netdev - Re: [Patch net-next v2 06/13] net: ptp: add helper for one-step P2P clocks

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Date:   Tue, 6 Dec 2022 08:38:07 -0800
From:   Richard Cochran <richardcochran@...il.com>
To:     Arun Ramadoss <arun.ramadoss@...rochip.com>
Cc:     linux-kernel@...r.kernel.org, netdev@...r.kernel.org,
        woojung.huh@...rochip.com, UNGLinuxDriver@...rochip.com,
        andrew@...n.ch, vivien.didelot@...il.com, f.fainelli@...il.com,
        olteanv@...il.com, davem@...emloft.net, edumazet@...gle.com,
        kuba@...nel.org, pabeni@...hat.com, linux@...linux.org.uk,
        Tristram.Ha@...rochip.com, ceggers@...i.de
Subject: Re: [Patch net-next v2 06/13] net: ptp: add helper for one-step P2P
 clocks

On Tue, Dec 06, 2022 at 02:44:21PM +0530, Arun Ramadoss wrote:
> From: Christian Eggers <ceggers@...i.de>
> 
> For P2P delay measurement, the ingress time stamp of the PDelay_Req is
> required for the correction field of the PDelay_Resp. The application
> echoes back the correction field of the PDelay_Req when sending the
> PDelay_Resp.
> 
> Some hardware (like the ZHAW InES PTP time stamping IP core) subtracts
> the ingress timestamp autonomously from the correction field, so that
> the hardware only needs to add the egress timestamp on tx. Other
> hardware (like the Microchip KSZ9563) reports the ingress time stamp via
> an interrupt and requires that the software provides this time stamp via
> tail-tag on tx.
> 
> In order to avoid introducing a further application interface for this,
> the driver can simply emulate the behavior of the InES device and
> subtract the ingress time stamp in software from the correction field.
> 
> On egress, the correction field can either be kept as it is (and the
> time stamp field in the tail-tag is set to zero) or move the value from
> the correction field back to the tail-tag.
> 
> Changing the correction field requires updating the UDP checksum (if UDP
> is used as transport).
> 
> Reported-by: kernel test robot <lkp@...el.com>

How can a test robot report new code additions?

Thanks,
Richard