Re: [REGRESSION][BISECTED] "xHCI host controller not responding, assume dead" on stable kernel > 6.8.7

Mika Westerberg
2024-05-23T04:45:12Z

On Wed, May 22, 2024 at 10:19:51AM -0500, Mario Limonciello wrote:
> On 5/22/2024 09:41, Gia wrote:
> > Now this is odd...
> >
> > I've tested another cable - a very short one used with a Gen3 nvme
> > enclosure that I'm sure it's working - and I got Gen2 20 Gbps. I also
> > have tested this on Windows 11 and I still just got a Gen2 connection.
> >
> > I was almost sure it was caused by a bad USB4 implementation by the PC
> > manufacturer, then I tried to connect a Thunderbolt 3 disk enclosure
> > via daisy chain to the Caldigit dock and I got the full Gen3 40 Gbps
> > connection! See the attached picture.
> >
>
> I suspect you can't actually get Gen 3 performance in this configuration.
> IIUC you should still be limited by the uplink to the host.

One "explanation" could be that the distance from the SoC to the Type-C
connector is relatively long which would require a retimer to get the
Gen3 speeds.