| Message ID | 5720276.eiOaOx1Qyb@kreacher (mailing list archive) |
|---|---|
| State | New, archived |
| Delegated to: | Bjorn Helgaas |
| Headers | show |
| Series | PCI: PM: Fix pci_power_up() | expand |
On Mon, Oct 14, 2019 at 7:25 PM Rafael J. Wysocki <rjw@rjwysocki.net> wrote: > Since there is no reason for that difference to exist, modify > pci_power_up() to follow pci_set_power_state() more closely and > invoke __pci_start_power_transition() from there to call the > platform firmware to power up the device (in case that's necessary). > > Fixes: db288c9c5f9d ("PCI / PM: restore the original behavior of pci_set_power_state()") > Reported-by: Daniel Drake <drake@endlessm.com> > Link: https://lore.kernel.org/linux-pm/CAD8Lp44TYxrMgPLkHCqF9hv6smEurMXvmmvmtyFhZ6Q4SE+dig@mail.gmail.com/T/#m21be74af263c6a34f36e0fc5c77c5449d9406925 > Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> > --- > > Daniel, please test this one. This one is working too, thanks Daniel
On Tue, Oct 15, 2019 at 7:11 AM Daniel Drake <drake@endlessm.com> wrote: > > On Mon, Oct 14, 2019 at 7:25 PM Rafael J. Wysocki <rjw@rjwysocki.net> wrote: > > Since there is no reason for that difference to exist, modify > > pci_power_up() to follow pci_set_power_state() more closely and > > invoke __pci_start_power_transition() from there to call the > > platform firmware to power up the device (in case that's necessary). > > > > Fixes: db288c9c5f9d ("PCI / PM: restore the original behavior of pci_set_power_state()") > > Reported-by: Daniel Drake <drake@endlessm.com> > > Link: https://lore.kernel.org/linux-pm/CAD8Lp44TYxrMgPLkHCqF9hv6smEurMXvmmvmtyFhZ6Q4SE+dig@mail.gmail.com/T/#m21be74af263c6a34f36e0fc5c77c5449d9406925 > > Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> > > --- > > > > Daniel, please test this one. > > This one is working too, thanks Thank you! Bjorn, any concerns?
On Mon, Oct 14, 2019 at 01:25:00PM +0200, Rafael J. Wysocki wrote: > From: Rafael J. Wysocki <rafael.j.wysocki@intel.com> > > There is an arbitrary difference between the system resume and > runtime resume code paths for PCI devices regarding the delay to > apply when switching the devices from D3cold to D0. > > Namely, pci_restore_standard_config() used in the runtime resume > code path calls pci_set_power_state() which in turn invokes > __pci_start_power_transition() to power up the device through the > platform firmware and that function applies the transition delay > (as per PCI Express Base Specification Revision 2.0, Section 6.6.1). > However, pci_pm_default_resume_early() used in the system resume > code path calls pci_power_up() which doesn't apply the delay at > all and that causes issues to occur during resume from > suspend-to-idle on some systems where the delay is required. > > Since there is no reason for that difference to exist, modify > pci_power_up() to follow pci_set_power_state() more closely and > invoke __pci_start_power_transition() from there to call the > platform firmware to power up the device (in case that's necessary). > > Fixes: db288c9c5f9d ("PCI / PM: restore the original behavior of pci_set_power_state()") > Reported-by: Daniel Drake <drake@endlessm.com> > Link: https://lore.kernel.org/linux-pm/CAD8Lp44TYxrMgPLkHCqF9hv6smEurMXvmmvmtyFhZ6Q4SE+dig@mail.gmail.com/T/#m21be74af263c6a34f36e0fc5c77c5449d9406925 > Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> > --- > > Daniel, please test this one. > > --- > drivers/pci/pci.c | 24 +++++++++++------------- > 1 file changed, 11 insertions(+), 13 deletions(-) > > Index: linux-pm/drivers/pci/pci.c > =================================================================== > --- linux-pm.orig/drivers/pci/pci.c > +++ linux-pm/drivers/pci/pci.c > @@ -959,19 +959,6 @@ void pci_refresh_power_state(struct pci_ > } > > /** > - * pci_power_up - Put the given device into D0 forcibly > - * @dev: PCI device to power up > - */ > -void pci_power_up(struct pci_dev *dev) > -{ > - if (platform_pci_power_manageable(dev)) > - platform_pci_set_power_state(dev, PCI_D0); > - > - pci_raw_set_power_state(dev, PCI_D0); > - pci_update_current_state(dev, PCI_D0); > -} > - > -/** > * pci_platform_power_transition - Use platform to change device power state > * @dev: PCI device to handle. > * @state: State to put the device into. > @@ -1154,6 +1141,17 @@ int pci_set_power_state(struct pci_dev * > EXPORT_SYMBOL(pci_set_power_state); > > /** > + * pci_power_up - Put the given device into D0 forcibly Not specifically for this patch, but what does "forcibly" mean? > + * @dev: PCI device to power up > + */ > +void pci_power_up(struct pci_dev *dev) > +{ > + __pci_start_power_transition(dev, PCI_D0); > + pci_raw_set_power_state(dev, PCI_D0); > + pci_update_current_state(dev, PCI_D0); There's not very much difference between: pci_power_up(dev); and pci_set_power_state(dev, PCI_D0); It looks like the main difference is that pci_set_power_state() calls __pci_complete_power_transition(), which ultimately calls acpi_pci_set_power_state() (for ACPI systems). So maybe "forcibly" means something like "ignoring any platform power management methods"? It's not obvious to me when we should skip the platform stuff or whether the skipping should be done at the high level (like calling either pci_power_up() or pci_set_power_state()) or at a lower level (e.g., if everybody called pci_set_power_state() and it could internally tell whether we're skipping the platform part). If we could unify the paths as much as possible, that would be nice, but if it's not feasible, it's not feasible. If you'd like me to push this for v5.4, let me know, otherwise you can apply my: Acked-by: Bjorn Helgaas <bhelgaas@google.com> > +} > + > +/** > * pci_choose_state - Choose the power state of a PCI device > * @dev: PCI device to be suspended > * @state: target sleep state for the whole system. This is the value > > >
On Tue, Oct 15, 2019 at 9:20 PM Bjorn Helgaas <helgaas@kernel.org> wrote: > > On Mon, Oct 14, 2019 at 01:25:00PM +0200, Rafael J. Wysocki wrote: > > From: Rafael J. Wysocki <rafael.j.wysocki@intel.com> > > > > There is an arbitrary difference between the system resume and > > runtime resume code paths for PCI devices regarding the delay to > > apply when switching the devices from D3cold to D0. > > > > Namely, pci_restore_standard_config() used in the runtime resume > > code path calls pci_set_power_state() which in turn invokes > > __pci_start_power_transition() to power up the device through the > > platform firmware and that function applies the transition delay > > (as per PCI Express Base Specification Revision 2.0, Section 6.6.1). > > However, pci_pm_default_resume_early() used in the system resume > > code path calls pci_power_up() which doesn't apply the delay at > > all and that causes issues to occur during resume from > > suspend-to-idle on some systems where the delay is required. > > > > Since there is no reason for that difference to exist, modify > > pci_power_up() to follow pci_set_power_state() more closely and > > invoke __pci_start_power_transition() from there to call the > > platform firmware to power up the device (in case that's necessary). > > > > Fixes: db288c9c5f9d ("PCI / PM: restore the original behavior of pci_set_power_state()") > > Reported-by: Daniel Drake <drake@endlessm.com> > > Link: https://lore.kernel.org/linux-pm/CAD8Lp44TYxrMgPLkHCqF9hv6smEurMXvmmvmtyFhZ6Q4SE+dig@mail.gmail.com/T/#m21be74af263c6a34f36e0fc5c77c5449d9406925 > > Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> > > --- > > > > Daniel, please test this one. > > > > --- > > drivers/pci/pci.c | 24 +++++++++++------------- > > 1 file changed, 11 insertions(+), 13 deletions(-) > > > > Index: linux-pm/drivers/pci/pci.c > > =================================================================== > > --- linux-pm.orig/drivers/pci/pci.c > > +++ linux-pm/drivers/pci/pci.c > > @@ -959,19 +959,6 @@ void pci_refresh_power_state(struct pci_ > > } > > > > /** > > - * pci_power_up - Put the given device into D0 forcibly > > - * @dev: PCI device to power up > > - */ > > -void pci_power_up(struct pci_dev *dev) > > -{ > > - if (platform_pci_power_manageable(dev)) > > - platform_pci_set_power_state(dev, PCI_D0); > > - > > - pci_raw_set_power_state(dev, PCI_D0); > > - pci_update_current_state(dev, PCI_D0); > > -} > > - > > -/** > > * pci_platform_power_transition - Use platform to change device power state > > * @dev: PCI device to handle. > > * @state: State to put the device into. > > @@ -1154,6 +1141,17 @@ int pci_set_power_state(struct pci_dev * > > EXPORT_SYMBOL(pci_set_power_state); > > > > /** > > + * pci_power_up - Put the given device into D0 forcibly > > Not specifically for this patch, but what does "forcibly" mean? > > > + * @dev: PCI device to power up > > + */ > > +void pci_power_up(struct pci_dev *dev) > > +{ > > + __pci_start_power_transition(dev, PCI_D0); > > + pci_raw_set_power_state(dev, PCI_D0); > > + pci_update_current_state(dev, PCI_D0); > > There's not very much difference between: > > pci_power_up(dev); > > and > > pci_set_power_state(dev, PCI_D0); > > It looks like the main difference is that pci_set_power_state() calls > __pci_complete_power_transition(), which ultimately calls > acpi_pci_set_power_state() (for ACPI systems). Yes, it does, for power states deeper than D0, which is not the case here. The main difference is the dev->current_state == state check in pci_set_power_state(), but in the resume case specifically dev->current_state == PCI_D0 doesn't matter, because the real power state of the device may be different. > So maybe "forcibly" means something like "ignoring any platform power > management methods"? It means "go into D0 no matter what the current cached value is". > It's not obvious to me when we should skip the > platform stuff or whether the skipping should be done at the high > level (like calling either pci_power_up() or pci_set_power_state()) or > at a lower level (e.g., if everybody called pci_set_power_state() and > it could internally tell whether we're skipping the platform part). For transitions into D0 __pci_start_power_transition() is the platform stuff, so we don't skip it and the other things that are present in pci_set_power_state() and are not there in pci_power_up() are simply unnecessary for transitions to D0. > If we could unify the paths as much as possible, that would be nice, > but if it's not feasible, it's not feasible. It kind of is, but I'd prefer to do it on top of this patch. First, the pci_update_current_state() in pci_power_up() can be moved to pci_pm_default_resume_early() which is the only caller of pci_power_up(). [The role of that pci_update_current_state() is to change the current_state value to D3cold if the device is not accessible (or the platform firmware says that it is D3cold, which may be the case after a failing attempt to use it to switch the device over to D0).] Next, if pci_power_up() is modified to return the return value of pci_raw_set_power_state(), pci_set_power_state() can be implemented (roughly) as sanitize the state argument if (dev->current_state == state) return 0; if (state == PCI_D0) return pci_power_up(); carry out a transition into a deeper power state. And so pci_power_up() will be used by pci_set_power_state(), for transitions into D0, and (directly) by pci_pm_default_resume_early(). How does that sound? > If you'd like me to push this for v5.4, let me know, otherwise you > can apply my: > > Acked-by: Bjorn Helgaas <bhelgaas@google.com> I will, thanks!
Index: linux-pm/drivers/pci/pci.c =================================================================== --- linux-pm.orig/drivers/pci/pci.c +++ linux-pm/drivers/pci/pci.c @@ -959,19 +959,6 @@ void pci_refresh_power_state(struct pci_ } /** - * pci_power_up - Put the given device into D0 forcibly - * @dev: PCI device to power up - */ -void pci_power_up(struct pci_dev *dev) -{ - if (platform_pci_power_manageable(dev)) - platform_pci_set_power_state(dev, PCI_D0); - - pci_raw_set_power_state(dev, PCI_D0); - pci_update_current_state(dev, PCI_D0); -} - -/** * pci_platform_power_transition - Use platform to change device power state * @dev: PCI device to handle. * @state: State to put the device into. @@ -1154,6 +1141,17 @@ int pci_set_power_state(struct pci_dev * EXPORT_SYMBOL(pci_set_power_state); /** + * pci_power_up - Put the given device into D0 forcibly + * @dev: PCI device to power up + */ +void pci_power_up(struct pci_dev *dev) +{ + __pci_start_power_transition(dev, PCI_D0); + pci_raw_set_power_state(dev, PCI_D0); + pci_update_current_state(dev, PCI_D0); +} + +/** * pci_choose_state - Choose the power state of a PCI device * @dev: PCI device to be suspended * @state: target sleep state for the whole system. This is the value