[vfio-users] Bus reset trouble with Titan-X
Alex Williamson
alex.williamson at redhat.com
Wed Oct 19 16:57:39 UTC 2016
On Wed, 19 Oct 2016 11:46:21 -0500
Kevin Vasko <kvasko at gmail.com> wrote:
> Alex,
>
> Thanks, but no luck.
>
> I ran :
>
> #:setpci -s 3:00.0 82.w=8:8
>
> checked
>
> #:lspci -vvvs 3:00.0
>
> MRL- was the same.
PresDet+ on the Changed: line was the thing we were looking for. MRL
is a retention latch specifically for hotplug capable slots.
> #: setpci -s 3:00.0 78.w=20:20
>
> checked:
>
> #: lspci -vvs 3:00.0
>
> MRL- was the same
>
>
> LnkSta: Speed 2.5GT/s, Width x0, TrErr- Train- SlotClk- DLActive- BWMgmt-
> ABWMgmt-
>
> SltSta: Status: AttnBtn- PowerFlt- MRL- CmdCplt- PresDet+ Interlock-
> Changed: MRL- PresDet+ LinkState-
>
> Just for my own knowledge what does "retrain" mean? I assume resetting the
> bus and it reconnecting successfully?
Retraining triggers a re-sync of the link width and speed parameters,
think of it like kicking an Ethernet connection to renegotiate
10/100/1000Mbps speeds, a similar thing happens between a device and
the downstream port that it's connected to to determine the link
parameters. Thanks,
Alex
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