From a0d2a959d3da343554523d26902de1d40a9e5c28 Mon Sep 17 00:00:00 2001 From: Lukas Wunner Date: Sun, 18 Sep 2016 05:39:20 +0200 Subject: [PATCH] PCI: Avoid unnecessary resume after direct-complete 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. Signed-off-by: Lukas Wunner Signed-off-by: Bjorn Helgaas Acked-by: Rafael J. Wysocki --- 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 e39a67c8ef39..fd4b9c48fd2a 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 */