linux-kernel - Re: [PATCH net] net: dsa: sja1105: fix PTP timestamping with large tc-taprio cycles

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Message-ID: <20200615125843.GC16362@localhost>
Date:   Mon, 15 Jun 2020 05:58:43 -0700
From:   Richard Cochran <richardcochran@...il.com>
To:     Vladimir Oltean <olteanv@...il.com>
Cc:     f.fainelli@...il.com, vivien.didelot@...il.com, andrew@...n.ch,
        davem@...emloft.net, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org, vinicius.gomes@...el.com
Subject: Re: [PATCH net] net: dsa: sja1105: fix PTP timestamping with large
 tc-taprio cycles

On Sun, Jun 14, 2020 at 11:54:09PM +0300, Vladimir Oltean wrote:
> So fix this case of premature optimization by simply reordering the
> sja1105_ptpegr_ts_poll and the sja1105_ptpclkval_read function calls. It
> turns out that in practice, the 135 ms hard deadline for PTP timestamp
> wraparound is not so hard, since even the most bandwidth-intensive PTP
> profiles, such as 802.1AS-2011, have a sync frame interval of 125 ms.
> So if we couldn't deliver a timestamp in 135 ms (which we can), we're
> toast and have much bigger problems anyway.
> 
> Fixes: 47ed985e97f5 ("net: dsa: sja1105: Add logic for TX timestamping")
> Signed-off-by: Vladimir Oltean <vladimir.oltean@....com>
> ---

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