On 11 August 2016 at 16:44, Peter Chen <hzpeterchen@xxxxxxxxx> wrote: > 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. OK. I try to look at it. Thanks. > > -- > > Best Regards, > Peter Chen -- Baolin.wang Best Regards -- 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
