On Wed, 29 Jan 2020, Marco Felsch wrote: > Hi Alan, Rafael, Greg, > > long story short: I want to disable a usb-port completely during suspend You're talking about what happens during a full system suspend, right? > because it isn't needed and we need to save energy, because is a 32bit ARM > (OF-based) handheld device. I use the port to connect a usb-ethernet > dongle (all needed drivers are builtin no modules) which is needed for > the NFS. The usb-ethernet dongle supports the persist setting because it > does a hw-reset during resume anyway. > > So what I did is: > 1) Set the persist bit for the usb device > 2) Set the control to auto for the usb device > 3) Unset the pm_qos_no_power_off flag for the usb-port > > But the port gets not disabled. I debugged it and found a problem in > usb_port_suspend() logic [1] and the generic PM-framework more precisely > the dpm mechanism. The usbcore does the correct pm_runtime counting but > the call [2] don't trigger the usb_port_runtime_suspend() [3] because > the dpm enables all runtime-pm device before the shutdown is executed. That's right; it's supposed to work that way. We don't want runtime suspend kicking in and messing things up during a system suspend. > IMHO both subsystem behaviours are correct and I don't know the > _correct_ fix, therefore I wrote this email. The correct fix is to add support for system suspend to the USB port driver. Currently it only supports runtime suspend, as you can see from the definition of usb_port_pm_ops in port.c. Alan Stern > As far as I understood it all non-ACPI platforms are affected. > > Regards, > Marco > > [1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/usb/core/hub.c?h=v5.5#n3238 > [2] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/usb/core/hub.c?h=v5.5#n3328 > [3] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/usb/core/port.c?h=v5.5#n247
