Hi, Alan Stern <stern@xxxxxxxxxxxxxxxxxxx> writes: >> 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. 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? -- balbi
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