netdev - Re: [PATCH net-next 1/9] ptp: Clarify ptp_clock_info .adjphase expects an internal servo to be used

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Message-ID: <ZFxOZM9saCVDNIqD@hoboy.vegasvil.org>
Date: Wed, 10 May 2023 19:09:40 -0700
From: Richard Cochran <richardcochran@...il.com>
To: Rahul Rameshbabu <rrameshbabu@...dia.com>
Cc: netdev@...r.kernel.org, Saeed Mahameed <saeed@...nel.org>,
	Gal Pressman <gal@...dia.com>, Tariq Toukan <tariqt@...dia.com>,
	"David S. Miller" <davem@...emloft.net>,
	Jakub Kicinski <kuba@...nel.org>,
	Jacob Keller <jacob.e.keller@...el.com>
Subject: Re: [PATCH net-next 1/9] ptp: Clarify ptp_clock_info .adjphase
 expects an internal servo to be used

On Wed, May 10, 2023 at 01:52:58PM -0700, Rahul Rameshbabu wrote:
> +PTP hardware clock requirements for '.adjphase'
> +-----------------------------------------------
> +
> +   The 'struct ptp_clock_info' interface has a '.adjphase' function.
> +   This function has a set of requirements from the PHC in order to be
> +   implemented.
> +
> +     * The PHC implements a servo algorithm internally that is used to
> +       correct the offset passed in the '.adjphase' call.
> +     * When other PTP adjustment functions are called, the PHC servo
> +       algorithm is disabled,

I disagree with this part:

> and the frequency prior to the '.adjphase'
> +       call is restored internally in the PHC.

That seems like an arbitrary rule that doesn't make much sense.

Thanks,
Richard