>> Is 3rd situation you mentioned above the function will be called is
>> hcd->bus_suspend?
>
> hcd->bus_suspend will be called first, and shortly afterward
> ehci->suspend will be called (if this is an EHCI controller).
>
>> > Fourthly, you should realize that "controller itself will also be put
>> > into runtime suspend" means the controller itself will be put into
>> > runtime suspend.
>> is 4th situation you mentioned above the function will be called is
>> ehci_suspend, (take ehci for example)?
>
> Yes.
after tracing the source, I only can find the ehci_suspend is called
when system hibernate/suspend.
rpm_suspend use below method to find out suspend callback
if (dev->pm_domain)
callback = dev->pm_domain->ops.runtime_suspend;
else if (dev->type && dev->type->pm)
callback = dev->type->pm->runtime_suspend;
else if (dev->class && dev->class->pm)
callback = dev->class->pm->runtime_suspend;
else if (dev->bus && dev->bus->pm)
callback = dev->bus->pm->runtime_suspend;
else
callback = NULL;
ehci_suspend doesn't register any one of above function.
>
>> but ehci_supend is called when system is going to suspend/hibernate,
>> or it will be called even in runtime suspend?
>
> Both.
>
>> BTW, when I turn off the led on the keyboard, the keyboard can
>> successfully go to runtime suspend.
>
> Good.
>
>> Would you mind to let us know how you find out the problem from mon files?
>> Is it due there is no remote wake control message on the mon file?
>
> The usbmon trace showed that the interrupt URB for one of the HID
> interfaces was cancelled (indicating that the interface had been
> suspended) but the interrupt URB for the other HID interface was not
> cancelled (indicating that the interface had failed to suspend).
>
> Reading the source code for the usbhid driver showed that there are
> only a few reasons for failing to suspend an interface, and one of
> those reasons was if an LED was illuminated.
Sincerely appreciate your kind help,
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