On Thu, Aug 10, 2023 at 10:51:09PM +0000, Alexandru Gagniuc wrote: > On Thu, Aug 10, 2023 at 01:34:39PM -0400, Alan Stern wrote: > > I was thinking that the host controller driver's shutdown method might > > turn off power to all of the ports. > > > > For example, in the ehci-hcd driver, ehci_shutdown() calls > > ehci_silence_controller(), which calls ehci_turn_off_all_ports(). I > > don't know if xhci-hcd does anything similar. > > EHCI is a different beast. I don't think EHCI (USB2.0) has the U3 link state. USB-2 doesn't have link states, but it does have the notion of a downstream port being suspended, which is effectively the same as U3. > The equivalent for would be xhci_shutdown(). It makes a call to > usb_disable_xhci_ports() for XHCI_SPURIOUS_REBOOT quirk. As I have not > encountered it, I don't know how it will affect the link state of other ports. > The quirk appears to switch ports to EHCI mode, rather than turn off power. All right. The important point is that the patch works for your situation. I was just trying to find out how much thought you had given to the possibilities other people might face, if their systems aren't quite the same as yours. Alan Stern
