Re: A RPi4 xHCI VL805 problem that needs to be avoided: "xhci: quirks: add link TRB quirk for VL805"
Mark Millard via freebsd-arm <[email protected]>
| Newsgroups | gmane.os.freebsd.devel.arm |
|---|---|
| Message-ID | <[email protected]> |
On 2020-Oct-27, at 01:02, Hans Petter Selasky <hps at selasky.org> wrote: > 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? > I've no clue how to set up a test to see if FreeBSD can set the TR Dequeue Pointer for an end point to a Link TRB vs. showing that it somehow avoids doing that. I reported it on just the basis of the claim that the controller mishandles the condition if it occurs. === Mark Millard marklmi at yahoo.com ( dsl-only.net went away in early 2018-Mar) _______________________________________________ [email protected] mailing list https://lists.freebsd.org/mailman/listinfo/freebsd-arm To unsubscribe, send any mail to "[email protected]"