Messages in this thread | | | From | David Brownell <> | Subject | Re: ehci-hcd affects hda speed | Date | Mon, 17 Mar 2008 13:06:52 -0800 |
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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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