netdev - Re: [PATCH net-next] ptp: ocp: Add ptp_ocp_adjtime

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Message-ID: <20220301125111.GB14297@hoboy.vegasvil.org>
Date:   Tue, 1 Mar 2022 04:51:11 -0800
From:   Richard Cochran <richardcochran@...il.com>
To:     Jonathan Lemon <jonathan.lemon@...il.com>
Cc:     netdev@...r.kernel.org, davem@...emloft.net, kuba@...nel.org,
        kernel-team@...com
Subject: Re: [PATCH net-next] ptp: ocp: Add ptp_ocp_adjtime_coarse for large
 adjustments

On Mon, Feb 28, 2022 at 12:39:57PM -0800, Jonathan Lemon wrote:
> In ("ptp: ocp: Have FPGA fold in ns adjustment for adjtime."), the
> ns adjustment was written to the FPGA register, so the clock could
> accurately perform adjustments.
> 
> However, the adjtime() call passes in a s64, while the clock adjustment
> registers use a s32.  When trying to perform adjustments with a large
> value (37 sec), things fail.
> 
> Examine the incoming delta, and if larger than 1 sec, use the original
> (coarse) adjustment method.  If smaller than 1 sec, then allow the
> FPGA to fold in the changes over a 1 second window.
> 
> Fixes: 6d59d4fa1789 ("ptp: ocp: Have FPGA fold in ns adjustment for adjtime.")
> Signed-off-by: Jonathan Lemon <jonathan.lemon@...il.com>

Acked-by: Richard Cochran <richardcochran@...il.com>