netdev - Re: [net-next 03/15] net/mlx5: Add adjphase function to support hardware-only offset control

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Date:   Tue, 24 Jan 2023 11:15:31 -0800
From:   Richard Cochran <richardcochran@...il.com>
To:     Bar Shapira <bar.shapira.work@...il.com>
Cc:     Rahul Rameshbabu <rrameshbabu@...dia.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Jacob Keller <jacob.e.keller@...el.com>,
        Saeed Mahameed <saeed@...nel.org>,
        "David S. Miller" <davem@...emloft.net>,
        Paolo Abeni <pabeni@...hat.com>,
        Eric Dumazet <edumazet@...gle.com>,
        Saeed Mahameed <saeedm@...dia.com>, netdev@...r.kernel.org,
        Tariq Toukan <tariqt@...dia.com>,
        Gal Pressman <gal@...dia.com>,
        Vincent Cheng <vincent.cheng.xh@...esas.com>
Subject: Re: [net-next 03/15] net/mlx5: Add adjphase function to support
 hardware-only offset control

On Tue, Jan 24, 2023 at 12:33:05PM +0200, Bar Shapira wrote:
> I guess this expectation should be part of the documentation too, right? Are
> there more expectations when calling adjphase?

I'll gladly ack improvements to the documentation. I myself won't
spend time on that, because it will only get ignored, even when it is
super clear.  Like ptp_clock_register(), for example.

> In previous responses on the mailing list it said that adjphase should not
> cause the time to 'jump' - is it also correct?

correct.
 
> It seems that "Feeds the given phase offset into the hardware clock's servo"
> is still missing some information.
> Can you help clarify the expected result after calling adjphase from SW?

If you don't have a servo implemented in hardware, then don't
implement .adjphase in your device driver.

Thanks,
Richard