netdev - Re: [PATCH net-next v6 2/3] net: phy: broadcom: Add PTP support for some Broadcom PHYs.

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Date:   Wed, 08 Jun 2022 14:29:15 -0700
From:   Jonathan Lemon <jonathan.lemon@...il.com>
To:     Richard Cochran <richardcochran@...il.com>
Cc:     netdev@...r.kernel.org, kernel-team@...com,
        Andrew Lunn <andrew@...n.ch>,
        Florian Fainelli <f.fainelli@...il.com>,
        Lasse Johnsen <l@...johnsen.me>,
        Heiner Kallweit <hkallweit1@...il.com>,
        Russell King <linux@...linux.org.uk>,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        Broadcom internal kernel review list 
        <bcm-kernel-feedback-list@...adcom.com>
Subject: Re: [PATCH net-next v6 2/3] net: phy: broadcom: Add PTP support for some Broadcom PHYs.

On 8 Jun 2022, at 13:55, Richard Cochran wrote:

> On Wed, Jun 08, 2022 at 01:44:50PM -0700, Jonathan Lemon wrote:
>> This adds PTP support for BCM54210E Broadcom PHYs, in particular,
>> the BCM54213PE, as used in the Rasperry PI CM4.  It has only been
>> tested on that hardware.
>
> ...
>
>> +static const struct ptp_clock_info bcm_ptp_clock_info = {
>> +	.owner		= THIS_MODULE,
>> +	.name		= KBUILD_MODNAME,
>> +	.max_adj	= 100000000,
>
> Does this really work?  See below.
>
>> +	.gettimex64	= bcm_ptp_gettimex,
>> +	.settime64	= bcm_ptp_settime,
>> +	.adjtime	= bcm_ptp_adjtime,
>> +	.adjfine	= bcm_ptp_adjfine,
>> +	.do_aux_work	= bcm_ptp_do_aux_work,
>> +};
>
> On another phy from the same (?) family (541xx), I found that the
> synch becomes unstable when slewing more than:
>
> 	port->caps.max_adj	= 62500,

The 100000000 value I probably copied from elsewhere.

For testing, I’ve been running ts2phc and ptp4l, and haven’t noticed any
problems - but may have just been lucky.

Do you have a stress test to verify one way or the other?
—
Jonathan