netdev - Re: [PATCH RFC V1 net-next 3/4] net: Let the active time stamping layer be selectable.

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Date:   Wed, 6 Apr 2022 14:18:38 +0300
From:   Grygorii Strashko <grygorii.strashko@...com>
To:     Richard Cochran <richardcochran@...il.com>,
        Andrew Lunn <andrew@...n.ch>
CC:     Kurt Kanzenbach <kurt@...utronix.de>,
        Michael Walle <michael@...le.cc>, <davem@...emloft.net>,
        <kuba@...nel.org>, <linux-kernel@...r.kernel.org>,
        <linux@...linux.org.uk>, <mlichvar@...hat.com>,
        <netdev@...r.kernel.org>, <qiangqing.zhang@....com>,
        <vladimir.oltean@....com>
Subject: Re: [PATCH RFC V1 net-next 3/4] net: Let the active time stamping
 layer be selectable.



On 05/04/2022 18:48, Richard Cochran wrote:
> On Tue, Apr 05, 2022 at 03:29:05PM +0200, Andrew Lunn wrote:
> 
>> Maybe. Device tree is supposed to describe the hardware, not how you
>> configure the hardware. Which PTP you using is a configuration choice,
>> so i expect some people will argue it should not be in DT.
> 
> +1
> 
> Pure DT means no configuration choices.
> 
> (but you find many examples that break the rules!)
> 

My point was related to one of issues described by Michael Walle in this thread:
- supporting TS by the PHY may require also additional board support;
- phy_has_hwtstamp() defined statically by PHY drivers without taking into account board design;
- Kconfig option Doesn't really work with generic distro support and not allowed per-port cfg.

So adding smth like "hwtstamp-en" will clear identify that this particular PHY on this particular board
supports time stamping.
(or hwtstamp-full/hwtstamp-rx/hwtstamp-tx).

Of course, it will not help with default or dynamic selection of time stamping layer :(,
but it will be one problem less.

-- 
Best regards,
Grygorii, Ukraine