| Message ID | 1472770801-30671-1-git-send-email-okaya@codeaurora.org |
|---|---|
| State | Changes Requested |
| Headers | show |
On Thu, Sep 01, 2016 at 07:00:00PM -0400, Sinan Kaya wrote: > A secondary bus reset causes settings to be lost by all downstream > devices on the tree. The code is currently saving and restoring device > states only when called from the VFIO path via pci_probe_reset_bus > and pci_reset_bus functions. > > Moving the save and restore into pci_reset_bridge_secondary_bus > so that all users of the API have the same behavior. > > Signed-off-by: Sinan Kaya <okaya@codeaurora.org> > --- > drivers/pci/pci.c | 36 +++++++++++++++--------------------- > 1 file changed, 15 insertions(+), 21 deletions(-) > > diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c > index aab9d51..b209378 100644 > --- a/drivers/pci/pci.c > +++ b/drivers/pci/pci.c > @@ -3860,19 +3860,6 @@ void __weak pcibios_reset_secondary_bus(struct pci_dev *dev) > pci_reset_secondary_bus(dev); > } > > -/** > - * pci_reset_bridge_secondary_bus - Reset the secondary bus on a PCI bridge. > - * @dev: Bridge device > - * > - * Use the bridge control register to assert reset on the secondary bus. > - * Devices on the secondary bus are left in power-on state. > - */ > -void pci_reset_bridge_secondary_bus(struct pci_dev *dev) > -{ > - pcibios_reset_secondary_bus(dev); > -} > -EXPORT_SYMBOL_GPL(pci_reset_bridge_secondary_bus); > - > static int pci_parent_bus_reset(struct pci_dev *dev, int probe) > { > struct pci_dev *pdev; > @@ -4362,6 +4349,21 @@ static void pci_slot_restore(struct pci_slot *slot) > } > } > > +/** > + * pci_reset_bridge_secondary_bus - Reset the secondary bus on a PCI bridge. > + * @dev: Bridge device > + * > + * Use the bridge control register to assert reset on the secondary bus. > + * Devices on the secondary bus are left in power-on state. This comment is no longer correct (you don't leave the devices in power-on state). > + */ > +void pci_reset_bridge_secondary_bus(struct pci_dev *dev) > +{ > + pci_bus_save_and_disable(dev->bus); "dev" is a bridge, and dev->bus is the bus on the *primary* side of the bridge, so I think this saves and disables the bridge itself. Don't you want dev->subordinate here instead? > + pcibios_reset_secondary_bus(dev); > + pci_bus_restore(dev->bus); > +} > +EXPORT_SYMBOL_GPL(pci_reset_bridge_secondary_bus); > + > static int pci_slot_reset(struct pci_slot *slot, int probe) > { > int rc; > @@ -4504,12 +4506,8 @@ int pci_reset_bus(struct pci_bus *bus) > if (rc) > return rc; > > - pci_bus_save_and_disable(bus); > - > rc = pci_bus_reset(bus, 0); > > - pci_bus_restore(bus); > - > return rc; > } > EXPORT_SYMBOL_GPL(pci_reset_bus); > @@ -4528,8 +4526,6 @@ int pci_try_reset_bus(struct pci_bus *bus) > if (rc) > return rc; > > - pci_bus_save_and_disable(bus); > - > if (pci_bus_trylock(bus)) { > might_sleep(); > pci_reset_bridge_secondary_bus(bus->self); > @@ -4537,8 +4533,6 @@ int pci_try_reset_bus(struct pci_bus *bus) > } else > rc = -EAGAIN; > > - pci_bus_restore(bus); > - > return rc; > } > EXPORT_SYMBOL_GPL(pci_try_reset_bus); > -- > 1.9.1 > -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Hi Bjorn, On 9/13/2016 12:42 PM, Bjorn Helgaas wrote: > > This comment is no longer correct (you don't leave the devices in > power-on state). Sorry about that, I can fix the comment. > >> + */ >> +void pci_reset_bridge_secondary_bus(struct pci_dev *dev) >> +{ >> + pci_bus_save_and_disable(dev->bus); > > "dev" is a bridge, and dev->bus is the bus on the *primary* side of > the bridge, so I think this saves and disables the bridge itself. > Don't you want dev->subordinate here instead? Yes, I need the subordinate. > >> + pcibios_reset_secondary_bus(dev); >> + pci_bus_restore(dev->bus); >> +} >> +EXPORT_SYMBOL_GPL(pci_reset_bridge_secondary_bus); >> +
On Thu, Sep 01, 2016 at 07:00:00PM -0400, Sinan Kaya wrote: > A secondary bus reset causes settings to be lost by all downstream > devices on the tree. The code is currently saving and restoring device > states only when called from the VFIO path via pci_probe_reset_bus > and pci_reset_bus functions. > > Moving the save and restore into pci_reset_bridge_secondary_bus > so that all users of the API have the same behavior. > > Signed-off-by: Sinan Kaya <okaya@codeaurora.org> > --- > drivers/pci/pci.c | 36 +++++++++++++++--------------------- > 1 file changed, 15 insertions(+), 21 deletions(-) > > diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c > index aab9d51..b209378 100644 > --- a/drivers/pci/pci.c > +++ b/drivers/pci/pci.c > @@ -3860,19 +3860,6 @@ void __weak pcibios_reset_secondary_bus(struct pci_dev *dev) > pci_reset_secondary_bus(dev); > } > > -/** > - * pci_reset_bridge_secondary_bus - Reset the secondary bus on a PCI bridge. > - * @dev: Bridge device > - * > - * Use the bridge control register to assert reset on the secondary bus. > - * Devices on the secondary bus are left in power-on state. > - */ > -void pci_reset_bridge_secondary_bus(struct pci_dev *dev) > -{ > - pcibios_reset_secondary_bus(dev); > -} > -EXPORT_SYMBOL_GPL(pci_reset_bridge_secondary_bus); > - > static int pci_parent_bus_reset(struct pci_dev *dev, int probe) > { > struct pci_dev *pdev; > @@ -4362,6 +4349,21 @@ static void pci_slot_restore(struct pci_slot *slot) > } > } > > +/** > + * pci_reset_bridge_secondary_bus - Reset the secondary bus on a PCI bridge. > + * @dev: Bridge device > + * > + * Use the bridge control register to assert reset on the secondary bus. > + * Devices on the secondary bus are left in power-on state. > + */ > +void pci_reset_bridge_secondary_bus(struct pci_dev *dev) > +{ > + pci_bus_save_and_disable(dev->bus); > + pcibios_reset_secondary_bus(dev); > + pci_bus_restore(dev->bus); This path eventually writes the Bridge Control register: pci_reset_bridge_secondary_bus pcibios_reset_secondary_bus pci_reset_secondary_bus pci_write_config_word(dev, PCI_BRIDGE_CONTROL, ctrl) But I think it'd be easy to call this on a non-bridge device, and I don't think there's anything in the path that checks whether this is actually a bridge. I wonder if we should check that somewhere, or maybe even change the interface so it takes a struct pci_bus instead of a pci_dev. > +} > +EXPORT_SYMBOL_GPL(pci_reset_bridge_secondary_bus); > + > static int pci_slot_reset(struct pci_slot *slot, int probe) > { > int rc; > @@ -4504,12 +4506,8 @@ int pci_reset_bus(struct pci_bus *bus) > if (rc) > return rc; > > - pci_bus_save_and_disable(bus); > - > rc = pci_bus_reset(bus, 0); > > - pci_bus_restore(bus); > - > return rc; > } > EXPORT_SYMBOL_GPL(pci_reset_bus); > @@ -4528,8 +4526,6 @@ int pci_try_reset_bus(struct pci_bus *bus) > if (rc) > return rc; > > - pci_bus_save_and_disable(bus); > - > if (pci_bus_trylock(bus)) { > might_sleep(); > pci_reset_bridge_secondary_bus(bus->self); > @@ -4537,8 +4533,6 @@ int pci_try_reset_bus(struct pci_bus *bus) > } else > rc = -EAGAIN; > > - pci_bus_restore(bus); > - > return rc; > } > EXPORT_SYMBOL_GPL(pci_try_reset_bus); > -- > 1.9.1 > -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On 9/13/2016 5:53 PM, Bjorn Helgaas wrote: >> + pci_bus_restore(dev->bus); > This path eventually writes the Bridge Control register: > > pci_reset_bridge_secondary_bus > pcibios_reset_secondary_bus > pci_reset_secondary_bus > pci_write_config_word(dev, PCI_BRIDGE_CONTROL, ctrl) > > But I think it'd be easy to call this on a non-bridge device, and I > don't think there's anything in the path that checks whether this is > actually a bridge. I wonder if we should check that somewhere, or > maybe even change the interface so it takes a struct pci_bus instead > of a pci_dev. > I'll change it to pci_bus. >> > +}
On 9/13/2016 7:20 PM, Sinan Kaya wrote: > On 9/13/2016 5:53 PM, Bjorn Helgaas wrote: >>> + pci_bus_restore(dev->bus); >> This path eventually writes the Bridge Control register: >> >> pci_reset_bridge_secondary_bus >> pcibios_reset_secondary_bus >> pci_reset_secondary_bus >> pci_write_config_word(dev, PCI_BRIDGE_CONTROL, ctrl) >> >> But I think it'd be easy to call this on a non-bridge device, and I >> don't think there's anything in the path that checks whether this is >> actually a bridge. I wonder if we should check that somewhere, or >> maybe even change the interface so it takes a struct pci_bus instead >> of a pci_dev. >> > > I'll change it to pci_bus. > >>>> +} > > Changing the API seems to become a bigger mess. pcibios_reset_secondary_bus has weaker friends in different architectures. I can move the check in pci_parent_bus_reset if (pci_is_root_bus(dev->bus) || dev->subordinate || !dev->bus->self || dev->dev_flags & PCI_DEV_FLAGS_NO_BUS_RESET) return -ENOTTY; inside pci_reset_bridge_secondary_bus instead.
diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c index aab9d51..b209378 100644 --- a/drivers/pci/pci.c +++ b/drivers/pci/pci.c @@ -3860,19 +3860,6 @@ void __weak pcibios_reset_secondary_bus(struct pci_dev *dev) pci_reset_secondary_bus(dev); } -/** - * pci_reset_bridge_secondary_bus - Reset the secondary bus on a PCI bridge. - * @dev: Bridge device - * - * Use the bridge control register to assert reset on the secondary bus. - * Devices on the secondary bus are left in power-on state. - */ -void pci_reset_bridge_secondary_bus(struct pci_dev *dev) -{ - pcibios_reset_secondary_bus(dev); -} -EXPORT_SYMBOL_GPL(pci_reset_bridge_secondary_bus); - static int pci_parent_bus_reset(struct pci_dev *dev, int probe) { struct pci_dev *pdev; @@ -4362,6 +4349,21 @@ static void pci_slot_restore(struct pci_slot *slot) } } +/** + * pci_reset_bridge_secondary_bus - Reset the secondary bus on a PCI bridge. + * @dev: Bridge device + * + * Use the bridge control register to assert reset on the secondary bus. + * Devices on the secondary bus are left in power-on state. + */ +void pci_reset_bridge_secondary_bus(struct pci_dev *dev) +{ + pci_bus_save_and_disable(dev->bus); + pcibios_reset_secondary_bus(dev); + pci_bus_restore(dev->bus); +} +EXPORT_SYMBOL_GPL(pci_reset_bridge_secondary_bus); + static int pci_slot_reset(struct pci_slot *slot, int probe) { int rc; @@ -4504,12 +4506,8 @@ int pci_reset_bus(struct pci_bus *bus) if (rc) return rc; - pci_bus_save_and_disable(bus); - rc = pci_bus_reset(bus, 0); - pci_bus_restore(bus); - return rc; } EXPORT_SYMBOL_GPL(pci_reset_bus); @@ -4528,8 +4526,6 @@ int pci_try_reset_bus(struct pci_bus *bus) if (rc) return rc; - pci_bus_save_and_disable(bus); - if (pci_bus_trylock(bus)) { might_sleep(); pci_reset_bridge_secondary_bus(bus->self); @@ -4537,8 +4533,6 @@ int pci_try_reset_bus(struct pci_bus *bus) } else rc = -EAGAIN; - pci_bus_restore(bus); - return rc; } EXPORT_SYMBOL_GPL(pci_try_reset_bus);
A secondary bus reset causes settings to be lost by all downstream devices on the tree. The code is currently saving and restoring device states only when called from the VFIO path via pci_probe_reset_bus and pci_reset_bus functions. Moving the save and restore into pci_reset_bridge_secondary_bus so that all users of the API have the same behavior. Signed-off-by: Sinan Kaya <okaya@codeaurora.org> --- drivers/pci/pci.c | 36 +++++++++++++++--------------------- 1 file changed, 15 insertions(+), 21 deletions(-)