[SeaBIOS] [PATCH 03/16] usb-uhci: fix race against host controller
Paolo Bonzini
pbonzini at redhat.com
Thu Nov 17 09:02:28 CET 2011
On 11/17/2011 05:53 AM, Kevin O'Connor wrote:
> Interesting. Good catch! If I understand this correctly, the issue
> occurs because all TDs being complete doesn't guarentee that the QH is
> complete, and thus the next transfer races with the controller on the
> QH update.
Yep.
> Can't the code just use wait_pipe() at the end to eliminate the race?
Yes, that's correct. The previous call to usb_send_bulk guarantees that
the QH is quiescent. It still works (tested with 15 consecutive boots,
usually it fails in 2-3).
I'll reply to each modified individual patch with the v2, there's just a
handful of them.
Paolo
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