Subject: Re: [PATCH net-next V3 1/2] igb: add PTP Hardware Clock code

From: Richard Cochran <[email-masked]>
Date: Tue, 10 Jan 2012 10:33:49 +0100

On Tue, Jan 10, 2012 at 09:44:50AM +0100, Richard Cochran wrote:
> On Mon, Jan 09, 2012 at 05:42:20PM +0000, Keller, Jacob E wrote:
> 
> > Is there a reason for not using the timecounter structure from the
> > kernel? It is a layer beneath the timecompare code which is meant to
> > handle this condition. As far as I can tell this issue is solved in
> > the timecounter code. If it is not, then that should be a bug in the
> > timecounter cyclecounter code. I don't know if this issue occurs in
> > the timecounter structure because it handles the ns conversion
> > differently.
> 
> My only reason is that I am not sure that the timecounter code really
> does what we need.  It might well work.  Consider, though, that the
> 82580 register does not overflow in the usual way. The upper 24 bits
> are always zero.
> 
> What I wrote does the right thing, I think.  However, duplicated
> effort is always bad, so can you show me how to change it?

I took a brief look, and I think the timecounter idea might work.
Later this week I'll try it out if I can.

Thanks,
Richard