On Tue, Jul 21, 2020 at 09:23:14PM +0530, Vaibhav Gupta wrote: > Hello, > Currently I am working on removing legacy power management .suspend() and > .resume() callbacks from PCI subsystem. The updates aim to give power management > control to PCI core and let drivers do the only device-specific jobs without > using any PCI helper functions. > > I was wondering if similar changes can be applied to the USB subsystem? > I explored and found that .suspend() in USB drivers also accept the pm_message_t > type argument. > Also, .suspend() and .resume() in usb drivers, accept "struct usb_interface *" > type argument which seems similar to PCI legacy drivers accepting > "struct pci_dev*" type. > > Moreover, "struct usb_device_driver" seems analogous to "struct pci_driver" as > it also has .suspend() and .resume() callback. Also, it has a bitfield > "generic_subclass:1" which is described as, " @generic_subclass: if set to 1, > the generic USB driver's probe, disconnect, resume and suspend functions will be > called in addition to the driver's own, so this part of the setup does not need > to be replicated. " > > So the generic PM, talked about in USB drivers, is similar to PCI one? I don't know what you mean by "the generic PM". IMO, overall USB power management is pretty similar to the arrangement in PCI, although with less legacy stuff remaining. > The > non-generic PM in USB is similar to legacy PM in PCI? No, I don't think so, although it's hard to give an exact answer to such an imprecise question. What sort of thing would make USB PM similar to legacy PCI PM? > A similar update for the USB subsystem is possible? I think you'll find that the power management in USB drivers already does only device-specific things, with overall control remaining in the USB core. Maybe if you came up with some more specific examples of what you are thinking of, I could give better answers. Alan Stern
