On Wed, 7 Nov 2012, Rafael J. Wysocki wrote: > > The PCI subsystem assumes that > > driverless devices are not in use, so they are disabled for runtime PM > > and marked as suspended. This is not appropriate for VGA devices, > > which can indeed be used without a driver. > > > > I'm not sure what the best solution is. Maybe we should Ying's > > proposal a step farther: > > > > Make pm_runtime_set_suspended() fail if runtime PM is > > forbidden. > > > > Make pm_runtime_forbid() call pm_runtime_set_active() > > (and do a runtime resume of the parent) if disable_depth > 0. > > I'd prefer this one.
That wasn't meant to be a choice. The first item is close to what the original patch did; I was suggesting that we should adopt all three items. If you adopt the second item but not the first then things won't work when a driver is removed after power/control is set to "on". > The callers of pm_runtime_forbid() may actually > reasonably expect something like this to happen. > > > Make the PCI runtime-idle routine call > > pm_runtime_set_suspended() if disable_depth > 0. Or maybe > > do this for all devices, in the runtime PM core. > > That would mean calling it on every call to pm_runtime_put() and friends > which seems to be a bit wasteful. Not on every call; only when disable_depth > 0. We don't expect to see idle calls very often under those circumstances. Alan Stern -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
