On Wed, Jan 08, 2025, Thinh Nguyen wrote: > On Mon, Jan 06, 2025, Ray Chi wrote: > > When the system begins to enter suspend mode, dwc3_suspend() is called > > by PM suspend. There is a problem that if someone interrupt the system > > suspend process between dwc3_suspend() and pm_suspend() of its parent > > device, PM suspend will be canceled and attempt to resume suspended > > devices so that dwc3_resume() will be called. However, dwc3 and its > > parent device (like the power domain or glue driver) may already be > > suspended by runtime PM in fact. If this sutiation happened, the > > pm_runtime_set_active() in dwc3_resume() will return an error since > > parent device was suspended. This can lead to unexpected behavior if > > DWC3 proceeds to execute dwc3_resume_common(). > > > > EX. > > RPM suspend: ... -> dwc3_runtime_suspend() > > -> rpm_suspend() of parent device > > ... > > PM suspend: ... -> dwc3_suspend() -> pm_suspend of parent device > > ^ interrupt, so resume suspended device > > ... <- dwc3_resume() <-/ > > ^ pm_runtime_set_active() returns error > > > > To prevent the problem, this commit will skip dwc3_resume_common() and > > return the error if pm_runtime_set_active() fails. > > > So, if the device is runtime suspended, we prevent any interrupt during > system suspend? Any way we can keep the same behavior and allow PM > interruption as when there's no runtime suspend. > Actually, I misread, the interruption is still there. Just the resume is prevented. Looks good to me. Acked-by: Thinh Nguyen <Thinh.Nguyen@xxxxxxxxxxxx> Thanks, Thinh
