netdev - Re: [Linuxptp-devel] strangeness

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Date:   Wed, 6 Mar 2019 18:06:55 -0500
From:   Paul Thomas <pthomas8589@...il.com>
To:     Harini Katakam <harinik@...inx.com>
Cc:     Richard Cochran <richardcochran@...il.com>,
        "linuxptp-devel@...ts.sourceforge.net" 
        <linuxptp-devel@...ts.sourceforge.net>, netdev@...r.kernel.org
Subject: Re: [Linuxptp-devel] strangeness

On Fri, Mar 1, 2019 at 1:24 AM Harini Katakam <harinik@...inx.com> wrote:
>
> +netdev
>
> Hi Paul,
> On Fri, Mar 1, 2019 at 12:29 AM Richard Cochran
> <richardcochran@...il.com> wrote:
> >
> > On Thu, Feb 28, 2019 at 12:33:26PM -0500, Paul Thomas wrote:
> > > Yes changing it to TSTAMP_ALL_PTP_FRAMES instead of TSTAMP_ALL_FRAMES
> > > does seem to fix the ssh issue. My worry is that there is still a bug
> > > somewhere in the network stack that this is just masking.
>
> Ok thanks.
> One place to check in the driver will be:
> if (gem_ptp_do_txstamp(queue, skb, desc) == 0) {
> /* skb now belongs to timestamp buffer
> * and will be removed later
> */
> tx_skb->skb = NULL;
> }
> When all TX packets are timestamped, the skb always belongs to the
> timestamp buffer.
>
> >
> > Or the HW isn't sending the frames in the first place.
> >
> > Check that first!
>
> To check this, the statistics registers in MAC will be one way.
> But if there is no TX completion interrupt, then I wouldn't expect
> these statistics to increase either. The used bit status in BD dump
> might be of more use.
>
> I will also try to reproduce (with TX timestamp ALL) and see if any of
> the above gives some clue.
>
> Regards,
> Harini

Hi Harini, any luck looking at this?

I didn't get very far, even in the "broken" state I see plenty of tx_frames:
root@xu5:/opt/linuxptp# ethtool -S eth0
NIC statistics:
     ...
     tx_frames: 39763
     ...

When you said "registers in the MAC" is ethtool -S displaying that?

-Paul