Re: [Linuxptp-users] Polling ptp clock not allowed?

[Keller, J. E <jac...@in...>]

On Thu, 2016-02-25 at 15:26 +0100, frank wrote:
> 
> On 02/25/2016 09:01 AM, frank wrote:
> > On 02/24/2016 06:23 PM, Keller, Jacob E wrote:
> > > > -----Original Message-----
> > > > Finally a collegue used the patch below and the problem
> > > > vanished(above
> > > > test code did run a long time),
> > > >  however it is unclear if the timestamps produced are still
> > > > 'correct' and
> > > > useful for ptp.
> > > > The fix still looks surprising..
> > > > 
> > > > kind regards
> > > >   Frank
> > > > 
> > > This is the work-around I was talking about below. I am surprised
> > > it is not in the 4.4 kernel?
> > > 
> > > This is a known hardware errata on some of the parts (I am not
> > > sure which ones) and it should have had the workaround pushed
> > > upstream. I am guessing your collegue got this from the out-of-
> > > tree driver on SourceForge
> > Hi,
> > 
> > no, we looked at the 4.4 Code and backported it to 3.19, but our
> > testcase still showed the problem.
> > Thought "this workaround cannot work if..." and created the patch
> > below
> > ourselfes.
> > Need to check sourceforge..
> > 
> Hm, the code in e1000e-3.3.3.tar.gz looks like the one in the 4.4
> kernel, so I suspect it will fail
> using the testcase too.
> 
> regards
>   Frank

How fast are you trying to read the clock in your test case? I suspect
that polling too rapidly may be what causes part of the issue?

I'm not certain, though. I don't know that particular hardware very
well.

Thanks,
Jake