Date: Tue, 27 Oct 2020 09:02:59 +0100 From: Hans Petter Selasky <hps@selasky.org> To: Mark Millard <marklmi@yahoo.com>, freebsd-arm <freebsd-arm@freebsd.org> Subject: Re: A RPi4 xHCI VL805 problem that needs to be avoided: "xhci: quirks: add link TRB quirk for VL805" Message-ID: <0b70dbc4-f118-29bc-d814-8fc0a5669382@selasky.org> In-Reply-To: <FD9CBF82-36D5-4650-8F8C-FAE0688E6F68@yahoo.com> References: <FD9CBF82-36D5-4650-8F8C-FAE0688E6F68.ref@yahoo.com> <FD9CBF82-36D5-4650-8F8C-FAE0688E6F68@yahoo.com>
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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
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