On 22-01-07 15:58:26, Frank Li wrote: > Mathias Nyman > > Recently we found a crash at xhci_disable_hub_port_wake when system suspend if enable remote wake up. > > Basial flow is. > > 1. run time suspend call xhci_suspend, xhci parent devices gate the clock. > 2. echo mem >/sys/power/state, system _device_suspend call xhci_suspend > 3. xhci_suspend call xhci_disable_hub_port_wake, which access register, but clock already gated by run time pm. > > Why find this issue now, that is because previous power domain driver will call run time resume before it. But the below commit remove it. > > c1df456d0f06eb9275c1cd4c66548fc5738ea428 > Author: Ulf Hansson ulf.hansson@xxxxxxxxxx > Date: Thu Mar 4 20:28:43 2021 +0100 > > PM: domains: Don't runtime resume devices at genpd_prepare() > > > > According to HCD_FLAG_HW_ACCESSIBLE logic, xhci should not access hardware when second time call xhci_suspend without call xhci_resume. > > xhci_disable_hub_port_wake(xhci, &xhci->usb3_rhub, do_wakeup); > xhci_disable_hub_port_wake(xhci, &xhci->usb2_rhub, do_wakeup); > > if (!HCD_HW_ACCESSIBLE(hcd)) > return 0; > > ..... > clear_bit(HCD_FLAG_HW_ACCESSIBLE, &hcd->flags); > clear_bit(HCD_FLAG_HW_ACCESSIBLE, &xhci->shared_hcd->flags); > > I am not sure if it is safe to move xhci_disable_hub_port_wake after HCD_HW_ACCESSIBLE check, Or need add additional run_time_resume before it. Frank, I prefer adding runtime resume at xhci-plat.c like below, let's see what Mathias says. diff --git a/drivers/usb/host/xhci-plat.c b/drivers/usb/host/xhci-plat.c index c1edcc9b13ce..47a5a10381a7 100644 --- a/drivers/usb/host/xhci-plat.c +++ b/drivers/usb/host/xhci-plat.c @@ -440,6 +440,9 @@ static int __maybe_unused xhci_plat_suspend(struct device *dev) ret = xhci_priv_suspend_quirk(hcd); if (ret) return ret; + + if (pm_runtime_suspended(dev)) + pm_runtime_resume(dev); /* * xhci_suspend() needs `do_wakeup` to know whether host is allowed * to do wakeup during suspend. -- Thanks, Peter Chen
