On Monday, January 09, 2017 02:34:39 AM Lukas Wunner wrote: > On Fri, Jan 06, 2017 at 02:38:13AM +0100, Rafael J. Wysocki wrote: > > I sent patches [1-2/3] previosly a couple of weeks ago and there have not > > been any comments since then, so either they are fine by everybody or the > > timing was particularly bad and no one had the time to look at them. > > So far I was only able to peruse the "Device Power Management Data Types" > section (which is generated from include/linux/pm.h) and came across the > following: > > The description for the ->prepare hook says: > > If the transition is a suspend to memory or standby (that > is, not related to hibernation), the return value of @prepare() may be > used to indicate to the PM core to leave the device in runtime suspend > if applicable. > > Maybe I'm missing something
You are. Please see device_prepare(). > but in the places where the direct_complete > flag is calculated (e.g. in pci_dev_keep_suspended()) or where it's checked, > I don't see that we're differentiating anywhere whether we're going through > a suspend-to-RAM versus suspend-to-disk transition. So in the above snippet, > the portion "If the transition is a suspend to memory or standby (that is, > not related to hibernation)" seems wrong and should probably be removed. > > I know you're not touching this paragraph in the present commits, it's just > something that caught my eye while going over the rendered output. > > > Furthermore, the description for the ->freeze hook says: > > Analogous to @suspend(), but it should not enable the device to signal > wakeup events or change its power state. > > However looking at the PCI core it looks like this constraint isn't > satisfied, pci_dev_keep_suspended() (which gets called from ->prepare) > disables PME only if: > > if (pm_runtime_suspended(dev) && pci_dev->current_state < PCI_D3cold > && > !device_may_wakeup(dev)) > __pci_pme_active(pci_dev, false); > > Shouldn't this be something like: > > if (pm_runtime_suspended(dev) && pci_dev->current_state < PCI_D3cold > && > (!device_may_wakeup(dev) || (system_entering_hibernation() && > system_state != SYSTEM_POWER_OFF))) > __pci_pme_active(pci_dev, false); > > So that PME is disabled before entering the freeze phase for direct_complete > devices, but not before entering the poweroff phase. It should be safe to leave PME as is for the non-poweroff phases of hibernation, which is why the code is the way it is. Besides, this comment is about ->freeze, not about ->prepare. :-) Thanks, Rafael -- To unsubscribe from this list: send the line "unsubscribe linux-doc" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
