On Fri, 7 Jun 2019, Felipe Balbi wrote: > Hi, > > Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> writes: > > On Thu, Jun 06, 2019 at 10:55:24AM -0400, Alan Stern wrote: > >> On Thu, 6 Jun 2019, Greg Kroah-Hartman wrote: > >> > >> > On Thu, Jun 06, 2019 at 10:24:18AM -0400, Alan Stern wrote: > >> > > On Thu, 6 Jun 2019, David Howells wrote: > >> > > > >> > > > Add a USB subsystem notification mechanism whereby notifications about > >> > > > hardware events such as device connection, disconnection, reset and I/O > >> > > > errors, can be reported to a monitoring process asynchronously. > >> > > > >> > > USB I/O errors covers an awfully large and vague field. Do we really > >> > > want to include them? I'm doubtful. > >> > > >> > See the other patch on the linux-usb list that wanted to start adding > >> > KOBJ_CHANGE notifications about USB "i/o errors". > >> > >> That patch wanted to add notifications only for enumeration failures > >> (assuming you're talking about the patch from Eugeniu Rosca), not I/O > >> errors in general. > > > > Yes, sorry, I was thinking that as a "I/O failed in enumeration" :) > > > >> > 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. Alan Stern
