We currently perform a mandatory runtime resume of all PCI devices on ->shutdown. However it is pointless to wake devices only to immediately power them down afterwards. (Or have the firmware reset them, in case of a reboot.) It seems there are only two cases when a runtime resume is actually necessary: If the driver has declared a ->shutdown callback or if kexec is in progress. Constrain resume of a device to these cases and let it slumber otherwise, thereby conserving energy and speeding up shutdown. Cc: Rafael J. Wysocki <rjw@xxxxxxxxxxxxx> Signed-off-by: Lukas Wunner <lukas@xxxxxxxxx> --- drivers/pci/pci-driver.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/drivers/pci/pci-driver.c b/drivers/pci/pci-driver.c index fd4b9c4..09a4e56 100644 --- a/drivers/pci/pci-driver.c +++ b/drivers/pci/pci-driver.c @@ -459,6 +459,11 @@ static void pci_device_shutdown(struct device *dev) struct pci_dev *pci_dev = to_pci_dev(dev); struct pci_driver *drv = pci_dev->driver; + /* Fast path for suspended devices */ + if (pm_runtime_suspended(dev) && (!drv || !drv->shutdown) && + !kexec_in_progress) + return; + pm_runtime_resume(dev); if (drv && drv->shutdown) -- 2.8.1 -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
