Re: [PATCH v3 1/4] Add correlated clocksource deriving system time from an auxiliary clocksource

On Fri, Sep 04, 2015 at 10:11:22AM +0200, Richard Cochran wrote:

On Thu, Sep 03, 2015 at 11:20:37PM +0000, Hall, Christopher S wrote:

quoted

In addition to the network interface, ART will be used in the audio interface as well.
We need to support the case where an audio co-processor will control the audio device.
In this case, the get_ts() function supplied by the audio driver will be very slow
(several milliseconds) and the result will be out of date by some fraction of that 
amount.

Why does it take milliseconds to read one audio time stamp?

So what I suspect, but please correct me if I'm wrong Chris, is that a
DSP will buffer and process audio signals, and only later wake up the
main CPU.

So by the time the CPU is made aware of the data, it's 'old'.