Alan Stern <stern@xxxxxxxxxxxxxxxxxxx> writes: > On Wed, 6 Apr 2016, Bjørn Mork wrote: >> Alan Stern <stern@xxxxxxxxxxxxxxxxxxx> writes: >> > On Wed, 6 Apr 2016, Mathias Nyman wrote: >> > >> >> We don't want to runtime suspend a bus if there is an event pending. >> >> The roothub on a NEC uPD720200 host with a single USB3 device connected >> >> might go back to runtime suspend immediately after runtime resume as >> >> hub might not yet see any port changes in resume. >> >> >> >> Prevent this by checking if there is a unhandled event pending when >> >> calling runtime suspend. >> >> >> >> Cc: <stable@xxxxxxxxxxxxxxx> >> >> Tested-by: Mike Murdoch <main.haarp@xxxxxxxxx> >> >> Signed-off-by: Mathias Nyman <mathias.nyman@xxxxxxxxxxxxxxx> >> >> --- >> >> drivers/usb/host/xhci-hub.c | 6 ++++++ >> >> drivers/usb/host/xhci.c | 1 + >> >> 2 files changed, 7 insertions(+) >> >> >> >> diff --git a/drivers/usb/host/xhci-hub.c b/drivers/usb/host/xhci-hub.c >> >> index d61fcc4..7e8999a 100644 >> >> --- a/drivers/usb/host/xhci-hub.c >> >> +++ b/drivers/usb/host/xhci-hub.c >> >> @@ -1289,12 +1289,18 @@ int xhci_bus_suspend(struct usb_hcd *hcd) >> >> __le32 __iomem **port_array; >> >> struct xhci_bus_state *bus_state; >> >> unsigned long flags; >> >> + u32 status; >> >> >> >> max_ports = xhci_get_ports(hcd, &port_array); >> >> bus_state = &xhci->bus_state[hcd_index(hcd)]; >> >> >> >> spin_lock_irqsave(&xhci->lock, flags); >> >> >> >> + /* Don't suspend root hub if there's an event pending. */ >> >> + status = readl(&xhci->op_regs->status); >> >> + if (status & STS_EINT) >> >> + return -EBUSY; >> > >> > Does anybody else see a problem here? >> >> Like the EBUSY being propagated all the way to usb_suspend(), which is >> called on PMSG_HIBERNATE, PMSG_FREEZE and PMSG_SUSPEND? >> >> This will not only prevent runtime suspend, but also system suspend, >> wont it? Or did I miss something on the way? The call chain between >> the USB dev_pm_ops .suspend and xhci_bus_suspend() is quite long.. > > I was thinking of returning with a private spinlock held. No, I didn't see that. So I am happy to support Mathias' case by demonstrating that it wasn't *that* bloody obvious :) Bjørn -- 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
