bus(struct pci_bus *bus); > +void pci_bus_set_current_state(struct pci_bus *bus, pci_power_t state); > > /* PCI Virtual Channel */ > int pci_save_vc_state(struct pci_dev *dev); > -- > 2.15.1 >
diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c index f694650235f2..6e6e322a5a7d 100644 --- a/drivers/pci/pci.c +++ b/drivers/pci/pci.c @@ -800,7 +800,7 @@ static int pci_wakeup(struct pci_dev *pci_dev, void *ign) * pci_wakeup_bus - Walk given bus and wake up devices on it * @bus: Top bus of the subtree to walk. */ -static void pci_wakeup_bus(struct pci_bus *bus) +void pci_wakeup_bus(struct pci_bus *bus) { if (bus) pci_walk_bus(bus, pci_wakeup, NULL); @@ -850,11 +850,11 @@ static int __pci_dev_set_current_state(struct pci_dev *dev, void *data) } /** - * __pci_bus_set_current_state - Walk given bus and set current state of devices + * pci_bus_set_current_state - Walk given bus and set current state of devices * @bus: Top bus of the subtree to walk. * @state: state to be set */ -static void __pci_bus_set_current_state(struct pci_bus *bus, pci_power_t state) +void pci_bus_set_current_state(struct pci_bus *bus, pci_power_t state) { if (bus) pci_walk_bus(bus, __pci_dev_set_current_state, &state); @@ -876,7 +876,7 @@ int __pci_complete_power_transition(struct pci_dev *dev, pci_power_t state) ret = pci_platform_power_transition(dev, state); /* Power off the bridge may power off the whole hierarchy */ if (!ret && state == PCI_D3cold) - __pci_bus_set_current_state(dev->subordinate, PCI_D3cold); + pci_bus_set_current_state(dev->subordinate, PCI_D3cold); return ret; } EXPORT_SYMBOL_GPL(__pci_complete_power_transition); diff --git a/include/linux/pci.h b/include/linux/pci.h index 024a1beda008..ae42289662df 100644 --- a/include/linux/pci.h +++ b/include/linux/pci.h @@ -1147,6 +1147,8 @@ void pci_pme_wakeup_bus(struct pci_bus *bus); void pci_d3cold_enable(struct pci_dev *dev); void pci_d3cold_disable(struct pci_dev *dev); bool pcie_relaxed_ordering_enabled(struct pci_dev *dev); +void pci_wakeup_bus(struct pci_bus *bus); +void pci_bus_set_current_state(struct pci_bus *bus, pci_power_t state); /* PCI Virtual Channel */ int pci_save_vc_state(struct pci_dev *dev);
There are PCI devices which are power-manageable by a nonstandard means, such as a custom ACPI method. One example are discrete GPUs in hybrid graphics laptops, another are Thunderbolt controllers in Macs. Such devices can't be put into D3cold with pci_set_power_state() because pci_platform_power_transition() fails with -ENODEV. Instead they're put into D3hot by pci_set_power_state() and subsequently into D3cold by invoking the nonstandard means. However as a consequence the cached current_state is incorrectly left at D3hot. What we need to do is walk the hierarchy below such a PCI device on powerdown and update the current_state to D3cold. On powerup the PCI device itself and the hierarchy below it is in D0uninitialized, so we need to walk the hierarchy again and wake all devices, causing them to be put into D0active and then letting them autosuspend as they see fit. To this end make pci_wakeup_bus() & pci_bus_set_current_state() public so PCI drivers don't have to reinvent the wheel. Cc: Bjorn Helgaas <bhelgaas@google.com> Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Signed-off-by: Lukas Wunner <lukas@wunner.de> --- drivers/pci/pci.c | 8 ++++---- include/linux/pci.h | 2 ++ 2 files changed, 6 insertions(+), 4 deletions(-)