Ryan: You should present your questions to the maintainer of the kernel's Power Management subsystem, Rafael Wysocki (added to the To: list for this email). Alan Stern On Wed, Aug 27, 2025 at 10:09:10PM +0800, ryan zhou wrote: > Hi Roy, > Thank you for reviewing my patch. > > > > Wouldn't the parent glue dev already resume before resuming the child dwc3? > > > No, in the following case, the parent device will not be reviewed > before resuming the child device. > Taking the 'imx8mp-dwc3' driver as an example. > Step 1.usb disconnect trigger: the child device dwc3 enter runtime > suspend state firstly, followed by > the parent device imx8mp-dwc3 enters runtime suspend > flow:dwc3_runtime_suspend->dwc3_imx8mp_runtime_suspend > Step2.system deep trigger:consistent with the runtime suspend flow, > child enters pm suspend and followed > by parent > flow: dwc3_pm_suspend->dwc3_imx8mp_pm_suspend > Step3: After dwc3_pm_suspend, and before dwc3_imx8mp_pm_suspend, a > task terminated the system suspend process > . The system will resume from the checkpoint, and resume devices in > the suspended state in the reverse > of pm suspend, but excluding the parent device imx8mp-dwc3 since it > did not execute the suspend process. > > > > >Why would 'runtime PM trying to activate child device xxx.dwc3 but parent is not active' happen in the first place? > > > Following the above analysis, dwc3_resume calls > pm_runtime_set_active(dev), it checks the > parent.power->runtime_status is not RPM_ACTIVE and outputs the error log. > > > > >What is the glue driver that's being used here? Knowing what's being done in the glue driver pm callbacks > >would help in understanding the issue. > > > Refer to the driver 'dwc3-imx8mp.c' please, maybe you could help me > find a better solution. > > > Thanks, > ryan > > Roy Luo <royluo@xxxxxxxxxx> 于2025年8月27日周三 02:38写道： > > > > On Tue, Aug 26, 2025 at 8:12 AM Ryan Zhou <ryanzhou54@xxxxxxxxx> wrote: > > > > > > Issue description: > > > The parent device dwc3_glue has runtime PM enabled and is in the > > > runtime suspended state. The system enters the deep sleep process > > > but is interrupted by another task. When resuming dwc3, > > > console outputs the log 'runtime PM trying to activate child device > > > xxx.dwc3 but parent is not active'. > > > > > > > Wouldn't the parent glue dev already resume before resuming the child dwc3? > > Why would 'runtime PM trying to activate child device xxx.dwc3 but parent is > > not active' happen in the first place? > > What is the glue driver that's being used here? Knowing what's being done in > > the glue driver pm callbacks would help in understanding the issue. > > > > Regards, > > Roy >
