netdev - Re: [PATCH 1/5] net: fec: properly support external PTP PHY for hardware time stamping

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Message-ID: <20200708105506.GB9080@hoboy>
Date:   Wed, 8 Jul 2020 03:55:06 -0700
From:   Richard Cochran <richardcochran@...il.com>
To:     Sergey Organov <sorganov@...il.com>
Cc:     Vladimir Oltean <olteanv@...il.com>, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org, Fugang Duan <fugang.duan@....com>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>, andrew@...n.ch
Subject: Re: [PATCH  1/5] net: fec: properly support external PTP PHY for
 hardware time stamping

On Mon, Jul 06, 2020 at 09:33:30PM +0300, Sergey Organov wrote:
> Vladimir Oltean <olteanv@...il.com> writes:
> 
> > On Mon, Jul 06, 2020 at 06:21:59PM +0300, Sergey Organov wrote:
> > Both are finicky in their own ways. There is no real way for the user to
> > select which PHC they want to use. The assumption is that you'd always
> > want to use the outermost one, and that things in the kernel side always
> > collaborate towards that end.

+1

In addition, for PHY time stamping you must enable the costly
CONFIG_NETWORK_PHY_TIMESTAMPING option at compile time, and so the
user most definitely wants the "outer" function.

> Makes sense, -- thanks for clarification! Indeed, if somebody connected
> that external thingy, chances are high it was made for a purpose.

Yes, exactly.

Thanks,
Richard