A RPi4 xHCI VL805 problem that needs to be avoided: "xhci: quirks: add link TRB quirk for VL805"

[Hans Petter Selasky]

On 2020-10-27 00:58, Mark Millard via freebsd-arm wrote:
> https://github.com/raspberrypi/linux/pull/3929 reports:
> 
> QUOTE
> The VL805 controller can't cope with the TR Dequeue Pointer for an endpoint
> being set to a Link TRB. The hardware-maintained endpoint context ends up
> stuck at the address of the Link TRB, leading to erroneous ring expansion
> events whenever the enqueue pointer wraps to the dequeue position.
> 
> If the search for the end of the current TD and ring cycle state lands on
> a Link TRB, move to the next segment.
> END QUOTE
> 
> Also: Dealing with the link trb also toggling the ring cycle state
> is something to watch for according to the later notes.
> 

Is this an issue under FreeBSD too? Can it be reproduced?

--HPS