On Fri, 28 Jun 2013, Roger Quadros wrote: > > That's not what I meant. Never mind the pinctrl; I was asking about > > the EHCI controller itself. Under what circumstances does the > > controller assert its wakeup signal? And how do you tell it to stop > > asserting that signal? > > I believe this would be through the EHCI Interrupt enable register (USBINTR). > I'm not aware of any other mechanism. That's strange, because ehci_suspend() sets the intr_enable register to 0. So how do you ever get any wakeup interrupts at all? > Right. It seems the external hub has signaled remote wakeup but the kernel doesn't > resume the root hub's port it is connected to. > > By observing the detailed logs below you can see that the root hub does not generate > an INTerrupt transaction to notify the port status change event. I've captured the pstatus > and GetPortStatus info as well. We don't need an interrupt. The driver is supposed to detect the remote wakeup sent by the external hub all by itself. > Failing case > ------------ > > [ 16.108032] usb usb1: usb auto-resume > [ 16.108062] ehci-omap 48064800.ehci: resume root hub > [ 16.108154] hub 1-0:1.0: hub_resume > [ 16.108398] ehci_hub_control GetPortStatus, port 1 temp = 0x1000 > [ 16.108459] ehci_hub_control GetPortStatus, port 2 temp = 0x14c5 Here's where we should detect it. Look at the GetPortStatus case in ehci_hub_control(); the PORT_RESUME bit (0x0040) is set in temp, so the "Remote Wakeup received?" code should run. In particular, these lines should run: /* resume signaling for 20 msec */ ehci->reset_done[wIndex] = jiffies + msecs_to_jiffies(20); usb_hcd_start_port_resume(&hcd->self, wIndex); /* check the port again */ mod_timer(&ehci_to_hcd(ehci)->rh_timer, ehci->reset_done[wIndex]); Therefore 20 ms later, around timestamp 16.128459, ehci_hub_status_data() should have been called. At that time, the root-hub port should have been fully resumed. > [ 16.108551] hub 1-0:1.0: port 2: status 0507 change 0000 > [ 16.108612] ehci_hub_control GetPortStatus, port 3 temp = 0x1000 > [ 16.108642] hub 1-0:1.0: hub_activate submitting urb > [ 16.109222] ehci_irq port 3 pstatus 0x1000 > [ 16.109222] ehci_irq port 2 pstatus 0x14c5 > [ 16.109252] ehci_irq port 1 pstatus 0x1000 > [ 16.109374] hub 1-0:1.0: state 7 ports 3 chg 0000 evt 0000 But apparently nothing happened. Why not? Did the rh_timer get reset? Maybe you can find out what went wrong. (Hmmm, we seem to be missing a set_bit(wIndex, &ehci->resuming_ports); line in there...) > > Also, why do you need omap->initialized? Do you think you might get a > > wakeup interrupt before the controller has been fully set up? I don't > > see how you could, given the pm_runtime_get_sync() call in the probe > > routine. > > > > During probe we need to runtime_resume the device before usb_add_hcd() since the > controller clocks must be enabled before any registers are accessed. > However, we cannot call ehci_resume() before usb_add_hcd(). So to prevent this > chicken & egg situation, I've used the omap->initialized flag. It only indicates that > the ehci structures are initialized and we can call ehci_resume/suspend(). Ah, yes. Other subsystems, such as PCI, face exactly the same problem. You probably shouldn't call it "initialized", though, because the same issue arises in ehci_hcd_omap_remove() -- the pm_runtime_put_sync() there would end up calling ehci_suspend() after usb_remove_hcd(). "bound" or "started" would be better names. Alan Stern -- 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
