[coreboot] USB tick in SMM?

[David Hubbard]

On Tue, Apr 29, 2014 at 11:36 AM, ron minnich <rminnich at gmail.com> wrote:

> Anybody out there know typical numbers for the timer tick if USB is
> active as part of SMM?
>
> I just heard one number for one product line, 8 HZ. We're seeing a
> mysterious 18 HZ tick on one system. Any other numbers people know?
>

18.2 Hz is legacy stuff,
http://wiki.osdev.org/Programmable_Interval_Timer- but the particulars
of an SMM implementation might just as well be a
copy-paste error, for all I know.

An OHCI driver might use a timer tick to recover after a timeout. The USB
spec doesn't specify all the timeouts, though multiples of 100ms are common
(so a ~10HZ timer might be useful).

Hope that helps,
David
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