On Thu, 14 Nov 2013, Ulf Hansson wrote: > > If you want a driver to do the same thing for runtime PM and system > > suspend/resume, point its .suspend_late() and .runtime_suspend() to the > > same routine and analogously for .runtime_resume() and .resume_early() > > (that may not work for PCI, though, because of the _noirq stuff, but that's > > the PCI bus type issue). > > When your .suspend_late callback gets called, your device may be > either active or inactive from runtime PM point of view. Just pointing > the .suspend_late callback to the .runtime_suspend callback, simply > wont work. > > That would mean we might end up in trying to inactivate an already > inactivated device, which I doubt is a good thing.:-) Some additional > code will be needed to track the "runtime state" and to act > accordingly. This is what drivers already tries to handle as of today, > though so far mostly from their .suspend callbacks I believe. You could write a "generic" suspend_late routine that would invoke the driver's runtime_suspend routine if the device's runtime PM status was RPM_ACTIVE. > > Of course, the assumption behind .runtime_suspend() and .runtime_resume() is > > that they will be run when the device is not in use, while system suspend > > may actually happen when the device *is* in use and .suspend() should take > > care of that if necessary. So you may need .suspend() anyway. > > > > One important property of system suspend is that it can happen at any time > > and that's why the .suspend() and .resume() callbacks are needed (and this > > also means that they can't be the same as .runtime_suspend() and > > .runtime_resume() in general). > > I see your point and in most cases you are right. But, I am also sure > that quite many drivers should be able to cope with only runtime PM > callbacks. I have collected a bunch of examples that I can share, if > you are interested? All those drivers should be able to utilize this "generic" suspend_late routine. Alan Stern -- 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
