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SubjectRe: ehci-hcd affects hda speed
Date
On Saturday 15 March 2008, Lev A. Melnikovsky wrote:
> Particularly, what does "MAC turn around
> time" stand for with respect to EHCI? I would appreciate some reference,
> thanks.

Blame VIA for that one. Notice how their descriptions of the
fields in that register don't even mention a MAC. :)

But the relevant bit is the "sleep time" and that's described
in the EHCI specification. It basically means how long it waits,
after noticing a "no work for me" async schedule ring, before
scanning that schedule again. It seems your system had that
set to just 1 usec, meaning it would hardly give anything else
a chance to get onto the PCI bus. That's probably why the EHCI
spec uses a value of 10 usec: basic fairness.

- Dave




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