On Tue, 10 Apr 2018, Jonathan Gray wrote: > On Sat, Apr 07, 2018 at 01:35:31PM +0200, Stefan Fritsch wrote: > > On Fri, 6 Apr 2018, Jonathan Gray wrote: > > > > > On Thu, Apr 05, 2018 at 09:57:23PM +0200, Stefan Fritsch wrote: > > > > Add another magic 1ms delay that seems to help with some remaining > > > > issues on an HP elitebook 820 G3 with i219LM. A printf() at the same > > > > place helps, too. > > > > > > Could you explain what the problem here was and why this place was > > > chosen to add the delay? > > > > The problems fixed by patches 1-6 were that there were these kinds of > > errors > > > > em0: Hardware Initialization Failed > > em0: Unable to initialize the hardware > > > > either during em_attach (in this case em0 would simply not be available in > > ifconfig) or during ifconfig up. The problems only appeared if there was > > no link (or no cable plugged in) during boot or during resume. > > > > The fixes 1 to 5 made the problem appear much less often, but it still > > appeared sometimes. I had some printfs added and I have never seen the > > problem with the printf present. In the end I traced the "fix" to the > > single printf at this exact location and I replaced it with a delay. > > > > We added Patch 6 (the E1000_TARC0_CB_MULTIQ_2_REQ erratum) later, to fix > > different problems with watchdog timeouts that were only recoverable by a > > reboot, when pulling the cable or when the link was flaky. > > If you have the HP machine that triggers the problem it should be possible > to find which register write the delay is needed after?
That should be possible, yes. I don't know when I will have the time for that, though. > > > > > > > > > > --- > > > > sys/dev/pci/if_em_hw.c | 2 ++ > > > > 1 file changed, 2 insertions(+) > > > > > > > > diff --git sys/dev/pci/if_em_hw.c sys/dev/pci/if_em_hw.c > > > > index 7709a4c5805..d122e727875 100644 > > > > --- sys/dev/pci/if_em_hw.c > > > > +++ sys/dev/pci/if_em_hw.c > > > > @@ -1493,6 +1493,8 @@ em_init_hw(struct em_hw *hw) > > > > /* Set the media type and TBI compatibility */ > > > > em_set_media_type(hw); > > > > > > > > + /* Magic delay that improves problems with i219LM on HP > > > > Elitebook */ > > > > + msec_delay(1); > > > > /* Must be called after em_set_media_type because media_type is > > > > used */ > > > > em_initialize_hardware_bits(hw); > > > > > > > > -- > > > > 2.13.0 > > > > > > > > > > >
