On Wed, Mar 25, 2020 at 9:49 PM Alan Stern <stern@xxxxxxxxxxxxxxxxxxx> wrote: > > On Wed, 25 Mar 2020, Qais Yousef wrote: > > > Thanks for all the hints Alan. > > > > I think I figured it out, the below patch seems to fix it for me. Looking > > at other drivers resume functions it seems we're missing the > > pm_runtime_disable()->set_active()->enable() dance. Doing that fixes the > > warning and the dev_err() in driver/base/power. > > Ah, yes. This should have been added years ago; guess I forgot. :-( > > > I don't see xhci-plat.c doing that, I wonder if it needs it too. > > > > I'm not well versed about the details and the rules here. So my fix could be > > a hack, though it does seem the right thing to do. > > > > I wonder why the power core doesn't handle this transparently.. > > Initially, we didn't want the PM core to do this automatically because > we thought some devices might want to remain runtime-suspended > following a system resume, and only the device driver would know what > to do. > > Raphael, now that we have the direct_complete mechanism, can we revisit > this? Should the PM core automatically call pm_runtime_set_active() if > dev->power.direct_complete isn't set? Perhaps in device_resume_early() > prior to the pm_runtime_enable() call? > > It's possible we discussed this and decided against it at the time when > direct_complete was added, but if so I don't remember what was said. Me neither. :-) That said complexity has grown since then and there are the DPM_FLAG_SMART_SUSPEND and DPM_FLAG_LEAVE_SUSPENDED flags that can be used to control that behavior to some extent. Setting DPM_FLAG_SMART_SUSPEND alone, in particular, causes pm_runtime_set_active() to be called at the noirq stage of device resume either by the core or by bus types (e.g. PCI) etc. It looks like ohci-platform might use DPM_FLAG_SMART_SUSPEND, but I need to take a closer look at that (possibly later this week). Cheers! > > > diff --git a/drivers/usb/host/ohci-platform.c b/drivers/usb/host/ohci-platform.c > > index 7addfc2cbadc..eb92c8092fae 100644 > > --- a/drivers/usb/host/ohci-platform.c > > +++ b/drivers/usb/host/ohci-platform.c > > @@ -299,6 +299,10 @@ static int ohci_platform_resume(struct device *dev) > > } > > > > ohci_resume(hcd, false); > > + > > + pm_runtime_disable(dev); > > + pm_runtime_set_active(dev); > > + pm_runtime_enable(dev); > > return 0; > > } > > #endif /* CONFIG_PM_SLEEP */ > > > > > > Thanks > > > > -- > > Qais Yousef > >
