Re: [v4l-dvb-maintainer] bttv driver questions

[Andy Walls <awalls@xxxxxxxxx>]

On Tue, 2008-08-26 at 19:20 -0700, Trent Piepho wrote:
> On Wed, 27 Aug 2008, Daniel [iso-8859-1] Glckner wrote:

> Isn't the latency timer in units of 250 ns, not PCI cycles?

Latency timer is in PCI clock cycles.  Most devices ignore the 3 least
significant bits of the setting (as allowed/suggested by the PCI spec),
making most latency timers as multiple of 8 PCI clock cycles.  

MIN_GNT and MAX_LAT are in units of 250 ns according to the PCI spec.
I'm assuming it's no coincidence that 8 PCI clock cycles = 8/33 MHZ =
242.4 ns or approximately 250 ns.

-Andy

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