On Thu, Aug 11, 2016 at 04:41:27PM +0800, Baolin Wang wrote: > >> >> > >> >> OK. But that is a real problem. It will pm_runtime_resume() falied > >> >> (issued in choose_wakeup()), cause usb controller has powered-off and > >> >> xHCI controller has suspended and we have no method to notify the user > >> >> to power-on USB controller. Any good suggestion to solve this, Alan > >> >> and Peter? Thanks. > >> >> > >> > > >> > Maybe you can show us the call stack why pm_runtime_resume has failed > >> > at your environment. > >> > >> OK. I try to explain it at below: > >> > >> For example: No slave attached----> usb interface runtime suspend > >> ----> usb device runtime suspend (routine is: > >> usb_suspend_device()--->generic_suspend() --> hcd_bus_suspend()--> > >> xhci_bus_suspend()) -----> xhci_ suspend() -----> power off usb > >> controller. After that if the system wants to enter suspend state, > >> then it also will issue usb_dev_suspend(), then the > >> pm_runtime_resume() function (issued in choose_wakeup() function) will > >> return -ESHUTDOWN due to xhci has been suspend and hardware is not accessible. > >> > >> We issue the pm_runtime_resume() function routine: usb_resume_device() > >> ----> generic_resume() ----> hcd_bus_resume() ---> xhci_bus_resume(), > >> but now xHCI is not accessible due to xhci_suspend() is issued and USB > >> controller is power off when no slave attached. That is why > >> pm_runtime_resume failed. > >> > > > > What host controller driver you are using? Assume you are using > > xhci-plat.c. The problem for you is this driver does not implement > > Yes. I use xhci-plat.c. > > > runtime pm operations, so the flag HCD_FLAG_HW_ACCESSIBLE is not set. > > Maybe Robert's patch is a good start for you [1] > > > > [1] http://www.spinics.net/lists/linux-usb/msg144602.html > > OK. Maybe I need to implement the runtime PM callbacks for xhci-plat, right? > I think so. -- Best Regards, Peter Chen -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
