On 03/25/20 22:28, Rafael J. Wysocki wrote: > 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). Okay I take it this was root caused correctly and now it's a question of which is a better fix. Thanks! -- Qais Yousef
