On Wed, Aug 30, 2017 at 10:07:59AM +0100, Ard Biesheuvel wrote: > On 30 August 2017 at 09:55, Mason <slash.tmp@xxxxxxx> wrote: > > On 30/08/2017 08:02, Greg Kroah-Hartman wrote: > > > >> To get back to the original issue here, the hardware seems to have died, > >> the driver stops talking to it, and all is good. The "regression" here > >> is that we now properly can determine that the hardware is crap. > > > > Before 4.12, when I unplugged my USB3 Flash drive, Linux would > > detect a few "Uncorrected Non-Fatal errors" via AER, but it was > > still possible to plug the drive back in. > > > > Since 4.12, once I unplug the drive, the whole USB3 card is marked > > as dead (all 4 ports), and I can no longer plug anything in (not even > > the USB2 drive that didn't have any issues, IIRC). > > > > It seems a bit premature to "mark as dead" something that remains > > functional, doesn't it? > > > > Disclaimer, there are many variables in this setup, and I've only > > tested a small fraction of the problem space: only one system, > > only one USB3 board, only one USB3 Flash drive. > > > > Please don't forget to mention that this is quirky hardware that > depends on BROKEN because it multiplexes MMIO and config space > accesses in the same memory window without any locking whatsoever > (which would be difficult to do in the first place because we don't > use accessors for MMIO in the kernel). > > So how likely is it that you are attempting to read from the xhci BAR > window while a config space access is in progress? Any way to > instrument this in your driver? Seriously? Ok, that's crap hardware, sorry, I don't feel bad at all here. You are going to have worse problems than just a single USB controller issue if that's your hardware design, go kick some hardware engineers for me please. good luck, you are on your own :( greg k-h
