| Message ID | 4e8b490a18cc349318f0b71482d5dc7a7e9ca364.1474130360.git.lukas@wunner.de (mailing list archive) |
|---|---|
| State | Not Applicable, archived |
| Headers | show |
On Sunday, September 18, 2016 05:39:20 AM Lukas Wunner wrote: > Commit 58a1fbbb2ee8 ("PM / PCI / ACPI: Kick devices that might have been > reset by firmware") added a runtime resume for devices that were runtime > suspended when the system entered sleep. > > The motivation was that devices might be in a reset-power-on state after > waking from system sleep, so their power state as perceived by Linux > (stored in pci_dev->current_state) would no longer reflect reality. > By resuming such devices, we allow them to return to a low-power state > via autosuspend and also bring their current_state in sync with reality. > > However for devices that are *not* in a reset-power-on state, doing an > unconditional resume wastes energy. A more refined approach is called > for which issues a runtime resume only if the power state after > direct-complete is shallower than it was before. To achieve this, update > the device's current_state and compare it to its pre-sleep value. > > Cc: Rafael J. Wysocki <rjw@rjwysocki.net> > Signed-off-by: Lukas Wunner <lukas@wunner.de> Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> > --- > drivers/pci/pci-driver.c | 15 +++++++++++++-- > 1 file changed, 13 insertions(+), 2 deletions(-) > > diff --git a/drivers/pci/pci-driver.c b/drivers/pci/pci-driver.c > index e39a67c..fd4b9c4 100644 > --- a/drivers/pci/pci-driver.c > +++ b/drivers/pci/pci-driver.c > @@ -684,8 +684,19 @@ static int pci_pm_prepare(struct device *dev) > > static void pci_pm_complete(struct device *dev) > { > - pci_dev_complete_resume(to_pci_dev(dev)); > - pm_complete_with_resume_check(dev); > + struct pci_dev *pci_dev = to_pci_dev(dev); > + > + pci_dev_complete_resume(pci_dev); > + pm_generic_complete(dev); > + > + /* Resume device if platform firmware has put it in reset-power-on */ > + if (dev->power.direct_complete && pm_resume_via_firmware()) { > + pci_power_t pre_sleep_state = pci_dev->current_state; > + > + pci_update_current_state(pci_dev, pci_dev->current_state); > + if (pci_dev->current_state < pre_sleep_state) > + pm_request_resume(dev); > + } > } > > #else /* !CONFIG_PM_SLEEP */ >
diff --git a/drivers/pci/pci-driver.c b/drivers/pci/pci-driver.c index e39a67c..fd4b9c4 100644 --- a/drivers/pci/pci-driver.c +++ b/drivers/pci/pci-driver.c @@ -684,8 +684,19 @@ static int pci_pm_prepare(struct device *dev) static void pci_pm_complete(struct device *dev) { - pci_dev_complete_resume(to_pci_dev(dev)); - pm_complete_with_resume_check(dev); + struct pci_dev *pci_dev = to_pci_dev(dev); + + pci_dev_complete_resume(pci_dev); + pm_generic_complete(dev); + + /* Resume device if platform firmware has put it in reset-power-on */ + if (dev->power.direct_complete && pm_resume_via_firmware()) { + pci_power_t pre_sleep_state = pci_dev->current_state; + + pci_update_current_state(pci_dev, pci_dev->current_state); + if (pci_dev->current_state < pre_sleep_state) + pm_request_resume(dev); + } } #else /* !CONFIG_PM_SLEEP */
Commit 58a1fbbb2ee8 ("PM / PCI / ACPI: Kick devices that might have been reset by firmware") added a runtime resume for devices that were runtime suspended when the system entered sleep. The motivation was that devices might be in a reset-power-on state after waking from system sleep, so their power state as perceived by Linux (stored in pci_dev->current_state) would no longer reflect reality. By resuming such devices, we allow them to return to a low-power state via autosuspend and also bring their current_state in sync with reality. However for devices that are *not* in a reset-power-on state, doing an unconditional resume wastes energy. A more refined approach is called for which issues a runtime resume only if the power state after direct-complete is shallower than it was before. To achieve this, update the device's current_state and compare it to its pre-sleep value. Cc: Rafael J. Wysocki <rjw@rjwysocki.net> Signed-off-by: Lukas Wunner <lukas@wunner.de> --- drivers/pci/pci-driver.c | 15 +++++++++++++-- 1 file changed, 13 insertions(+), 2 deletions(-)