netdev - Re: [PATCH net-next v5 2/2] net: phy: broadcom: Add PTP support for some Broadcom PHYs.

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Message-Id: <57926B53-BB8B-4A9B-9340-0DFFDA4452BA@flugsvamp.com>
Date:   Mon, 30 May 2022 18:15:44 -0700
From:   Flugsvamp <jlemon@...gsvamp.com>
To:     Richard Cochran <richardcochran@...il.com>
Cc:     Jonathan Lemon <jonathan.lemon@...il.com>, netdev@...r.kernel.org,
        f.fainelli@...il.com, andrew@...n.ch, hkallweit1@...il.com,
        linux@...linux.org.uk, bcm-kernel-feedback-list@...adcom.com,
        kernel-team@...com, davem@...emloft.net, kuba@...nel.org,
        pabeni@...hat.com, edumazet@...gle.com
Subject: Re: [PATCH net-next v5 2/2] net: phy: broadcom: Add PTP support for some Broadcom PHYs.



> On May 30, 2022, at 4:04 PM, Richard Cochran <richardcochran@...il.com> wrote:
> 
> On Mon, May 30, 2022 at 10:07:44AM -0700, Jonathan Lemon wrote:
>>> On Sat, May 28, 2022 at 05:34:47PM -0700, Richard Cochran wrote:
>>>> On Wed, May 18, 2022 at 03:39:35PM -0700, Jonathan Lemon wrote:
>>> 
>>>> +static int bcm_ptp_adjtime_locked(struct bcm_ptp_private *priv,
>>>> +                  s64 delta_ns)
>>>> +{
>>>> +    struct timespec64 ts;
>>>> +    int err;
>>>> +
>>>> +    err = bcm_ptp_gettime_locked(priv, &ts, NULL);
>>>> +    if (!err) {
>>>> +        set_normalized_timespec64(&ts, ts.tv_sec,
>>>> +                      ts.tv_nsec + delta_ns);
>>> 
>>> This also takes a LONG time when delta is large...
>> 
>> Didn't we just go through this?  What constitutes a "large" offset here?
>> The current version seems acceptable to me:
> 
> When the PHY boots, it starts from time zero.
> 
> Then as a client it needs to adjust to today, something like:
> 
> 1653951762.413809006 or Mon May 30 16:02:42 2022
> 
> (that means adding 1,653,951,762,413,809,006 nanoseconds)
> 
> Try that and see how long it takes to apply the adjustment.

That’s certainly a big adjustment. I was expecting something along the lines of a settime() call, followed up by adjtime().

Will fix. Seems like there should be a better call sequence for this, though. 

Sent from my iPhone