First, sorry for the delayed response. Frans has just reminded me about this thread. On Tuesday 24 March 2009, Alan Stern wrote: > On Mon, 23 Mar 2009, Frans Pop wrote: > > > > Or do you think maybe it would be better to move this test up into the > > > PM core? After all, other subsystems will face the same issue. I > > > think that would be the best approach. Yes? > > > > I did look at that option, but implementing it in the USB subsystem seemed > > more logical to me, for example as other subsystems possibly would want to > > display an info message. > > They still can... > > > And is -ENODEV safe to ignore in all cases? Would there be other errors that > > should be ignored too? > > In general, the PM core ignores _all_ errors during resume -- in the > sense that it doesn't try to recover from them or do anything to handle > them. All it does is put a message in the log. > > So your question becomes: For which errors should a message be added to > the system log? The most logical answer seems to be that we want an > error message whenever something bad or unexpected occurs. > > Removal of a hot-unpluggable device isn't really bad or unexpected. > Removal of a non-hot-unpluggable device might be bad, but on the other > hand the system isn't really "hot" while it is suspended. Besides, the > appropriate subsystem can print an error message. Furthermore the > kernel can't easily tell which devices are hot-unpluggable and which > aren't. > > Anything else amounts to failure resuming a device that still exists. > As such, it probably deserves an error message. Returning 0 from usb_external_resume_device() if the device is not present any more doesn't seem wrong. It's not really an error condition, IMO, because it's rather normal that the devices may be removed while suspended. OTOH, I don't think we can ignore -ENODEV universally in the core, because its meaning may depend on the bus type. For example, for PCI it sometimes means a hardware problem has occured (other than the device being not present any more). > > if Rafael would be happy with a generic test for -ENODEV, it could be done. > > If not, maybe some other special error code would need to be used but then > > you'd still need to test in the subsystem to set that error. > > Disadvantage is also that it would make resume_device() and related PM > > driver core functions quite a bit less clean than they currently are. > > > > Implementing the test in USB was quite a bit simpler (for me at least ;-) > > We should get Rafael's opinion. I'd vote in favor of the Frans' patch, at least for now. So, Frans, please resubmit with the changelog modified as requested by Alan. Best, Rafael _______________________________________________ linux-pm mailing list linux-pm@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/linux-pm
