netdev - Re: [RFC 0/3] ptp: Add esterror support

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Message-ID: <4c2e99b4-b19e-41f5-a048-3bcc8c33a51c@lunn.ch>
Date: Tue, 13 Aug 2024 22:05:31 +0200
From: Andrew Lunn <andrew@...n.ch>
To: Maciek Machnikowski <maciek@...hnikowski.net>
Cc: netdev@...r.kernel.org, richardcochran@...il.com,
	jacob.e.keller@...el.com, vadfed@...a.com, darinzon@...zon.com,
	kuba@...nel.org
Subject: Re: [RFC 0/3] ptp: Add esterror support

On Tue, Aug 13, 2024 at 12:55:59PM +0000, Maciek Machnikowski wrote:
> This patch series implements handling of timex esterror field
> by ptp devices.
> 
> Esterror field can be used to return or set the estimated error
> of the clock. This is useful for devices containing a hardware
> clock that is controlled and synchronized internally (such as
> a time card) or when the synchronization is pushed to the embedded
> CPU of a DPU.

How can you set the estimated error of a clock? Isn't it a properties
of the hardware, and maybe the network link? A 10BaseT/Half duplex
link is going to have a bigger error than a 1000BaseT link because the
bits take longer on the wire etc.

What is the device supposed to do with the set value?

     Andrew