Dear Chen Peter-B29397, > > > > No, that's not what I meant. Suppose there is no intermediate hub, > > > > only a 3G modem plugged directly into the root hub. The 3G modem > > > > does > > > > > > a runtime autosuspend, and then 2 seconds later sends a wakeup > > > > request. > > > > > > But the autosuspend timeout for the root hub is also 2 seconds, so > > > > the > > > > > > root hub suspends and the PHY goes into low-power mode at just the > > > > same > > > > > > time as when the wakeup request arrives. > > > > > > At your case, if we put PHY enters low power mode code at both > > > > ehci_hub_control > > > > > and ehci_bus_suspend, once 3G modem is suspended, the ehci_hub_control > > > (USB_PORT_FEAT_SUSPEND) will be called, then PHY enters low power mode > > > > code > > > > > will be called. roohub suspend (ehci_bus_suspend) will not set > > > > PORT_SUSPEND > > > > > at portsc and call PHY enters low power mode code again. > > > > Okay, I didn't realize you wanted to change the PHY state in > > ehci_hub_control also. You would power-down the PHY whenever every > > connected port was suspended, right? > > Oh, I have no experiences on multi-port system, all Freescale i.mx SoC > has only one port. I take it in case of multiport system, you'd have one phy per port ? Or are there phys that can operate with multiple ULPI inputs (aka. one phy per multiple CPU ports)? > > So consider this scenario instead. There is no intermediate hub, but > > there are two devices plugged directly into the root hub: a 3G modem > > and a flash drive. Is this possible on MXS? > > The 3G modem goes into runtime suspend. A minute > > later, the user unplugs the flash drive, and at that point the PHY is > > powered down. What's to prevent the modem from sending a wakeup signal > > at the same time? > > Modem can send wakeup at any time, yes, on multi-port system, the things > are different, it needs roothub handles one port's resume as well as > PHY is entering low power mode. Best regards, Marek Vasut -- 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
