On Tue, 11 Jun 2019, Felipe Balbi wrote: > >> >> > So for "severe" issues, yes, we should do this, but perhaps not for > >> >> > all > >> >> > of the "normal" things we see when a device is yanked out of the > >> >> > system > >> >> > and the like. > >> >> > >> >> Then what counts as a "severe" issue? Anything besides enumeration > >> >> failure? > >> > > >> > Not that I can think of at the moment, other than the other recently > >> > added KOBJ_CHANGE issue. I'm sure we have other "hard failure" issues > >> > in the USB stack that people will want exposed over time. > >> > >> From an XHCI standpoint, Transaction Errors might be one thing. They > >> happen rarely and are a strong indication that the bus itself is > >> bad. Either bad cable, misbehaving PHYs, improper power management, etc. > > > > Don't you also get transaction errors if the user unplugs a device in > > the middle of a transfer? That's not the sort of thing we want to sent > > notifications about. > > Mathias, do we get Transaction Error if user removes cable during a > transfer? I thought we would just get Port Status Change with CC bit > cleared, no?
Even if xHCI doesn't give Transaction Errors when a cable is unplugged during a transfer, other host controllers do. Sometimes quite a lot -- they continue to occur until the kernel polls the parent hub's interrupt ep and learns that the port is disconnected, which can take up to 250 ms. Alan Stern
